Note On Intermittents

Ensure ISC plunger is depressed when throttle linkage contacts stop screw. Check ISC jumper connectors and PCM connector for loose or improperly crimped terminals.

Fig 1: PCM Code P027 Schematic - Open Throttle Switch Signal

Courtesy of GENERAL MOTORS CORP.

Fig 2: PCM Code P027 Flow Chart - Open Throttle Switch Signal

Courtesy of GENERAL MOTORS CORP.