95ZJ_8D.PDF

553 views
465 views

Published on

Published in: Automotive
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
553
On SlideShare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
13
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

95ZJ_8D.PDF

  1. 1. ZJ IGNITION SYSTEMS 8D - 1 IGNITION SYSTEMS CONTENTS page pageCOMPONENT IDENTIFICATION/SYSTEM DIAGNOSTICS/SERVICE PROCEDURES . . . . . . . 6 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 IGNITION SWITCH . . . . . . . . . . . . . . . . . . . . . . . 29COMPONENT REMOVAL/INSTALLATION . . . . . . 17 SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . 32 COMPONENT IDENTIFICATION/SYSTEM OPERATION INDEX page pageAutomatic Shutdown (ASD) Relay . . . . . . . . . . . . . . 1 Ignition Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Camshaft Position Sensor . . . . . . . . . . . . . . . . . . . . 2 Intake Manifold Air Temperature Sensor . . . . . . . . . . 5Crankshaft Position Sensor . . . . . . . . . . . . . . . . . . . 2 Manifold Absolute Pressure (MAP) Sensor . . . . . . . . 5Distributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Oxygen (O2S) Sensor . . . . . . . . . . . . . . . . . . . . . . . 5Engine Coolant Temperature Sensor . . . . . . . . . . . . 4 Powertrain Control Module (PCM) . . . . . . . . . . . . . . 5General Information . . . . . . . . . . . . . . . . . . . . . . . . 1 Throttle Position Sensor . . . . . . . . . . . . . . . . . . . . . 5GENERAL INFORMATION IGNITION SYSTEMS Throughout this group, references are made to par- The distributors used on 4.0L 6-cylinder and 5.2Lticular vehicle models by alphabetical designation or V-8 engines are basically the same for the 1995by the particular vehicle nameplate. A chart showing model year. Similarities and differences between thea breakdown of alphabetical designations is included two distributors will be discussed.in the Introduction group at the beginning of this A multi-port, fuel injected engine is used on allmanual. models. The ignition system is controlled by the pow- This section of the group, Component Identifica- ertrain control module (PCM) on all engines. Thetion/System Operation, will discuss ignition system PCM was formerly referred to as the SBEC or engineoperation and will identify ignition system compo- controller.nents. The ignition system consists of: For diagnostic procedures and adjustments, refer to • Spark plugsthe Diagnostics/Service Procedures section of this • Ignition coilgroup. • Secondary ignition cables For removal and installation of ignition system • Distributor (contains rotor and camshaft positioncomponents, refer to the Component Removal/Instal- sensor)lation section of this group. • Powertrain control module (PCM) For other useful information, refer to On-Board Di- • Crankshaft position sensoragnostics in the General Diagnosis sections of Group14, Fuel System in this manual. AUTOMATIC SHUTDOWN (ASD) RELAY For operation of the DRB scan tool, refer to the ap- The automatic shutdown (ASD) relay is located inpropriate Powertrain Diagnostic Procedures service the power distribution center (PDC) near the batterymanual. (Fig. 1). As one of its functions, it will supply battery An Ignition specifications section is included at the voltage to the ignition coil. The ground circuit for theend of this group. A general Maintenance Schedule ASD relay is controlled by the powertrain control(mileage intervals) for ignition related items can be module (PCM). The PCM regulates ASD relay opera-found in Group 0, Lubrication and Maintenance. This tion by switching the ground circuit on-and-off.schedule can also be found in the Owners Manual.
  2. 2. 8D - 2 IGNITION SYSTEMS ZJ When the leading edge of the pulse ring (shutter) enters the sync signal generator, the following occurs: The interruption of magnetic field causes the voltage to switch high resulting in a sync signal of approxi- mately 5 volts. When the trailing edge of the pulse ring (shutter) leaves the sync signal generator, the following occurs: The change of the magnetic field causes the sync sig- nal voltage to switch low to 0 volts. For component testing, refer to the Diagnostics/Ser- vice Procedures section of this group. For removal and installation of this component, re- fer to the Component Removal/Installation section of this group. CRANKSHAFT POSITION SENSOR 4.0L 6-CYLINDER ENGINES WITH MANUAL TRANSMISSION: The crankshaft position sensor is mounted to the transmission bellhousing with two bolts at the left/ Fig. 1 Power Distribution Center rear side of the engine block (Fig. 3).CAMSHAFT POSITION SENSOR The camshaft position sensor is located in the dis-tributor (Fig. 2) on all engines. This sensor is similaron both the 4.0L and 5.2L engines for the 1995 modelyear. Fig. 3 Crankshaft Position Sensor—4.0L Engine With Manual Transmission 4.0L 6-CYLINDER ENGINES WITH AUTOMATIC TRANSMISSION The crankshaft position sensor is mounted to the Fig. 2 Camshaft Position Sensor—Typical transmission bellhousing with one bolt at the left/ rear side of the engine block (Fig. 4). The camshaft position sensor contains a hall effectdevice called a sync signal generator to generate a 5.2L V-8 ENGINEfuel sync signal. This sync signal generator (Fig. 2) On 5.2L engines, the sensor is bolted to the top ofdetects a rotating pulse ring (shutter) on the distrib- cylinder block near the rear of the right cylinderutor shaft. The pulse ring rotates 180 degrees head (Fig. 5).through the sync signal generator. Its signal is used Engine speed and crankshaft position are providedin conjunction with the crankshaft position sensor to through the crankshaft position sensor. The sensordifferentiate between fuel injection and spark events. generates pulses that are the input sent to the pow-It is also used to synchronize the fuel injectors with ertrain control module (PCM). The PCM interpretstheir respective cylinders. the sensor input to determine the crankshaft posi-
  3. 3. ZJ IGNITION SYSTEMS 8D - 3 SENSOR OPERATION—4.0L ENGINE The flywheel/drive plate has groups of four notches at its outer edge. On 4.0L engines there are three sets of notches (Fig. 6). The notches cause a pulse to be generated when they pass under the sensor. The pulses are the input to the PCM. For each engine revolution there are there are 3 groups of four pulses generated on 4.0L 6-cylinder engines. The trailing edge of the fourth notch, which causes the pulse, is four degrees before top dead center (TDC) of the corresponding piston. The engine will not operate if the PCM does not re- ceive a crankshaft position sensor input. For component testing, refer to the Diagnostics/Ser- vice Procedures section of this group. For removal and installation of this sensor, refer to the Component Removal/Installation section of this group. Fig. 4 Crankshaft Position Sensor—4.0L Engine With Automatic Transmission Fig. 6 Sensor Operation—4.0L Engine—Typical SENSOR OPERATION—5.2L V-8 ENGINE On 5.2L engines, the flywheel/drive plate has 8 sin- gle notches, spaced every 45 degrees, at its outer edge (Fig. 7). Fig. 5 Crankshaft Position Sensor—5.2L Engine— The notches cause a pulse to be generated when Typical they pass under the sensor. The pulses are the inputtion. The PCM then uses this position, along with to the PCM. For each engine revolution, there are 8other inputs, to determine injector sequence and ig- pulses generated on 5.2L V-8 engines.nition timing. The engine will not operate if the PCM does not re- The sensor is a hall effect device combined with an ceive a crankshaft position sensor input.internal magnet. It is also sensitive to steel within a For component testing, refer to the Diagnostics/Ser-certain distance from it. vice Procedures section of this group. For removal and installation of this component, re- fer to the Component Removal/Installation section of this group.
