Ford 2003 Mustang Workshop Manual page 2301

SECTION 307-01: Automatic Transaxle/Transmission
DIAGNOSIS AND TESTING
Diagnostic Strategy
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.
NOTE: Do not take any short cuts or assume that critical checks or adjustments have already been
made.
Follow the procedures as written to avoid missing critical components or steps.
To properly diagnose a concern have the following publications available:
Transmission Reference Manual.
Powertrain Control/Emissions Diagnosis (PC/ED) manual.
TSBs and OASIS Messages.
Wiring Diagram.
These publications provide the information required when diagnosing transmission concerns.
Use the Diagnostic Flow Chart as a guide and follow the steps as indicated.
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 proper adjustment.
Check TSBs and OASIS messages regarding 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.
If only pass codes are obtained, refer to
diagnosis.
Follow the diagnostic sequence to diagnose and repair the concern the first time.
2003 Mustang Workshop Manual
Diagnosis By Symptom for further information and