Elect Diag

3.  Road test and VERIFY
customer concern
 Document shift problems
found during roadtest on RO
 ANALYIZE shift problems
 Check external adjustments
and engine condition
▪ Fluid condition
▪ Shift cable adjustment
▪ TV cable adjustment
▪ Engine vacuum
▪ Kick down rod adjustment
▪ Pressure test and stall test

4.  ISOLATE the problem
 Determine if the concern can be fixed with the
trans in the vehicle or if it has to come out
 VERIFY repair
 Road test to verify fix

5.  VERIFY concern
 Road test and document
shift problems on RO
 Check fluid condition
 Check for leaks
 Check for add-on chips
or programmers
▪ “Chipping” the processor
will void powertrain
warranty.
 Scan for codes
 Check TSB’s and SSM’s

6.  ANALYIZE the concern
 Determine if Self Test code in a Hard or Soft code
▪ Hard Code = Electrical fault present at the time of self
test
▪ Soft Code = Intermittent code OR slip code found by
computer logic
 When do you follow Trouble Tree? Soft code or
Hard Code

7.  No DTC’s but trans has symptom
 Proper verification critical!

8.  No code or symptom
 Intermittent Concern
 Punt?
 Call it NPF?
 Call customer and gather
more information
 Ask to road test home
 Check TSB’s and SSM’s
 Call Tech Line
 DONOT ATTEMPT FIX
UNTILL YOU HAVE
VERIFIED CONCERN!

9.  Isolate concern
 Scan Tool
▪ MFG
▪ Generic
 DTC retrieval
▪ Always diagnose U codes first
▪ Start with 1st
code retrieved (ECM prioritizes codes)
▪ One fault can cause multiple codes

10.  Scan Tool Cont.
 Active
Command/Special
Functions
▪ Use scan tool to “force
shift”
▪ A way to determine if fault
is “logic” related or part
failure
▪ In-Line tester AKA Break
Out Box (BOB)
 Eliminates ECM

11.  Scan Tool Cont.
 PID Data
▪ PID Data is like a film strip
▪ Use PID data and ETM to
eliminate possible causes
▪ Diagram
 Snap Shot
▪ Limit PID’s because of
refresh rate
▪ Freeze Frame
▪ Honda Snap Shot w/DTC

12.  Pressure testing
 Specifications
▪ Normal Trans Temp and operation
▪ Each gear should be tested
 Test Ports
▪ Single test port
▪ Usually Line pressure
▪ Multiple test ports
▪ Line, TV, individual clutch circuits; helps narrow down fault
▪ Must hook up gauge to specific apply device and engage that
gear to get readings

13.  Stall testing
 Checks converter and apply device in selected gear
 TEST FOR 5 SECONDS MAX and allow for cool down
between gears! Chock wheels and set park brake!
▪ Low stall test RPM
▪ Base engine
▪ Faulty stator one way clutch
▪ ECM rev limiter/protection
▪ High stall speed
▪ Slipping clutches
▪ Incorrect converter

14.  TCC application check
 Confirm on road test with scan tool
▪ Check for 200rpm drop
▪ Monitor TCC Slip PID during road test to verify
 Use BOB in stall and in gear
▪ Engine should stall when TCC applied

15.  Electrical Test Tools
 DVOM - Digital Volt/Ohm Meter
▪ Reads Voltage, Resistance, Amperage
▪ Slow refresh rate
▪ Can’t measure voltage over time
 DSO – Digital Storage Oscilloscope
▪ Reads Voltage over time
 Test lamp (low impedance)
▪ Only for Battery fed circuits NEVER ECM CIRCUITS!
 Logic Probe (high impedance)
▪ Good for ECM and Battery fed circuits

16.  What to test
 Available Voltage
 Hook up in parallel with circuit live
▪ Check battery 1st
for Base Line
▪ Check available voltage at load
▪ Should be within .05V of battery voltage
 Relay
 Resistance
 Hook in parallel with component/circuit isolated
▪ Only when required by manual
▪ Service manual logic
▪ Ohm checks can fool you!
▪ Difference between ohms and volt drop
 Shift Solenoid

17.  How to test
 Volt Drops
▪ Parallel circuit/load with circuit live
▪ .030v PCM circuit
▪ All of source voltage if last load in circuit
 Voltage Drops should be used instead of Ohm
checks!

18.  What to test cont.
 Amperage
 Hook up in series if using DVOM circuit live
 Sample circuit with inductive probe and DSO
▪ Not very common
▪ Can show resistance in PWM circuit when monitored
with DSO
PC solenoid

19.  How to test
 Shorts – Ohm test
▪ Shorts to ground
▪ Shorts to power
▪ Shorts to another circuit

20.  DTC’s can indicate a slip fault
 Used Apply Charts to identify possible causes
 Use the apply chart to determine the possible
cause:
 You verify the vehicle will not shift out of 2nd
 There is engine braking in Manual 2nd
 Code P0755, P0782
 The vehicle will not shift to 4th
 Concern is verified
 Code p0734

21.  FWD Wheel bearing
VS final drive bearing
 Wheel bearing will
change pitch on turns
 Final drive carrier
bearings will change
noise w/ torque
 Use chassis ears to
verify source

22.  Planetary noise
 Verify gear noise comes from
 Use powerflow chart to determine planetary
 Noise in 1st
and Rev normal on most vehicles

23.  Torque Converter Balance
 Vibration felt that is proportional to engine speed
 Use Sirometer or EVA to diagnose
 Vibration may change with converter lock up
 Drive Shaft Vibration
 Vibration will present itself at above 45mph
 Vibration will be proportional to vehicle/drive shaft
speed
 Can be caused by work tail shaft bushing

24.  Rear Axle Noise
 Usually a howl noise
 Noise peaks at 45-60mph
 Noise will change with load
 Rear axle bearing noise can change with
direction/load

25.  Determine what is
leaking first by
checking color of oil
 PS fluid can look like
ATF
 Burnt ATF can look like
engine oil

26.  Start by cleaning the
obvious oil and above
what could be the leak
 Add specific oil dye
 Road test
 Re-check for leaks with
black light
 Determine source of
leak AND WHY
SEAL/GASKET/SEAM
 Failed!