  4. 4. 8D - 4 IGNITION SYSTEMS ZJ For removal and installation of this component, re- fer to the Component Removal/Installation section of this group. IGNITION COIL Battery voltage is supplied to the ignition coil pos- itive terminal from the ASD relay. The powertrain control module (PCM) opens and closes the ignition coil ground circuit for ignition coil operation. Base ignition timing is not adjustable. By con- trolling the coil ground circuit, the PCM is able to set the base timing and adjust the ignition timing ad- vance. This is done to meet changing engine operat- ing conditions. The ignition coil is not oil filled. The windings are embedded in an epoxy compound. This provides heat and vibration resistance that allows the ignition coil to be mounted on the engine. On 4.0L 6-cylinder engines, the ignition coil is mounted to a bracket on the side of the engine (Fig. 8). Fig. 7 Sensor Operation—5.2L V-8 Engine On 5.2L V-8 engines, the ignition coil is mounted toDISTRIBUTORS a bracket at the front of the right cylinder head (Fig. All engines are equipped with a camshaft driven 9). This bracket is also used to mount the automaticmechanical distributor, containing a shaft driven dis- belt tensioner.tributor rotor. All distributors are equipped with aninternal camshaft position (fuel sync) sensor (Fig. 2).This sensor provides fuel injection synchronizationand cylinder identification. The distributors on 4.0L or 5.2L engines do nothave built in centrifugal or vacuum assisted advance.Base ignition timing and all timing advance is con-trolled by the powertrain control module (PCM). Be-cause ignition timing is controlled by the PCM, baseignition timing is not adjustable on any of theseengines. On the 4.0L 6-cylinder engine, the distributor islocked in place by a notch on the distributor housing.The distributor holddown clamp bolt passes throughthis notch when installed. Because the distributor po-sition is locked when installed, its rotational positioncan not be changed. Do not attempt to modify the Fig. 8 Ignition Coil—4.0L Engine—Typicaldistributor housing to get distributor rotation. For component testing, refer to the Diagnostics/Ser-Distributor position will have no effect on igni- vice Procedures section of this group.tion timing. For removal and installation of this component, re- On the 5.2L V-8 engine, the distributor is held to fer to the Component Removal/Installation section ofthe engine in the conventional method using a hold-down clamp and bolt. Although the distributor on this group.the 5.2L engine can be rotated, it will have noeffect on ignition timing. ENGINE COOLANT TEMPERATURE SENSOR All distributors contain an internal oil seal that For an operational description, diagnosis and re-prevents oil from entering the distributor housing. moval/installation procedures, refer to Group 14,The seal is not serviceable. Fuel System. For component testing, refer to the Diagnostics/Ser-vice Procedures section of this group.
  5. 5. ZJ IGNITION SYSTEMS 8D - 5 Fig. 9 Ignition Coil—5.2L Engine—TypicalINTAKE MANIFOLD AIR TEMPERATURE SENSOR For an operational description, diagnosis and re-moval/installation procedures, refer to the Diagnosissections of Group 14, Fuel System. Fig. 10 PCM Location—TypicalMANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR For removal and installation of this component, re- For an operational description, diagnosis and re-moval/installation procedures, refer to Group 14, fer to the Component Removal/Installation section ofFuel System. this group. For diagnostics, refer to the appropriate PowertrainPOWERTRAIN CONTROL MODULE (PCM) Diagnostic Procedures service manual for operation The PCM (formerly called the SBEC or engine con- of the DRB scan tool.troller) is located in the right/rear side of the enginecompartment (Fig. 10). THROTTLE POSITION SENSOR The ignition system is controlled by the PCM. For an operational description, diagnosis and re- Base ignition timing by rotation of distributor moval/installation procedures, refer to Group 14,is not adjustable. The PCM opens and closes the ig- Fuel System.nition coil ground circuit to operate the ignition coil.This is done to adjust ignition timing, both initial OXYGEN (O2S) SENSOR(base) and advance, for changing engine operating For an operational description, diagnosis and re-conditions. moval/installation procedures, refer to Group 14, The amount of electronic spark advance provided Fuel System.by the PCM is determined by five input factors: En-gine coolant temperature, engine rpm, intake mani-fold air temperature, manifold absolute pressure andthrottle position.
  6. 6. 8D - 6 IGNITION SYSTEMS ZJ DIAGNOSTICS/SERVICE PROCEDURES INDEX page pageAutomatic Shutdown (ASD) Relay . . . . . . . . . . . . . . 6 Ignition Timing . . . . . . . . . . . . . . . . . . . . . . . ... . 12Camshaft Position Sensor Test . . . . . . . . . . . . . . . . 6 Intake Manifold Air Temperature Sensor Test . ... . 12Crankshaft Position Sensor Test . . . . . . . . . . . . . . . 7 Manifold Absolute Pressure (MAP) Sensor Test .. . 12Distributor Cap . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 On-Board Diagnostics . . . . . . . . . . . . . . . . . . ... . 16Distributor Rotor . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Oxygen Sensor Tests . . . . . . . . . . . . . . . . . . ... . 16DRB Scan Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Powertrain Control Module (PCM) . . . . . . . . . ... . 12Engine Coolant Temperature Sensor Test . . . . . . . 10 Spark Plug Secondary Cables . . . . . . . . . . . . ... . 14General Information . . . . . . . . . . . . . . . . . . . . . . . . 6 Spark Plugs . . . . . . . . . . . . . . . . . . . . . . . . . ... . 12Ignition Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Throttle Position Sensor Test . . . . . . . . . . . . . ... . 16Ignition Secondary Circuit Diagnosis . . . . . . . . . . . 10GENERAL INFORMATION This section of the group, Diagnostics/Service Pro-cedures, will discuss basic ignition system diagnosticsand service adjustments. For system operation and component identification,refer to the Component Identification/System Opera-tion section of this group. For removal or installation of ignition system com-ponents, refer to the Component Removal/Installa-tion section of this group. For other useful information, refer to On-Board Di-agnostics in the General Diagnosis sections of Group14, Fuel System in this manual. For operation of the DRB Scan Tool, refer to theappropriate Powertrain Diagnostic Procedures ser-vice manual. Fig. 1 Camshaft Position Sensor—TypicalAUTOMATIC SHUTDOWN (ASD) RELAY To perform a complete test of the ASD relay and its (1) Connect the positive (+) voltmeter lead into thecircuitry, refer to the DRB scan tool and appropriate sensor output wire. This is at done the distributorPowertrain Diagnostics Procedures manual. To test wire harness connector. For wire identification, referthe sensor only, refer to Relays—Operation/Testing in to Group 8W, Wiring Diagrams.the Group 14, Fuel System section of this service (2) Connect the negative (-) voltmeter lead into themanual. ground wire. For wire identification, refer to Group 8W, Wiring Diagrams.CAMSHAFT POSITION SENSOR TEST (3) Set the voltmeter to the 15 Volt DC scale. The camshaft position sensor is located in the dis- 4.0L Engines: Remove distributor cap. Rotatetributor on all engines (Fig. 1). (crank) engine with starter until rotor is pointed in To perform a complete test of this sensor and its the 10 o’clock position. The movable pulse ring (Fig.circuitry, refer to the DRB scan tool. Also refer to the 1) will now be within the magnetic pickup on theappropriate Powertrain Diagnostics Procedures man- camshaft position sensor.ual. To test the sensor only, refer to the following: 5.2L Engines: Remove coil high-tension cable and all spark plug cables at distributor cap. Note and4.0L OR 5.2L ENGINE mark position of cables before removal (Fig. 2). Re- For this test, an analog voltmeter is needed. move distributor cap from distributor (two screws).Do not remove the distributor connector from the dis- Rotate (crank) the engine until the rotor is pointedtributor. Using small paper clips, insert them into towards the rear of vehicle. The movable pulse ringthe backside of the distributor wire harness connec- (Fig. 1) will now be within the magnetic pickup ontor to make contact with the terminals. Be sure that the camshaft position sensor.the connector is not damaged when inserting the pa- (4) Turn ignition key to ON position. Voltmeterper clips. Attach voltmeter leads to these paper clips. should read approximately 5.0 volts.
