Torque Converter Clutch Circuit Stuck On
The torque converter clutch is engaged continuously, causing engine load issues.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The torque converter clutch is supposed to engage and disengage when needed. If it's stuck on, it keeps the engine load high, which can cause stalling and overheating.
What the computer is actually seeing
The powertrain control module (PCM) monitors the torque converter clutch circuit voltage. If it sees a consistent high voltage (around 12V) with no change when it should disengage, it throws the P0742 code.
What a healthy reading looks like
Expected clutch engagement voltage is 0-0.5V when disengaged, and around 12V when engaged. PCM expects the voltage to drop below 1V during disengagement.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connectors to the torque converter clutch solenoid for damage, corrosion, or loose connections. Resolve any issues found. Decision Point: If wiring is damaged, repair it; if not, proceed to Step 2.
- 22. Measure voltage at the torque converter clutch solenoid connector with the engine running. You should see a swing in voltage from 0V to 12V. Decision Point: If voltage is correct, the solenoid is likely faulty; if not, proceed to Step 3.
- 33. Check the operation of the torque converter itself by monitoring engine RPM and vehicle speed. If the converter isn't locking or unlocking properly, it could be the converter issue. Decision Point: If the issue is with converter operation, replace it; if it behaves as expected, proceed to Step 4.
- 44. Scan for any other transmission-related codes. If other codes are present, address those issues as they may affect clutch operation. Decision Point: Fix any related codes before concluding diagnostics.
Common causes
- Faulty torque converter clutch solenoid
- Wiring or connector issues in the circuit
- Failing torque converter
- Faulty PCM software or hardware
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable, but you may experience performance issues and increased fuel consumption. Fix it soon.
Will this code come back after clearing?
If the underlying issue isn't fixed, yes, the code will likely return.
Can this code cause overheating?
Yes, if the torque converter clutch is stuck on, it can cause the engine to work harder and overheat.
Working a real vehicle right now?
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