Diagnostic Aids

Using the TECH-1 scan tester, select manual control function and exercise motor movement of affected channel in both directions while applying light pressure on the brake pedal. If erratic or jumpy brake pedal movement is detected while performing an apply or release function of the motor, an intermittent malfunction may be indicated.

Intermittent condition can be caused by a poor connection, rubbed through insulation or a wire that is broken inside the insulation. The frequency of the malfunction can be checked by using the enhanced diagnostic function of the TECH-1 scan tester as described in the tester manual.

Any circuitry that is suspected of causing an intermittent complaint should be thoroughly inspected for backed out terminals, improper mating, broken connector locks, improperly formed or damaged terminals, poor terminal-to-wire connections or physical damage to the wiring harness.

Fig 1: DTC A066 Schematic, Rear Motor Circuit Shorted To Battery

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC A066 Flow Chart, Rear Motor Circuit Shorted To Battery

Courtesy of GENERAL MOTORS CORP.