  7. 7. ZJ IGNITION SYSTEMS 8D - 7 CRANKSHAFT POSITION SENSOR TEST To perform a complete test of this sensor and its circuitry, refer to the DRB scan tool. Also refer to the appropriate Powertrain Diagnostics Procedures man- ual. To test the sensor only, refer to the following: On the 4.0L engine, the sensor is located on the transmission bellhousing at the left/rear side of the engine block (Figs. 3 or 4). Fig. 2 Engine Firing Order—5.2L Engine (5) If voltage is not present, check the voltmeterleads for a good connection. (6) If voltage is still not present, check for voltageat the supply wire. For wire identification, refer toGroup 8W, Wiring Diagrams. (7) If voltage is not present at supply wire, checkfor voltage at pin-7 of powertrain control module(PCM) 60-way connector. Leave the PCM connectorconnected for this test. Fig. 3 Crankshaft Position Sensor—4.0L Engine With Manual Transmission (8) If voltage is still not present, perform vehicletest using the DRB scan tool. (9) If voltage is present at pin-7, but not at thesupply wire: (a) Check continuity between the supply wire. This is checked between the distributor connector and pin-7 at the PCM. If continuity is not present, repair the harness as necessary. (b) Check for continuity between the camshaft position sensor output wire and pin-44 at the PCM. If continuity is not present, repair the harness as necessary. (c) Check for continuity between the ground cir- cuit wire at the distributor connector and ground. If continuity is not present, repair the harness as necessary. (10) While observing the voltmeter, crank the en-gine with ignition switch. The voltmeter needleshould fluctuate between 0 and 5 volts while the en-gine is cranking. This verifies that the camshaft po-sition sensor is operating properly and a sync pulsesignal is being generated. If a sync pulse signal is not present, replacement of Fig. 4 Crankshaft Position Sensor—4.0L Enginethe camshaft position sensor is necessary. With Automatic Transmission For removal or installation of ignition system com-ponents, refer to the Component Removal/Installa-tion section of this group. For system operation and component identification,refer to the Component Identification/System Opera-tion section of this group.
  8. 8. 8D - 8 IGNITION SYSTEMS ZJ On the 5.2L engine, the sensor is located on the top DISTRIBUTOR CAPof cylinder block near the rear of right cylinder head(Fig. 5). INSPECTION (1) Near the rear of intake manifold, disconnect Remove the distributor cap and wipe it clean withsensor pigtail harness connector from main wiring a dry lint free cloth. Visually inspect the cap forharness. cracks, carbon paths, broken towers, or damaged ro- tor button (Figs. 7 and 8). Also check for white depos- its on the inside (caused by condensation entering the cap through cracks). Replace any cap that dis- plays charred or eroded terminals. The inside flat surface of a terminal end (faces toward rotor) will in- dicate some evidence of erosion from normal opera- tion. Examine the terminal ends for evidence of mechanical interference with the rotor tip. Fig. 5 Crankshaft Position Sensor—5.2L Engine— Typical (2) Place an ohmmeter across terminals B and C Fig. 7 Cap Inspection—External—Typical(Fig. 6). Ohmmeter should be set to 1K-to-10K scalefor this test. The meter reading should be open (noresistance). Replace sensor if a low resistance is indi-cated. Fig. 8 Cap Inspection—Internal—Typical If replacement of the distributor cap is necessary, transfer spark plug cables from the original cap to Fig. 6 Crankshaft Position Sensor Connector the new cap. This should be done one cable at a time. Each cable is installed onto the tower of the new cap that corresponds to its tower position on the original cap. Fully seat the cables onto the towers. If neces- sary, refer to the Engine Firing Order diagrams (Figs. 9 or 10).
  9. 9. ZJ IGNITION SYSTEMS 8D - 9Fig. 9 Engine Firing Order—4.0L 6-Cylinder Engine Fig. 11 Rotor Inspection—Typical the appropriate Powertrain Diagnostics Procedures manual. To test the coil only, refer to the following: The ignition coil (Figs. 12 or 13) is designed to op- erate without an external ballast resistor. Fig. 10 Engine Firing Order—5.2L V-8 EngineDISTRIBUTOR ROTOR Visually inspect the rotor (Fig. 11) for cracks, evi-dence of corrosion, or the effects of arcing on themetal tip. Also check for evidence of mechanical in-terference with the cap. Some charring is normal onthe end of the metal tip. The silicone-dielectric-var-nish-compound applied to the rotor tip for radio in-terference noise suppression, will appear charred.This is normal. Do not remove the charred com-pound. Test the spring for insufficient tension. Re- Fig. 12 Ignition Coil—4.0L Engine—Typicalplace a rotor that displays any of these adverse Inspect the ignition coil for arcing. Test the coil ac-conditions. cording to coil tester manufacturer’s instructions. Test the coil primary and secondary resistance. Re-DRB SCAN TOOL place any coil that does not meet specifications. Refer For operation of the DRB scan tool, refer to the ap- to the Ignition Coil Resistance chart.propriate Powertrain Diagnostic Procedures service If the ignition coil is being replaced, the secondarymanual. spark plug cable must also be checked. Replace cable if it has been burned or damaged.IGNITION COIL Arcing at the tower will carbonize the cable nipple, To perform a complete test of the ignition coil and which if it is connected to a new ignition coil, willits circuitry, refer to the DRB scan tool. Also refer to cause the coil to fail.
  10. 10. 8D - 10 IGNITION SYSTEMS ZJ Fig. 13 Ignition Coil—5.2L Engine Fig. 14 Cable Removal If the secondary coil cable shows any signs of dam-age, it should be replaced with a new cable and newterminal. Carbon tracking on the old cable can causearcing and the failure of a new ignition coil.ENGINE COOLANT TEMPERATURE SENSOR TEST For an operational description, diagnosis and re-moval/installation procedures, refer to Group 14,Fuel System.IGNITION SECONDARY CIRCUIT DIAGNOSISCHECKING FOR SPARKCAUTION: When disconnecting a high voltage cablefrom a spark plug or from the distributor cap, twist Fig. 15 Checking for Spark—Typicalthe rubber boot slightly (1/2 turn) to break it loose(Fig. 14). Grasp the boot (not the cable) and pull it THE PULLEYS, BELTS OR THE FAN. DO NOT WEARoff with a steady, even force. LOOSE FITTING CLOTHING. (1) Disconnect the ignition coil secondary cable (2) Rotate (crank) the engine with the starter mo-from center tower of the distributor cap. Hold the ca- tor and observe the cable terminal for a steady arc. Ifble terminal approximately 12 mm (1/2 in.) from a steady arcing does not occur, inspect the secondarygood engine ground (Fig. 15). coil cable. Refer to Spark Plug Cables in this group. Also inspect the distributor cap and rotor for cracksWARNING: BE VERY CAREFUL WHEN THE ENGINEIS CRANKING. DO NOT PUT YOUR HANDS NEAR IGNITION COIL RESISTANCE
  11. 11. ZJ IGNITION SYSTEMS 8D - 11or burn marks. Repair as necessary. If steady arcingoccurs, connect ignition coil cable to the distributorcap. (3) Remove a cable from one spark plug. (4) Using insulated pliers, hold the cable terminalapproximately 12 mm (1/2 in.) from the engine cylin-der head or block while rotating the engine with thestarter motor. Observe the spark plug cable terminalfor an arc. If steady arcing occurs, it can be expectedthat the ignition secondary system is operating cor-rectly. (note that if the ignition coil cable is re-moved for this test, instead of a spark plugcable, the spark intensity will be much higher.)If steady arcing occurs at the spark plug cables, butthe engine will not start, connect the DRB scan tool.Refer to the Powertrain Diagnostic Procedures ser-vice manual. Fig. 17 Coil Harness Connector—5.2L Engine— TypicalFAILURE TO START TEST To prevent unnecessary diagnostic time and wrong • If the voltage remains near zero during the entiretest results, the previous Checking For Spark test period of cranking, refer to On-Board Diagnostics inshould be performed prior to this test. Group 14, Fuel Systems. Check the powertrain con- trol module and auto shutdown relay.WARNING: SET PARKING BRAKE OR BLOCK THE • If voltage is at or near battery voltage and dropsDRIVE WHEELS BEFORE PROCEEDING WITH THIS to zero after 1-2 seconds of cranking, check the cam-TEST. shaft position sensor-to-powertrain control module circuit. Refer to On-Board Diagnostics in group 14, (1) Unplug the ignition coil harness connector at Fuel Systems.the coil (Figs. 16 or 17). • If voltage remains at or near battery voltage dur- ing the entire 5 seconds, turn the key off. Remove the 60-way connector (Fig. 18) from the powertrain control module (PCM). Check 60-way connector for any spread terminals. Fig. 18 PCM 60-Way Connector (5) Remove test lead from the coil positive termi- Fig. 16 Coil Harness Connector—4.0L Engine— nal. Connect an 18 gauge jumper wire between the Typical battery positive terminal and coil positive terminal. (2) Connect a set of small jumper wires (18 gauge (6) Make the special jumper shown in figure 19.or smaller) between the disconnected harness termi- Using the jumper, momentarily ground terminal-19nals and the ignition coil terminals. To determine po- of the 60-way connector. A spark should be generatedlarity at connector and coil, refer to the Wiring at the coil cable when the ground is removed.Diagrams section. (7) If spark is generated, replace the powertrain (3) Determine that sufficient battery voltage (12.4 control module (PCM).volts) is present for the starting and ignition sys- (8) If spark is not seen, use the special jumper totems. ground the coil negative terminal directly. (4) Crank the engine for 5 seconds while monitor- (9) If spark is produced, repair wiring harness foring the voltage at the coil positive terminal: an open condition.
