Torque Converter Diagnosis

Torque Converter Diagnosis
Prior to torque converter replacement, all diagnostic procedures must be followed. This prevents the unnecessary replacement of good torque converters. Only after a complete diagnostic evaluation can the decision be made to replace the torque converter.
Begin with the normal diagnostic procedures as follows:
1. Preliminary Inspection.
2. Know and understand the customer's concern.
3. Perform the Torque Converter Operation Test. See AUTOMATIC TRANSMISSION PRELIMINARY INSPECTION. Automatic Transmission Preliminary Inspection
4. Perform diagnostic procedures.
^ Perform on-board diagnostics with WDS or equivalent tester. See AUTOMATIC TRANSMISSION DIAGNOSIS. Reading and Clearing Diagnostic Trouble Codes
^ Repair all non-transmission related DTCs first.
^ Repair all transmission DTCs.
^ Rerun on-board diagnostic to verify repair.
^ Perform Line Pressure Test. See Line Pressure Test. Line Pressure Tests
^ Perform Stall Speed Test. See Stall Speed Test. Stall Speed Test
^ Perform Diagnosis by Symptom Procedure. See SYMPTOM TROUBLESHOOTING CHART-AUTOMATIC TRANSMISSION. Symptom Troubleshooting Chart-Automatic Transmission

Torque Converter Operation Test
This test verifies that the torque converter clutch control system and the torque converter are operating properly.
1. Perform Quick Test.
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 (Overdrive) 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.
^ Engine rpm should increase when brake pedal is tapped, and decrease about five seconds after pedal is released.
^ If this does not occur, see SYMPTOM TROUBLESHOOTING CHART-AUTOMATIC TRANSMISSION Torque Converter Operation Concerns. Symptom Troubleshooting Chart-Automatic Transmission
5. If the vehicle stalls in D (Overdrive) 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 SYMPTOM TROUBLESHOOTING CHART-AUTOMATIC TRANSMISSION Torque Converter Operation Concerns. Repairs required. Symptom Troubleshooting Chart-Automatic Transmission
^ If the vehicle does not stall in D (Overdrive), see SYMPTOM TROUBLESHOOTING CHART-AUTOMATIC TRANSMISSION. Symptom Troubleshooting Chart-Automatic Transmission