Note On Intermittents

Code P027 may set if TCC brake switch is sticking open or if accelerator and brake pedals are depressed simultaneously. Refer to input test PI71 to verify proper switch function.

Fig 1: Code P027 Schematic, Open Throttle Position Switch Signal

Courtesy of GENERAL MOTORS CORP

Fig 2: Code P027 Diagnostic Flow Chart, Open Throttle Position Switch Signal

Courtesy of GENERAL MOTORS CORP