  12. 12. 8D - 12 IGNITION SYSTEMS ZJ Fig. 19 Special Jumper Ground-to-Coil Negative Terminal (10) If spark is not produced, replace the ignitioncoil.IGNITION TIMING Base (initial) ignition timing is NOT adjust-able on any of the 4.0L 6-cylinder or 5.2L V-8 en-gines. Do not attempt to adjust ignition timingby rotating the distributor. All ignition timing functions are controlled by thepowertrain control module (PCM). Refer to On-Board Fig. 20 PCM Location—TypicalDiagnostics in the Multi-Port Fuel Injection—Gen-eral Diagnosis section of Group 14, Fuel Systems for are pressed into the cylinder head to surround eachmore information. Also refer to the appropriate Pow- spark plug cable boot and spark plug (Fig. 21). Theseertrain Diagnostics Procedures service manual for op- shields protect the spark plug boots from damageeration of the DRB Scan Tool. (due to intense engine heat generated by the exhaust manifolds) and should not be removed. After theINTAKE MANIFOLD AIR TEMPERATURE SENSOR spark plug cable has been installed, the lip of the ca-TEST ble boot should have a small air gap to the top of the For an operational description, diagnosis and re- heat shield (Fig. 21).moval/installation procedures, refer to the Diagnosissections of Group 14, Fuel System.MANIFOLD ABSOLUTE PRESSURE (MAP) SENSORTEST For an operational description, diagnosis and re-moval/installation procedures, refer to Group 14,Fuel System.POWERTRAIN CONTROL MODULE (PCM) The PCM (formerly called the SBEC or engine con-troller) is located in the right/rear side of the enginecompartment (Fig. 20). The ignition system is controlled by the PCM. For diagnostics, refer to the appropriate PowertrainDiagnostic Procedures service manual for operationof the DRB scan tool. Fig. 21 Heat Shields—5.2L V-8 Engine For removal and installation of this component, re- Faulty carbon and/or gas fouled plugs generallyfer to the Component Removal/Installation section of cause hard starting, but they will clean up at higherthis group. engine speeds. Faulty plugs can be identified in aSPARK PLUGS number of ways: poor fuel economy, power loss, de- For spark plug removal, cleaning, gap adjustment crease in engine speed, hard starting and, in general,and installation, refer to the Component Removal/In- poor engine performance.stallation section of this group. Remove the spark plugs and examine them for 5.2L V-8 Engine Only: Spark plug heat shields burned electrodes and fouled, cracked or broken por-
  13. 13. ZJ IGNITION SYSTEMS 8D - 13celain insulators. Keep plugs arranged in the order of the entire set of spark plugs may be caused by ain which they were removed from the engine. An iso- clogged air cleaner element or repeated short operat-lated plug displaying an abnormal condition indicates ing times (short trips).that a problem exists in the corresponding cylinder.Replace spark plugs at the intervals recommended in WET FOULING OR GAS FOULINGthe maintenance chart in Group 0, Lubrication and A spark plug coated with excessive wet fuel or oil isMaintenance. wet fouled. In older engines, worn piston rings, leak- Spark plugs that have low mileage may be cleaned ing valve guide seals or excessive cylinder wear canand reused if not otherwise defective. Refer to the cause wet fouling. In new or recently overhauled en-following Spark Plug Condition section of this group. gines, wet fouling may occur before break-in (normal oil control) is achieved. This condition can usually beCONDITION resolved by cleaning and reinstalling the fouled plugs.NORMAL OPERATING OIL OR ASH ENCRUSTED The few deposits present on the spark plug willprobably be light tan or slightly gray in color. This is If one or more spark plugs are oil or oil ash en-evident with most grades of commercial gasoline crusted (Fig. 23), evaluate engine condition for the cause of oil entry into that particular combustion(Fig. 22). There will not be evidence of electrode chamber.burning. Gap growth will not average more than ap-proximately 0.025 mm (.001 in) per 1600 km (1000miles) of operation. Spark plugs that have normalwear can usually be cleaned, have the electrodesfiled, have the gap set and then be installed.Fig. 22 Normal Operation and Cold (Carbon) Fouling Some fuel refiners in several areas of the United Fig. 23 Oil or Ash EncrustedStates have introduced a manganese additive (MMT) ELECTRODE GAP BRIDGINGfor unleaded fuel. During combustion, fuel with MMT Electrode gap bridging may be traced to loose de-causes the entire tip of the spark plug to be coated posits in the combustion chamber. These deposits ac-with a rust colored deposit. This rust color can be cumulate on the spark plugs during continuous stop-misdiagnosed as being caused by coolant in the com- and-go driving. When the engine is suddenlybustion chamber. Spark plug performance is not af- subjected to a high torque load, deposits partially liq-fected by MMT deposits. uefy and bridge the gap between electrodes (Fig. 24). This short circuits the electrodes. Spark plugs withCOLD FOULING/CARBON FOULING electrode gap bridging can be cleaned using standard Cold fouling is sometimes referred to as carbon procedures.fouling. The deposits that cause cold fouling are ba-sically carbon (Fig. 22). A dry, black deposit on one or SCAVENGER DEPOSITStwo plugs in a set may be caused by sticking valves Fuel scavenger deposits may be either white or yel-or defective spark plug cables. Cold (carbon) fouling low (Fig. 25). They may appear to be harmful, but this is a normal condition caused by chemical addi-
  14. 14. 8D - 14 IGNITION SYSTEMS ZJ Fig. 24 Electrode Gap Bridging Fig. 26 Chipped Electrode Insulatortives in certain fuels. These additives are designed to has the correct heat range rating for the engine. De-change the chemical nature of deposits and decrease termine if ignition timing is over advanced, or ifspark plug misfire tendencies. Notice that accumula- other operating conditions are causing engine over-tion on the ground electrode and shell area may be heating. (The heat range rating refers to the operat-heavy, but the deposits are easily removed. Spark ing temperature of a particular type spark plug.plugs with scavenger deposits can be considered nor- Spark plugs are designed to operate within specificmal in condition and can be cleaned using standard temperature ranges. This depends upon the thick-procedures. ness and length of the center electrodes porcelain in- sulator.) Fig. 25 Scavenger Deposits Fig. 27 Preignition DamageCHIPPED ELECTRODE INSULATOR A chipped electrode insulator usually results from SPARK PLUG OVERHEATINGbending the center electrode while adjusting the Overheating is indicated by a white or gray centerspark plug electrode gap. Under certain conditions, electrode insulator that also appears blistered (Fig.severe detonation can also separate the insulator 28). The increase in electrode gap will be consider-from the center electrode (Fig. 26). Spark plugs with ably in excess of 0.001 inch per 1000 miles of opera-this condition must be replaced. tion. This suggests that a plug with a cooler heat range rating should be used. Over advanced ignitionPREIGNITION DAMAGE timing, detonation and cooling system malfunctions Preignition damage is usually caused by excessive can also cause spark plug overheating.combustion chamber temperature. The center elec-trode dissolves first and the ground electrode dis- SPARK PLUG SECONDARY CABLESsolves somewhat latter (Fig. 27). Insulators appear 5.2L V-8 Engine Only: Spark plug heat shieldsrelatively deposit free. Determine if the spark plug are pressed into the cylinder head to surround each
