Code 66 - Pump Motor Relay Or Circuit Shorted: Notes

This code sets when VCM detects high voltage at Black VCM connector terminal "A" (4.3L VIN Z M/T) or Gray VCM connector terminal "C" (except 4.3L VIN Z M/T) when ABS pump motor relay is not supposed to be on. VCM monitors feedback voltage on circuit 173 and sets Code 66 if voltage is not supposed to be present.

Fig 1: Code 66 - Schematic (4.3L M/T - VIN Z)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 66 - Schematic (Except 4.3L M/T - VIN Z)

Courtesy of GENERAL MOTORS CORP.

Fig 3: Code 66 - Pump Motor Relay/Circuit Shorted - Flow Chart

Courtesy of GENERAL MOTORS CORP.