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.
Transmission Control (TC) Switch and Transmission Control Indicator Lamp (TCIL)
The transmission control (TC) switch and transmission control indicator lamp (TCIL) are located inside the end of the selector lever. For vehicles equipped with a 4R70E/4R75E and a Torqshift® with a diesel engine, pushing the TC switch will either disengage or engage the overdrive function of the transmission. When overdrive is disengaged, the TCIL will illuminate the word OFF. Each time the ignition switch is placed in the RUN position, the transmission will automatically provide overdrive operation regardless of TC switch position the last time the vehicle was running.
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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.