  15. 15. ZJ IGNITION SYSTEMS 8D - 15 around the spark plug insulator. Loose cable connec- tions can cause corrosion and increase resistance, re- sulting in shorter cable service life. Clean the high tension cables with a cloth moist- ened with a nonflammable solvent and wipe dry. Check for brittle or cracked insulation. When testing secondary cables for damage with an oscilloscope, follow the instructions of the equipment manufacturer. If an oscilloscope is not available, spark plug cables may be tested as follows: CAUTION: Do not leave any one spark plug cable disconnected for longer than necessary during test- ing. This may cause possible heat damage to the catalytic converter. Total test time must not exceed Fig. 28 Spark Plug Overheating ten minutes.spark plug cable boot and spark plug (Fig. 29). Theseshields protect the spark plug boots from damage With the engine not running, connect one end of a(due to intense engine heat generated by the exhaust test probe to a good ground. Start the engine and runmanifolds) and should not be removed. After the the other end of the test probe along the entirespark plug cable has been installed, the lip of the ca- length of all spark plug cables. If cables are crackedble boot should have a small air gap to the top of the or punctured, there will be a noticeable spark jump from the damaged area to the test probe. The cableheat shield (Fig. 29). running from the ignition coil to the distributor cap can be checked in the same manner. Cracked, dam- aged or faulty cables should be replaced with resis- tance type cable. This can be identified by the words ELECTRONIC SUPPRESSION printed on the cable jacket. Use an ohmmeter to test for open circuits, exces- sive resistance or loose terminals. Remove the dis- tributor cap from the distributor. Do not remove cables from cap. Remove cable from spark plug. Connect ohmmeter to spark plug terminal end of ca- ble and to corresponding electrode in distributor cap. Resistance should be 250 to 1000 Ohms per inch of cable. If not, remove cable from distributor cap tower and connect ohmmeter to the terminal ends of cable. If resistance is not within specifications as found in the Spark Plug Cable Resistance chart, replace the Fig. 29 Heat Shields—5.2L V-8 Engine cable. Test all spark plug cables in this manner.TESTING SPARK PLUG CABLE RESISTANCE Spark plug cables are sometimes referred to as sec-ondary ignition cables or secondary wires. The cablestransfer electrical current from the distributor to in-dividual spark plugs at each cylinder. The spark plugcables are of nonmetallic construction and have abuilt in resistance. The cables provide suppression ofradio frequency emissions from the ignition system. Check the high-tension cable connections for good To test ignition coil-to-distributor cap cable, do notcontact at the ignition coil, distributor cap towers remove the cable from the cap. Connect ohmmeter toand spark plugs. Terminals should be fully seated. rotor button (center contact) of distributor cap andThe terminals and spark plug covers should be in terminal at ignition coil end of cable. If resistance isgood condition. Terminals should fit tightly to the ig- not within specifications as found in the Spark Plugnition coil, distributor cap and spark plugs. The Cable Resistance chart, remove the cable from thespark plug cover (boot) of the cable should fit tight distributor cap. Connect the ohmmeter to the termi-
  16. 16. 8D - 16 IGNITION SYSTEMS ZJnal ends of the cable. If resistance is not within spec- be found in the General Diagnosis sections ofifications as found in the Spark Plug Cable Group 14, Fuel System. For numeric flash lampResistance chart, replace the cable. Inspect the igni- code charts, refer to Diagnostic Trouble Codetion coil tower for cracks, burns or corrosion. (DTC). This can also be found in the General For removal and installation of spark plug cables, Diagnosis sections of Group 14, Fuel System.refer to Spark Plug Secondary Cables in the Compo-nent Removal/Installation section.THROTTLE POSITION SENSOR TEST For an operational description, diagnosis and re-moval/installation procedures, refer to Group 14,Fuel System.OXYGEN SENSOR TESTS For an operational description, diagnostics and re-moval/installation procedures, refer to Group 14,Fuel Systems, in this manual.ON-BOARD DIAGNOSTICSFOR CERTAIN IGNITION SYSTEMCOMPONENTS The powertrain control module (PCM) performs anOn-Board Diagnostic (OBD) check for certain ignitionsystem components on all vehicles. This is done bysetting a diagnostic trouble code (DTC). A DTC can be obtained in two different ways. Oneof the ways is by connecting the DRB scan tool to thedata link connector. This connector is located in the Fig. 30 Data Link Connector—Typicalengine compartment (Fig. 30). Refer to the appropri-ate Powertrain Diagnostic Procedures service manualfor operation of the DRB scan tool. The other way isto cycle the ignition key and observe the malfunctionindicator lamp (MIL). The MIL lamp is displayed onthe instrument panel as the CHECK ENGINE lamp(Fig. 31). This lamp will flash a numeric code. If anumeric code number 11 (for the crankshaft positionsensor) or 42 (for the ASD relay) is observed, a prob-lem has been found in the ignition system. Note that the CHECK ENGINE lamp will illumi-nate initially for approximately two seconds eachtime the ignition key is turned to the ON position.This is done for a bulb test. For a complete operational description of allDTC’s, for accessing a DTC and for erasing aDTC, refer to On-Board Diagnostics. This can Fig. 31 Check Engine Lamp Location
  17. 17. ZJ IGNITION SYSTEMS 8D - 17 COMPONENT REMOVAL/INSTALLATION INDEX page pageAutomatic Shutdown (ASD Relay . . .. . . . . . . . . . . 17 Intake Manifold Air Temperature Sensor . . . . . . . . . 25Camshaft Position Sensor . . . . . . . .. . . . . . . . . . . 17 Manifold Absolute Pressure (MAP) Sensor . . . . . . . 25Crankshaft Position Sensor . . . . . . .. . . . . . . . . . . 18 Oxygen (O2S) Sensor . . . . . . . . . . . . . . . . . . . . . . 26Distributors . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 20 Powertrain Control Module (PCM) . . . . . . . . . . . . . 26Engine Coolant Temperature Sensor . . . . . . . . . . . 20 Spark Plug Secondary Cables . . . . . . . . . . . . . . . . 28General Information . . . . . . . . . . . .. . . . . . . . . . . 17 Spark Plugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Ignition Coil . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 25 Throttle Position Sensor (TPS) . . . . . . . . . . . . . . . 28GENERAL INFORMATION INSTALLATION This section of the group, Component Removal/In- (1) Inspect the relay terminals in the PDC and re-stallation, will discuss the removal and installation pair as necessary.of ignition system components. (2) Push the relay into the connector. For basic ignition system diagnostics and service (3) Install the relay cover.adjustments, refer to the Diagnostics/Service Proce- (4) Connect battery cable at battery.dures section of this group. For system operation and component identification, CAMSHAFT POSITION SENSORrefer to the Component Identification/System Opera- The camshaft position sensor is located in the dis-tion section of this group. tributor (Fig. 2).AUTOMATIC SHUTDOWN (ASD) RELAY The ASD relay is installed in the power distribu-tion center (PDC) (Fig. 1). Relay location is printedon the PDC cover. Fig. 2 Camshaft Position Sensor—Typical REMOVAL—4.0L 6-CYLINDER ENGINE Distributor removal is not necessary to remove camshaft position sensor. (1) Disconnect negative battery cable at battery. (2) Remove distributor cap from distributor (two screws). (3) Disconnect camshaft position sensor wiring harness from main engine wiring harness. (4) Remove distributor rotor from distributor shaft. (5) Lift the camshaft position sensor assembly Fig. 1 Power Distribution Center from the distributor housing (Fig. 2).REMOVAL (1) Disconnect negative battery cable at battery. INSTALLATION (2) Remove the PDC cover. (1) Install camshaft position sensor to distributor. (3) Remove the relay by lifting straight up. Align sensor into notch on distributor housing.
