Diagnostic Strategy

Troubleshooting an electronically-controlled automatic transaxle is simplified by using the proven method of diagnosis. One of the most important things to remember is that there is a definite procedure to follow.

Note: Do not take shortcuts or assume that critical checks or adjustments have already been made.

Follow the procedures as written to avoid missing critical components or steps.

To correctly diagnose a concern have the following publications available:
- Technical Service Bulletins (TSBs)
- Wiring Diagrams

These publications provide the information required when diagnosing transaxle concerns.





Use the Diagnostic Flow Chart as a guide and follow the steps as indicated.

Air Conditioning A/C Clutch
An electromagnetic clutch is energized when the clutch cycling pressure switch closes. The switch is located on the suction accumulator/drier. The closing of the switch completes the circuit to the clutch and draws it into engagement with the compressor driveshaft. When the A/C is engaged, EPC pressure is adjusted to compensate for the additional load on the engine.

Engine Coolant Temperature (ECT) Sensor
The Engine Coolant Temperature (ECT) sensor detects the temperature of the engine coolant and supplies the information to the PCM. The ECT sensor is used to control Torque Converter Clutch (TCC) operation. The ECT is installed in the heater outlet fitting or cooling passage on the engine. For engine control applications, the ECT signal is used to modify ignition timing, EGR flow and air-to-fuel ratio as a function of engine coolant temperature.

Preliminary Inspection
- Know and understand the customer's concern.
- Verify the concern by operating the vehicle.
- Check the fluid levels and condition.
- Check for non-factory add-on items.
- Check shift linkages for correct adjustment.
- Check TSBs regarding the concern.

Diagnostics
- Carry out the on-board diagnostic procedures, Key On/Engine Off (KOEO) and Key On/Engine Running (KOER)
- Record all Diagnostic Trouble Codes (DTCs).
- Repair all non-transaxle codes first.
- Repair all transaxle codes second.
- Erase all continuous codes and attempt to repeat them.
- Repair all continuous codes.
- If only pass codes are obtained, proceed to Diagnosis by Symptom Index for further information and diagnosis.

Follow the diagnostic sequence to diagnose and repair the concern the first time.