Note On Intermittents

Manipulate ISC wiring while observing PCM input PI72 and while observing ISC operation during PCM output PO07. Manipulate TP sensor wiring and connector while observing PCM parameter PD01 for jumps, skips and/or intermittent behavior.

Ensure TP sensor is secured to throttle body (both screws tight). Cycle TP sensor through its full travel while observing parameter PD01 for erratic behavior. Check for proper TP sensor part number installed on vehicle. Unplug and reconnect TP sensor, ISC and PCM connectors, and ensure they are latched properly.

Fig 1: PCM Code P055 Schematic - TP Sensor Out Of Range

Courtesy of GENERAL MOTORS CORP.

Fig 2: PCM Code P055 Flow Chart - TP Sensor Out Of Range

Courtesy of GENERAL MOTORS CORP.