  18. 18. 8D - 18 IGNITION SYSTEMS ZJ (2) Connect wiring harness. (3) Install rotor. (4) Install distributor cap. Tighten mountingscrews. (5) Connect negative battery cable at battery.REMOVAL—5.2L V-8 ENGINE Distributor removal is not necessary to removecamshaft position sensor. (1) Disconnect negative battery cable at battery. (2) Remove coil high-tension cable and all sparkplug cables at distributor cap. Note and mark posi-tion of cables (Fig. 3) before removal. Fig. 4 Crankshaft Position Sensor—4.0L Engine With Manual Transmission (1) Near the rear of the intake manifold, discon- nect the pigtail harness on the sensor from the main electrical harness. (2) Raise and support the vehicle. (3) Remove the two sensor mounting bolts (Fig. 4). (4) Remove the sensor. (5) Remove clip from sensor wire harness. INSTALLATION (1) Install the sensor flush against the opening in Fig. 3 Engine Firing Order—5.2L V-8 Engine the transmission housing. (2) Install and tighten the two sensor mounting (3) Remove distributor cap from distributor (two bolts to 19 N⅐m (14 ft. lbs.) torque.screws). (4) Disconnect camshaft position sensor wiring CAUTION: The two bolts used to secure the sensorharness from main engine wiring harness. to the transmission are specially machined to cor- (5) Remove distributor rotor from distributor shaft. rectly space the unit to the flywheel. Do not attempt (6) Lift the camshaft position sensor assembly to install any other bolts.from the distributor housing (Fig. 2). (3) Lower the vehicle.INSTALLATION (4) Connect the electrical connector to the sensor. (1) Install camshaft position sensor to distributor. (5) Install clip on sensor wire harness.Align sensor into notch on distributor housing. (2) Connect wiring harness. REMOVAL—4.0L ENGINE WITH AUTOMATIC (3) Install rotor. TRANSMISSION (4) Install distributor cap. Tighten mounting The crankshaft position sensor is mounted to thescrews. transmission bellhousing with a single bolt. It is lo- (5) Install spark plug cables in correct firing order cated at the left/rear side of the engine block (Fig. 5).(Fig. 3) to distributor cap. Be sure all spark plug ca- The slotted adjustment hole is not used for the 1995bles are firmly connected into distributor cap towers. model year. (6) Connect negative battery cable at battery. (1) Near the rear of the intake manifold, discon-CRANKSHAFT POSITION SENSOR nect the pigtail harness (on the sensor) from the main electrical harness.REMOVAL—4.0L 6-CYLINDER ENGINE WITH (2) Remove the nut holding sensor wire clip to fuelMANUAL TRANSMISSION rail mounting stud. The crankshaft position sensor is mounted to the (3) Remove the one sensor mounting bolt.transmission bellhousing with two bolts at the left/ (4) Remove the sensor.rear side of the engine block (Fig. 4). (5) Remove clip from sensor wire harness.
  19. 19. ZJ IGNITION SYSTEMS 8D - 19 Fig. 6 Crankshaft Position Sensor—5.2L V-8 Engine Fig. 5 Crankshaft Position Sensor—4.0L Engine With Automatic TransmissionINSTALLATION (1) Install the sensor into the access hole on thetransmission. (2) Install sensor mounting bolt (Fig. 5). (3) Tighten sensor mounting bolt to 6-to-8 N⅐m (50-to-70 in. lbs.) torque. (4) Connect the electrical connector to sensor. (5) Install the clip to sensor wire harness. (6) Install clip over fuel rail mounting stud. Installclip mounting nut.REMOVAL—5.2L V-8 ENGINE The sensor is bolted to the top of the cylinder blocknear the rear of right cylinder head (Fig. 6). (1) Remove the spark plug cable loom and spark Fig. 7 Exhaust Manifold Heat Shield—5.2L Engineplug cables from valve cover mounting stud at rear ofright valve cover (Fig. 6). Position spark plug cables (8) Loosen EGR tube mounting nut at intake man-to top of valve cover. ifold (Fig. 6). (2) Remove the right exhaust manifold heat shield (9) Remove 2 EGR tube mounting bolts at exhaustnuts/bolts and remove heat shield (Fig. 7). manifold (Fig. 6) and remove EGR tube. Discard old (3) Disconnect 2 hoses at exhaust gas recirculation gasket at exhaust manifold.(EGR) valve. Note position of hoses at EGR valve be- (10) Disconnect crankshaft position sensor pigtailfore removal. harness from main wiring harness. (4) Disconnect electrical connector and hoses at (11) Remove 2 sensor (recessed hex head) mount-EGR valve control. Note position of hoses at valve ing bolts (Fig. 6) and remove sensor.control before removal. (5) Remove 2 EGR valve mounting bolts (Fig. 6) INSTALLATION—5.2L ENGINEand remove EGR valve. Discard old EGR gasket. (1) Position crankshaft position sensor to engine (6) Disconnect electrical connector at engine oil and install mounting bolts. Tighten bolts to 8 N⅐mpressure sending unit. (70 in. lbs.) torque. (7) To prevent damage to oil pressure sending unit, (2) Connect main harness electrical connector toa special tool, such as number C-4597 must be used sensor.(Fig. 8). Remove sending unit from engine.
  20. 20. 8D - 20 IGNITION SYSTEMS ZJ DISTRIBUTORS All distributors contain an internal oil seal that prevents oil from entering the distributor housing. The seal is not serviceable. The camshaft position sensor is located in the distributor on all engines. 4.0L 6-Cylinder Engine Only: Factory replace- ment distributors are equipped with a plastic align- ment pin already installed. The pin is located in an access hole on the bottom of the distributor housing (Fig. 9). It is used to temporarily lock the rotor to the cylinder number 1 position during installation. The pin must be removed after installing the distributor. Fig. 8 Oil Pressure Sending Unit—Removal/ Installation (3) Clean the EGR tube and exhaust manifold (atEGR tube mounting point) of any old gasket mate-rial. (4) Install a new gasket to exhaust manifold end ofEGR tube and install EGR tube to both manifolds.Tighten tube mounting nut at intake manifold.Tighten 2 mounting bolts at exhaust manifold to 23N⅐m (204 in. lbs.) torque. (5) Coat the threads of the oil pressure sendingunit with thread sealant. Do not allow any of thethread sealant to get into the sending unit opening, Fig. 9 Plastic Alignment Pin—4.0L Engineor the opening at the engine. Install sending unit to The camshaft position sensor is located in the dis-engine and tighten to 14 N⅐m (130 in. lbs.) torque. In- tributor on all engines (Fig. 10). For removal/instal-stall electrical connector to sending unit. lation procedures, refer to Camshaft Position Sensor (6) Clean the intake manifold and EGR valve of in this group. Distributor removal is not necessaryany old gasket material. for sensor removal. (7) Install a new EGR valve gasket at intake man- Refer to figure 11 for an exploded view of the dis-ifold. tributor with the 4.0L engine. (8) Install EGR valve to intake manifold. Tighten 2 4.0L 6-Cylinder Engine Only: A fork with a slotEGR bolts to 23 N⅐m (200 in. lbs.) torque. is supplied on the bottom of the distributor housing (9) Position EGR valve control and install its elec- where the housing base seats against the enginetrical connector. Connect hoses between EGR valve block (Fig. 11). The centerline of the slot aligns withand EGR valve control. Connect hose between main the distributor holddown bolt hole in the engineengine vacuum harness and valve control. block. Because of the fork, the distributor cannot be (10) Install spark plug cable loom and spark plug rotated. Distributor rotation is not necessary as allcables to valve cover mounting stud. ignition timing requirements are handled by the (11) Install heat shield at right exhaust manifold. powertrain control module (PCM). Do not attempt to modify this fork to attain ignition timing.ENGINE COOLANT TEMPERATURE SENSOR All Engines: The rotational position of the distrib- For an operational description, diagnosis and re- utor determines fuel synchronization only. It does notmoval/installation procedures, refer to Group 14, determine ignition timing.Fuel System.
