Component Tests

Torque Converter Diagnosis
Prior to installing a new torque converter, all diagnostic procedures must be followed. This is to prevent the unnecessary replacement of good 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 Concern-Carry out the Torque Converter Clutch Operation Test.
4. Carry out Diagnostic Procedures.
- Run on-board diagnostics; see On-Board Diagnostics With NGS. Testing and Inspection
- Repair all non-transmission related DTCs first.
- Repair all transmission DTCs.
- Rerun on-board diagnostic to verify repair.
- Carry out the Line Pressure Test.
- Carry out the Stall Speed Test.
- Carry out the Diagnosis by Symptom Routine for torque converter diagnosis. 5R55N
- 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 service as necessary before servicing the torque converter.

Torque Converter Operation Test
This test verifies that the torque converter clutch control system and the torque converter are operating correctly.
1. Carry out the Quick Test; see On-Board Diagnostics With NGS. Check for DTCs. Refer to the Diagnostic Trouble Code Charts. Trouble Code to Pinpoint Test Charts
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 D5 position.
4. After normal operating temperature is reached, maintain a constant vehicle speed of about 80 km/h (50 mph) and tap brake pedal with the left foot.
5. The 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, Diagnosis By Symptom.
6. If the vehicle stalls in D5 or manual 2 at idle with vehicle at a stop, move the transmission range selector lever to manual 1 position. If the vehicle stalls, see Torque Converter Operation Concerns, Diagnosis By Symptom. Repair as necessary. If the vehicle does not stall in D5, refer to Diagnosis By Symptom.