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 P106, Stoplight Switch Input Circuit Problem: Action
Traction control disabled. PCM will set stop/BTSI/cruise brake switch status not applied. TRACTION DISABLED and REDUCED ENGINE POWER message displayed.
- Checks if PCM input test PI89 will cycle when brake pedal is depressed and released. If PI89 remains HI, check for short to voltage in system. If P189 remains LO, check for open or short to ground in system.
- Checks for voltage supplied to brake switch.
- Checks circuit No. 540 for short to ground.
- Checks circuit No. 20 for short to ground.
- Checks circuit No. 20 for open or for faulty PCM.
Use the Manual With the Right Hardware
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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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