  21. 21. ZJ IGNITION SYSTEMS 8D - 21 (5) Remove the cylinder number 1 spark plug. (6) Hold a finger over the open spark plug hole. Rotate the engine at the vibration dampener bolt un- til compression (pressure) is felt. Slowly continue to rotate the engine. Do this until the timing index mark on the vibration damper pul- ley aligns with the top dead center (TDC) mark (0 degree) on timing degree scale (Fig. 12). Always ro- tate the engine in direction of normal rotation. Do not rotate the engine backward to align the timing marks. Fig. 10 Camshaft Position Sensor—All Engines— Typical Fig. 12 Align Timing Marks (7) Remove the distributor holddown bolt and clamp (Fig. 11). (8) Remove the distributor from engine by slowly lifting straight up. Note that the rotor will rotate slightly in a counter- clockwise direction while lifting up the distributor. The oil pump gear will also rotate slightly in a coun- terclockwise direction while lifting up the distributor. This is due to the helical cut gears on the distributor and camshaft. Note the removed position of the rotor during dis- tributor removal. During installation, this will be re- Fig. 11 Distributor—4.0L Engines—Typical ferred to as the Pre-position.REMOVAL—4.0L 6-CYLINDER ENGINE Observe the slot in the oil pump gear through the (1) Disconnect the negative battery cable at the hole on the side of the engine. It should be slightlybattery. before (counterclockwise of) the 11 o’clock position (2) Disconnect coil secondary cable at coil. (Fig. 13). (9) Remove and discard the old distributor-to-en- (3) Remove distributor cap from distributor (2 gine block gasket (Fig. 11).screws). Do not remove cables from cap. Do not re-move rotor. INSTALLATION—4.0L 6-CYLINDER ENGINE (4) Disconnect the distributor wiring harness from (1) If the engine crankshaft has been rotated afterthe main engine harness. distributor removal, cylinder number 1 must be re-
  22. 22. 8D - 22 IGNITION SYSTEMS ZJ Fig. 13 Slot At 11 O’clock Position—4.0L Engineturned to its proper firing stroke. Refer to the previ-ous REMOVAL steps number 5 and 6. These stepsmust be done before installing distributor. (2) Check the position of the slot on the oil pumpgear. It should be just slightly before (counterclock- Fig. 14 Pin Alignment Holeswise of) the 11 o’clock position (Fig. 13). If not, placea flat blade screwdriver into the oil pump gear and shaft. When the distributor is fully seated to the en-rotate it into the proper position. gine block, the centerline of the base slot should be (3) Factory replacement distributors are equipped aligned to the clamp bolt mounting hole on the en-with a plastic alignment pin already installed (Fig. gine (Fig. 16). The rotor should also be pointed at the9). This pin is used to temporarily hold the rotor to 5 o’clock position.the cylinder number 1 firing position during distrib- It may be necessary to rotate the rotor and distrib-utor installation. If this pin is in place, proceed to utor shaft (very slightly) to engage the distributorstep number 8. If not, proceed to step number 4. shaft with the slot in the oil pump gear. The same (4) If the original distributor is to be reinstalled, may have to be done to engage the distributor gearsuch as during engine overhaul, the plastic pin will with the camshaft gear.not be available. A 3/16 inch drift pin punch tool maybe substituted for the plastic pin. (5) Remove the camshaft position sensor from thedistributor housing. Lift straight up. (6) Four different alignment holes are provided onthe plastic ring (Fig. 14). For this application, use‘‘4.0L 6-CYLINDER ENGINE ALIGN. HOLE’’ asshown in figure 14. Rotate the distributor shaft and install the pinpunch tool through the proper alignment hole in theplastic ring (Fig. 14) and into the mating access holein the distributor housing. This will prevent the dis-tributor shaft and rotor from rotating. (7) Clean the distributor mounting hole area of theengine block. (8) Install a new distributor-to-engine block gasket(Fig. 11). (9) Install the rotor to the distributor shaft. (10) Pre-position the distributor into the enginewhile holding the centerline of the base slot in the 1o’clock position (Fig. 15). Continue to engage the dis-tributor into the engine. The rotor and distributorwill rotate clockwise during installation. This is due Fig. 15 Distributor Pre-position—4.0L Engineto the helical cut gears on the distributor and cam-
  23. 23. ZJ IGNITION SYSTEMS 8D - 23 (17) Connect the distributor wiring harness to the main engine harness. (18) Connect battery cable to battery. REMOVAL—5.2L V-8 ENGINE CAUTION: Base ignition timing is not adjustable on the 5.2L V-8 engine. Distributors do not have built in centrifugal or vacuum assisted advance. Base igni- tion timing and timing advance are controlled by the powertrain control module (PCM). Because a conventional timing light can not be used to adjust distributor position after installation, note position of distributor before removal. (1) Disconnect negative battery cable at battery. (2) Remove coil high-tension cable and all spark plug cables at distributor cap. Note and mark posi- tion of cables (Fig. 17) before removal. Fig. 16 Distributor Engaged Position—4.0L Engine The distributor is correctly installed when:• the rotor is pointed at the 5 o’clock position.• the plastic alignment pin (or pin punch tool) is stillinstalled to distributor.• the number 1 cylinder piston is set at top deadcenter (TDC) (compression stroke).• the centerline of the slot at the base of the distrib-utor is aligned to the centerline of the distributorholddown bolt hole on the engine. In this position,the holddown bolt should easily pass through the slotand into the engine. No adjustments are necessary. Proceed to nextstep. Fig. 17 Engine Firing Order—5.2L Engine (11) Install the distributor holddown clamp and (3) Remove distributor cap from distributor (twobolt. Tighten the bolt to 23 N⅐m (17 ft. lbs.) torque. screws). (12) Remove the pin punch tool from the distribu- (4) Mark the position of distributor housing in re-tor. Or, if the plastic alignment pin was used, remove lationship to engine or dash panel. This is done toit straight down from the bottom of the distributor. aid in installation.Discard plastic pin. Before distributor is removed, the number one cyl- (13) If removed, install the camshaft position sen- inder must be brought to the top dead center (TDC)sor to the distributor. Align the wiring harness grom- firing position.met to the notch in the distributor housing. (5) Attach a socket to the crankshaft vibration (14) Install the rotor. damper mounting bolt. (6) Slowly rotate engine clockwise, as viewed fromCAUTION: If the distributor cap is incorrectly posi- front, until indicating mark on crankshaft vibrationtioned on distributor housing, the cap or rotor may damper is aligned to 0 degree (TDC) mark on timingbe damaged when engine is started. chain cover (Fig. 18). (7) The distributor rotor should now be aligned to (15) Install the distributor cap. Tighten distributor the CYL. NO. 1 alignment mark (stamped) into thecap holddown screws to 3 N⅐m (26 in. lbs.) torque. camshaft position sensor (Fig. 19). If not, rotate the (16) If removed, install the spark plug cables to crankshaft through another complete 360 degreethe distributor cap. For proper firing order, refer to turn. Note the position of the number one cylinderthe Specifications section at the end of this group. spark plug cable (on the cap) in relation to rotor. Ro-See Engine Firing Order. tor should now be aligned to this position.
