P0742 = TCC stuck on. Symptom: engine stalls the moment you put it in drive. Cause: TCC apply valve stuck or solenoid stuck. Fix: replace solenoid AND apply valve together. 90 min job, pan off, no teardown.
Part You Need
4L80E TCC Solenoid + Apply Valve Kit
Step-by-Step
- 1Drain 4L80E fluid (~12-14 quarts Dexron VI). Heavier than a 4L60E, use a 6-gallon drain pan.
- 2Drop pan. Have HD pan jack if working solo - 4L80E pan is heavy with old fluid.
- 3Replace filter (PF1218 or equivalent) on reassembly.
- 4Locate TCC PWM solenoid - rear of valve body, single 2-pin connector.
- 5Remove TCC solenoid retaining bracket. Pull solenoid + apply valve as an assembly.
- 6Replace BOTH the solenoid AND the apply valve. Stock apply valve is the failure point as often as the solenoid itself.
- 7Lubricate o-rings on solenoid and apply valve.
- 8Install new apply valve into valve body bore. Install new solenoid. Reinstall retaining bracket.
- 9Reconnect TCC connector. Verify click-in.
- 10Install pan with new gasket. Torque pan bolts to 8 ft-lbs cross pattern.
- 11Refill with Dexron VI (~12 quarts to full).
- 12Clear codes. Test drive. Verify TCC engages and DISENGAGES properly when stopping.
If TCC stays applied after replacement, inspect for line pressure issue - failing pump could be holding apply pressure constantly. Pump test recommended.