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  • 1. ZJ HORNS 8G - 1 HORNS CONTENTS page pageDIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 SERVICE PROCEDURES ................... 2GENERAL INFORMATION . . . . . . . . . . . . . . . . . . 1 GENERAL INFORMATION Following are general descriptions of the major One side of the horn relay electromagnetic coil re-components in the Grand Cherokee horn system. Re- ceives battery voltage at all times. When a hornfer to Group 8W - Wiring Diagrams for complete cir- switch is depressed, the other side of the relay coil iscuit descriptions and diagrams. grounded. The energized relay coil causes the nor- mally open relay contacts to close, providing batteryHORN SWITCH voltage to the horn. Two horn switches are installed in the steering If a problem is encountered with a continuouslywheel, one on each side of the center-mounted driv- sounding horn, it can usually be quickly resolved byer’s airbag module. When either switch is depressed removing the horn relay from the relay center untilit completes a circuit to ground for the coil side of the further diagnosis is completed.horn relay. The steering wheel and steering columnmust be properly grounded for the horn switches to HORNSfunction. The horn switches are only serviced as a set The standard dual note, diaphragm-type horns arewith their wiring. If either switch should fail, both mounted to a bracket beneath the right radiator clo-switches must be replaced. sure extension panel and forward of the right front inner wheelhouse. They are grounded through theHORN RELAY mounting bracket and are connected in parallel to re- The horn relay is a mini-relay installed in the relay ceive battery feed through the closed contacts of thecenter, which is under a cover inside the glove box. horn relay. DIAGNOSISWARNING: ON VEHICLES EQUIPPED WITH AN AIR- • The normally closed terminal (87A) is connected toBAG, REFER TO GROUP 8M - RESTRAINT SYS- terminal 30 in the de-energized position, but is notTEMS BEFORE ATTEMPTING STEERING WHEEL used for this application.COMPONENT DIAGNOSIS OR SERVICE. FAILURE • The normally open terminal (87) is connected toTO TAKE PROPER PRECAUTIONS COULD RESULT the common feed terminal (30) in the energized posi-IN ACCIDENTAL AIRBAG DEPLOYMENT AND POS- tion. This terminal supplies battery voltage to theSIBLE PERSONAL INJURY. horn. There should be continuity between relay cav- ity 87 and the horn terminal at all times. If not, re- (1) Inspect fuse 13 in fuseblock module and F14 in pair wiring or connections as required.PDC. Replace fuses, as required. • The coil battery terminal (86) is connected to the (2) Remove the horn relay from the relay center. electromagnet in the relay, and battery voltageSee Horn Relay Connections (Fig. 1) and perform the should be present at all times. If battery voltage isfollowing tests. not present at relay cavity 86, check circuit to fuse• The common feed terminal (30) is connected to 13. Repair as required.battery voltage and should be hot at all times. If bat- • The coil ground terminal (85) is connected to thetery voltage is not present at relay cavity 30, check electromagnet in the relay. It is grounded when thecircuit to fuse 13. Repair as required. horn switch is depressed. Check for continuity to
  • 2. 8G - 2 HORNS ZJground at relay cavity 85 with the horn switch de-pressed. If no continuity is found with horn switchdepressed or, if continuity is found with horn switchreleased, repair horn switch or wiring as required.See Horn Switch Remove/Install in this group for ser-vice procedures. If all relay connections check OK, proceed to nextstep. (3) With the horn relay still removed, check thehorn relay by performing the following tests.• A relay in the de-energized position should havecontinuity between terminal 87A and terminal 30,and no continuity between terminal 87 and terminal30.• Resistance value between terminals 85 and 86(electromagnet) is 75Ϯ5 ohms.• Connect a battery to terminals 85 and 86. There Fig. 1 Horn Relay Connectionsshould now be continuity between terminal 87 and (5) Measure the resistance between the hornterminal 30. bracket and a good chassis ground. The meter should If relay fails any of the above tests, replace faulty read zero ohms. If not, clean and tighten ground con-relay. If relay checks OK, reinstall and proceed to nection between horn mounting screw and bracket. Ifnext step. (4) Disconnect wiring at horn terminal. Depress OK, replace faulty horn(s).horn switch. There should be battery voltage at thehorn wiring connector. If not, repair wiring to relay.If OK, proceed to next step. SERVICE PROCEDURESHORN SWITCH REMOVE/INSTALLWARNING: BEFORE BEGINNING ANY AIRBAG SYS-TEM COMPONENT REMOVAL OR INSTALLATION,REMOVE AND ISOLATE THE NEGATIVE (-) CABLEFROM THE BATTERY. THIS IS THE ONLY SUREWAY TO DISABLE THE AIRBAG SYSTEM. FAILURETO DO THIS COULD RESULT IN ACCIDENTAL AIR-BAG DEPLOYMENT AND POSSIBLE INJURY. WAIT 2MINUTES FOR THE RESERVE CAPACITOR TO DIS-CHARGE BEFORE REMOVING OR WORKING ONANY AIRBAG SYSTEM COMPONENTS. (1) Disconnect and isolate the battery negative ca-ble. (2) Remove 4 retaining nuts from back of steering Fig. 2 Horn Switch Remove/Installwheel (Fig. 2). Remove air bag module. (3) Disconnect wire from rear of air bag module. (6) Remove 2 screws and disconnect horn wires lo- (4) Place air bag module on a clean level surface cated in the lower portion of steering wheel. Pushwith pad facing upward. wires through the access holes and remove horn (5) To remove horn switch assembly from steering, switch.pry out 2 trim cover buttons on back of steering (7) Reverse removal procedures to install. Use cau-wheel to access retaining screws for the horn switch. tion not to pinch wires. Tighten airbag module mounting nuts to 1.5 N⅐m (15 in. lbs.) torque.
  • 3. ZJ HORNS 8G - 3HORNS REMOVE/INSTALL (1) Disconnect battery negative cable. (2) Raise and support the vehicle. (3) Remove the splash shield from passenger sideof vehicle. (4) Disconnect wire harness connector from thehorn (Fig. 3). Fig. 4 Relay Center Cover Fig. 3 Horn Remove/Install (5) Remove horn mounting bolt, mounting bracketsand horns. Each horn and bracket is removed as anassembly. (6) Reverse removal procedures to install. Tightenhorn bracket mounting bolt to 30 N⅐m (22 ft. lbs.).HORN RELAY REMOVE/INSTALL (1) Open glove box and remove 3 screws holdingrelay center cover (Fig. 4). Fig. 5 Horn Relay (2) Remove horn relay (Fig. 5) (3) To install, align relay pins with cavities in relaycenter and push relay into place. (4) Install relay center cover.