  24. 24. 8D - 24 IGNITION SYSTEMS ZJ Fig. 18 Damper-To-Timing Chain Cover Alignment Fig. 20 Distributor Holddown Clamp—5.2L Engine Marks—5.2L Engine (1) Clean top of cylinder block for a good seal be- tween distributor base and block. (2) Lightly oil the rubber o-ring seal on the distrib- utor housing. (3) Install rotor to distributor shaft. (4) Position distributor into engine to its original position. Engage tongue of distributor shaft with slot in distributor oil pump drive gear. Position rotor to the number one spark plug cable position. (5) Install distributor holddown clamp and clamp bolt. Do not tighten bolt at this time. (6) Rotate the distributor housing until rotor is aligned to CYL. NO. 1 alignment mark on the cam- shaft position sensor (Fig. 19). (7) Tighten clamp holddown bolt (Fig. 20) to 22.5 N⅐m (200 in. lbs.) torque. Fig. 19 Rotor Alignment Mark—5.2L Engine (8) Connect camshaft position sensor wiring har- ness to main engine harness. (8) Disconnect camshaft position sensor wiring (9) Install distributor cap. Tighten mountingharness from main engine wiring harness. screws. (9) Remove distributor rotor from distributor shaft. (10) Install spark plug cables in correct firing or- (10) Remove distributor holddown clamp bolt and der (Fig. 17) to distributor cap. Be sure all sparkclamp (Fig. 20). Remove distributor from vehicle. plug cables are firmly connected into distributor cap towers.CAUTION: Do not crank engine with distributor re- (11) Refer to the following, Checking Distributormoved. Distributor/crankshaft relationship will be Position.lost. CHECKING DISTRIBUTOR POSITION—5.2L ENGINE ONLYINSTALLATION—5.2L ENGINE To verify correct distributor rotational position, If engine has been cranked while distributor is re- connect the DRB scan tool to the data link connector.moved, establish the relationship between distributor The data link connector is located in the engine com-shaft and number one piston position as follows: partment. Gain access to the SET SYNC screen on Rotate crankshaft in a clockwise direction, as the DRB.viewed from front, until number one cylinder pistonis at top of compression stroke (compression should WARNING: WHEN PERFORMING THE FOLLOWINGbe felt on finger with number one spark removed). TEST, THE ENGINE WILL BE RUNNING. BE CARE-Then continue to slowly rotate engine clockwise until FUL NOT TO STAND IN LINE WITH THE FANindicating mark (Fig. 18) is aligned to 0 degree BLADES OR FAN BELT. DO NOT WEAR LOOSE(TDC) mark on timing chain cover. CLOTHING.
  25. 25. ZJ IGNITION SYSTEMS 8D - 25 Follow the directions on the DRB screen and start REMOVAL—5.2L V-8 ENGINEthe engine. With the engine running, the words IN The ignition coil is mounted to a bracket near theRANGE should appear on the screen along with 0°. front of the right engine cylinder head on 5.2L en-This indicates correct distributor position. gines (Fig. 22). If a plus (+) or a minus (-) is displayed next to thedegree number, and/or the degree displayed is notzero, loosen but do not remove the distributor hold-down clamp bolt. Rotate the distributor until INRANGE appears on the screen. Continue to rotatethe distributor until achieving as close to 0° as pos-sible. After adjustment, tighten clamp bolt to 22.5N⅐m (200 in. lbs.) torque. The degree scale on the SET SYNC screen of theDRB is referring to fuel synchronization only. It isnot referring to ignition timing. Because of this,do not attempt to adjust ignition timing using thismethod. Rotating the distributor will have no effecton ignition timing. All ignition timing values are con-trolled by the powertrain control module (PCM).IGNITION COIL Fig. 22 Ignition Coil—5.2L Engine—Typical The ignition coil is an epoxy filled type. If the coil (1) Disconnect the wiring and secondary cable fromis replaced, it must be replaced with the same type. the ignition coil (Fig. 22).REMOVAL—4.0L 6-CYLINDER ENGINE WARNING: DO NOT REMOVE THE COIL MOUNTING The ignition coil is mounted to the right side of the BRACKET-TO-CYLINDER HEAD MOUNTING BOLTS.4.0L engine block next to the distributor (Fig. 21). THE COIL MOUNTING BRACKET IS UNDER ACCES- SORY DRIVE BELT TENSION. IF THIS BRACKET IS TO BE REMOVED FOR ANY REASON, ALL BELT TENSION MUST FIRST BE RELIEVED. REFER TO THE BELT SECTION OF GROUP 7, COOLING SYS- TEM. (2) Remove ignition coil from coil mounting bracket (two bolts). INSTALLATION—5.2L ENGINE (1) Install the ignition coil to coil bracket. If nuts and bolts are used to secure coil to coil bracket, tighten to 11 N⅐m (100 in. lbs.) torque. If the coil mounting bracket has been tapped for coil mounting bolts, tighten bolts to 5 N⅐m (50 in. lbs.) torque. (2) Connect all wiring to ignition coil. Fig. 21 Ignition Coil—4.0L Engine INTAKE MANIFOLD AIR TEMPERATURE SENSOR (1) Disconnect the ignition coil secondary cable For an operational description, diagnosis and re-from ignition coil (Fig. 21). moval/installation procedures, refer to the Diagnosis (2) Disconnect engine harness connector from igni- sections of Group 14, Fuel System.tion coil. (3) Remove ignition coil mounting bolts. Removecoil. MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR For an operational description, diagnosis and re-INSTALLATION—4.0L ENGINE moval/installation procedures, refer to Group 14, (1) Install ignition coil to bracket on cylinder block Fuel System.with mounting bolts. (2) Connect engine harness connector to coil. (3) Connect ignition coil cable to ignition coil.
  26. 26. 8D - 26 IGNITION SYSTEMS ZJOXYGEN (O2S) SENSOR For an operational description, diagnostics and re-moval/installation procedures, refer to Group 14,Fuel Systems, in this manual.POWERTRAIN CONTROL MODULE (PCM) The PCM is located on the cowl panel in the right/rear side of the engine compartment (Fig. 23). Fig. 24 Coolant Reserve/Overflow Tank Mounting Fig. 23 PCM LocationREMOVAL (1) Disconnect the negative battery cable at bat-tery. (2) Remove the coolant reserve/overflow tank (onebolt and two nuts) (Fig. 24) (3) Loosen the 60-Way connector mounting bolt(Fig. 25). (4) Remove the electrical connector by pullingstraight back. (5) Remove the three PCM mounting bolts (Fig.25). (6) Remove PCM. Fig. 25 PCM MountingINSTALLATION round each cable boot and spark plug (Fig. 26). These (1) Check the pins in the PCM 60-way electrical shields protect the spark plug boots from damageconnector for damage. Repair as necessary. (due to intense engine heat generated by the exhaust (2) Install PCM. Tighten three mounting bolts to 1 manifolds) and should not be removed. After theN⅐m (9 in. lbs.) torque. spark plug cable has been installed, the lip of the ca- (3) Engage 60-way connector into PCM. Tighten ble boot should have a small air gap to the top of theconnector mounting bolt to 4 N⅐m (35 in. lbs.) torque. heat shield (Fig. 26). (4) Install coolant reserve/overflow tank (Fig. 24). If removal of the heat shield(s) is necessary, remove (5) Connect negative cable to battery. the spark plug cable and compress the sides of shieldSPARK PLUGS for removal. Each shield is slotted to allow for com- 5.2L V-8 ENGINE ONLY: Spark plug cable heat pression and removal. To install the shields, alignshields are pressed into the cylinder head to sur-

×