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: Notes
Code 39 will set when TCC is commanded by PCM/TCM, transmission is in high gear, engine speed-to-vehicle speed ratio does not indicate TCC has engaged and 2nd or 3rd gear is indicated. All these conditions must be met for more than 2 seconds.
- This step tests for poor connection at transmission pass-through connector.
- This step tests for power to transmission pass-through connector.
- This step tests for PCM/TCM control of TCC.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.