P0742

P0742-TORQUE CONVERTER CLUTCH CIRCUIT STUCK ON





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

This Diagnostic Trouble Code (DTC) checks the mechanical operation of the Torque Converter Clutch (TCC). When the TCC is commanded on, there should be little or no difference between Engine speed and Input speed. If the TCM detects an engine stall, (engine rpm less than 100 rpm), and no slip in the TCC, the DTC is set and the TCM will disable the TCC and default into engine stall avoidance control.

- When Monitored:
No other DTCs set.

Engine rpm greater than 400 rpm

- Set Condition:
Engine speed drops below 100 rpm with no TCC slip detected.





Always perform the AW60T Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

1. CHECK IF DTC IS CURRENT
1. Using the scan tool, read TCM DTCs.
2. Record the Environmental Data and any DTCs.
3. Clear DTCs.
4. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
5. Read TCM DTCs.

NOTE: If there are any other Engine and/or Transmission DTCs, diagnosis those first.

Did the DTC reset?

Yes

- Go To 2

No

- Go To 6

2. CHECK THE TORQUE CONVERTER CLUTCH (TCC) OPERATION
1. Clear Transmission DTCs.
2. Road test the vehicle in a condition that will enable TCC lock up.
3. Idle vehicle in Drive.
4. Using the scan tool, note Torque Converter State.
5. Using the scan tool, record engine rpm and input rpm and calculate the TCC slip rpm.

NOTE: TCC slip rpm is the difference between engine rpm and input speed rpm.

Is the TCC slip rpm less than 100 rpm, with TCC commanded off?

Yes

- Go To 3

No

- Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the TCM. AW60T TCM Programming Procedure.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

3. CHECK THE L-UP LINEAR SOLENOID




1. Turn the ignition off to the lock position.
2. Disconnect TCM harness connector and remove the TCM from the transmission.
3. Measure the resistance of the L-Up Linear Solenoid between the appropriate terminals of the TCM transmission connector.

Is the resistance 6.0 Ohms (± 0.20 of an Ohm)?

Yes

- Go To 4

No

- Replace the L-Up Linear Solenoid. Service and Repair.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

4. CHECK THE L-UP LINEAR SOLENOID FOR A SHORT TO GROUND




1. Measure the resistance of the L-Up Linear Solenoid between ground the appropriate terminals of the TCM transmission connector.

Is the resistance below 100k Ohms?

Yes

- Remove the Transmission Side cover and inspect the internal harness for short to ground. If no short is found, replace the L-Up Linear Solenoid. Service and Repair.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

No

- Go To 5

5. CHECK INTERNAL TRANSMISSION
1. Turn the ignition off to the lock position.
2. Remove the Transmission Side cover.
3. Check the internal transmission harness, pins, terminals, and connectors for shorts, corrosion, damage, or terminal push out.
4. Visually inspect the valve body for debris, damage or leaking hydraulic paths.
5. Visually inspect for sticking or binding Control Valve(s).

Were there any problems found?

Yes

- Repair as necessary.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

No

- Replace the Torque Converter.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

6. CHECK WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorted and open circuits.
4. Check for any Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the AW60T VERIFICATION TEST. AW60T Transmission Verification Test.

No

- Test Complete.