Torque Converter Diagnosis

Torque Converter Diagnosis

Prior to 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 or remanufactured torque converter.
Begin with the normal diagnostic procedures as follows:
1. Preliminary Inspection
2. Know and Understand the Customers Concern
3. Verify the Concern - carry out the torque converter operation test.
4. Carry out Diagnostic Procedures:
^ Run on - board diagnostics.
- Repair all non - transmission related DTCs first.
- Repair all transmission DTCs.
- Rerun On - Board Diagnostic to verify repair.
- Carry out Line Pressure Test.
- Carry out Stall Speed Test.
- Carry out diagnostic routines.
- Use the index 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 repairing the torque converter.

Torque Converter Operation Test
This test verifies that the TCC control system and the torque converter are operating correctly.
1. Carry out Quick Test. Check for DTCs.
2. Connect a tachometer to the engine.
3. Bring the engine to normal operating temperature by driving the vehicle at highway speeds for approximately 15 minutes in (D) position.
4. After normal operating temperature is reached, maintain constant vehicle speed of about 80 km/h (50 mph) and tap the brake pedal with the left foot.
5. Engine rpm should increase when brake pedal is tapped, and decrease about five seconds after pedal is released. If this does not occur see torque converter operation concerns.
6. If the vehicle stalls in (D) or manual 2 at idle with vehicle at a stop, move the selector lever to manual 1 position. If the vehicle stalls see torque converter operation concerns. Repair as required. If the vehicle does not stall in (D), refer to Diagnosis By Symptom. [1][2]Diagnosis By Symptoms