Diagnostic Aids

An intermittent condition may be caused by a poor connection, rubbed-through wire insulation, or a broken wire inside insulation. Check ECM/PCM harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness.

Fig 1: Chart C-1A Schematic - Electrical Load Idle-Up Diode Circuit Check

Courtesy of GENERAL MOTORS CORP.

Fig 2: Chart C-1A Flow Chart - Electrical Load Idle-Up Diode Circuit Check

Courtesy of GENERAL MOTORS CORP.