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.

1. 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.
2. Checks for voltage supplied to brake switch.
3. Checks circuit No. 540 for short to ground.
4. Checks circuit No. 20 for short to ground.
5. Checks circuit No. 20 for open or for faulty PCM.

Fig 1: Code P106 Schematic, Stoplight Switch Input Circuit Problem

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code P106 Diagnostic Flow Chart, Stoplight Switch Input Circuit Problem

Courtesy of GENERAL MOTORS CORP.