Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code 39, TCC Circuit (3.8L): Notes
Code 39 will set when TCC is commanded on, vehicle speed is greater than 35 MPH, throttle angle is greater than 10 percent, vehicle is in 3rd or 4th gear, Engine RPM-to-vehicle speed indicates TCC is not locked and all conditions have existed for more than 10 seconds. Code 39 does not turn on SERVICE ENGINE SOON light.
- With ALDL test terminal grounded, PCM provides a ground for solenoid. This step tests for power to solenoid.
- Tests to see if problem is faulty solenoid, power supply or driver circuit.
- Tests TCC solenoid driver circuit at PCM.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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