Diagnostic Strategy

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

Troubleshooting an electronically-controlled automatic transmission 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.
Follow the procedures as written to avoid missing critical components or steps. To diagnose a concern properly, the technician should have the following publications available:
- Technical Service Bulletins (TSBs).
- Wiring Diagram.
These publications provide the information required when diagnosing transmission concerns.









Using the Diagnostic Flowchart as a guide, follow the steps as indicated.

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

Diagnostics
- Carry out on-board diagnostic procedures Key On/Engine Off (KOEO) and Key On/Engine Running (KOER).
- Record all Diagnostic Trouble Codes (DTCs).
- Repair all non-transmission codes first.
- Repair all transmission codes second.
- Erase all continuous codes and attempt to repeat them.
- Repair all continuous codes which reappear.
- If only pass codes are obtained, proceed to Diagnosis by Symptom for further information and diagnosis. 4R100
Follow the diagnostic section to diagnose and repair the concern the first time.