Code 53, Ground CKT Open (CALIF. Only)

On California vehicles, an additional ground is supplied to ECM. ECM supplies 5 volts to Black/Green wire through a buffer. ECM expects voltage to be low. This code is set if voltage is high for 3 seconds.

1. This verifies Code 53 is not intermittent.
2. With test light to battery positive, probing Black/Green wire checks for open circuit in wire to engine block.

Fig 1: Code 53 Flow Chart, Ground Ckt. Open (Calif. Only)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 53 Schematic, Ground Ckt. Open (Calif. Only)

Courtesy of GENERAL MOTORS CORP.