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 Switch (TCS)
The TCS is a momentary contact switch that sends a signal to the PCM when the driver selects the D4 position, canceling operation of 5TH (overdrive) gear.
The TCS is located within the range selector assembly for the base shifter only.
The PCM uses this signal to control the shift solenoids to disengage/disable 5TH gear operation and activates coast clutch for the base shifter only. At the same time the PCM changes the instrument panel indicator to display D4.
When the driver moves the selector lever back to the D5 position, 5TH gear operation is enabled, the coast clutch is released and the instrument panel indicator displays D5.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no 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.