Ford Mustang (1999-2004) Service Manual: 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 By Symptom for further information and diagnosis.

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

Diagnostic Flow Chart

Diagnostic Flow Chart
  • Know and understand the customer concerns
  • Check the fluid level and condition
  • Verify the concern by operating the vehicle
  • Check for non-factoryinstalled items and verify correct installation
  • Check the shift linkage adjustments
  • Check TSBs and OASIS messages for vehicle concerns
  • Carry out quick test both KOER and KOEO
  • Record all codes

1) Did you record any diagnostic trouble codes?

 Yes  REPAIR all hard diagnostic trouble codes. FOLLOW the pinpoint tests. REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual first, then this Workshop Manual.
  No  REFER to Diagnosis By Symptom in this section, then GO to Step 5.
2) Are any continuous test memory codes present? Yes  CLEAR codes and CARRY OUT drive cycle test.
  No  GO to Step 4.
3) Did the continuous test memory codes reappear? Yes  REPAIR all continuous test memory codes. FOLLOW the pinpoint tests. REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual then the transmission reference manual, then this workshop manual, then GO to Step 4.
  No  GO to Step 4.
4) Is the concern repaired? Yes  CARRY OUT the final quick test to verify that no diagnostic trouble codes are present. CLEAR memory codes.
  No  REFER to Diagnosis By Symptom in this section.
5) Are there any electrical concerns? Yes  INSTALL the scan tool and CARRY OUT the output state control test, then GO to Step 6.
  No  REFER to the hydraulic and mechanical routine to diagnose and REPAIR the concern, then GO to Step 7.
6) Was the transmission concern corrected when the scan tool was installed? Yes  REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual, intermittent fault diagnosis section and use the scan tool to diagnose cause of concern in the processor, vehicle harness or external inputs (sensors or switches).
  No  REFER to the hydraulic and mechanical routine to diagnose the concern, then GO to Step 7.
7) Is the concern repaired? Yes  CARRY OUT the final quick test to verify that no diagnostic trouble codes are present. CLEAR memory codes.
  No  Get assistance from technical hotline.
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