Torque Converter Diagnosis

4R70E/4R75E

Torque Converter Diagnosis





WARNING: If equipped with fire suppression system, refer to Fire Suppression System for Important Safety Warnings. Failure to follow this instruction may result in serious personal injury Procedures.

Prior to new torque converter installation, all diagnostic procedures must be followed. This is to prevent the unnecessary installation of new or remanufactured torque converters. Only after a complete diagnostic evaluation can the decision be made to install a new torque converter.

Begin with the normal diagnostic procedures as follows:

1. Preliminary inspection.

2. Know and understand the customer concern.

3. Verify the condition - carry out the Torque Converter Operation Test. Torque Converter Operation Test

4. Carry out diagnostic procedures.

- Carry out On-Board Diagnostic (OBD); refer to Diagnostics Diagnostics.
- Repair all non-transmission related DTCs first.
- Repair all transmission DTCs.
- Rerun OBD to verify repair.

- Carry out Line Pressure Test. Refer to Special Testing Procedures. Line Pressure Test Special Testing Procedures
- Carry out Stall Speed Test. Refer to Special Testing Procedures. Stall Speed Test Special Testing Procedures
- Carry out Diagnostic Routines. Refer to Diagnosis By Symptom. Diagnostic Routines Diagnosis By Symptom
- Use the Diagnosis by Symptom Chart to locate the appropriate routine that best describes the symptom(s). The routine will list all possible components that may cause or contribute to the symptom. Check each component listed; diagnose and repair as required before changing the torque converter.