Code 54: M/C Solenoid Circuit High

Code 54 will be set if there is constant high voltage at ECM terminal "18." A short circuit to 12 volts will cause M/C solenoid to remain in the full rich position, resulting in potential ECM damage, excessive fuel consumption and excessive exhaust order.

1. This test checks the M/C solenoid resistance to determine if the fault is in the solenoid or ECM harness/ECM. Normal reading for a solenoid is 20-32 ohms.
   NOTE: After replacing a faulty M/C solenoid, a system performance test is necessary to be certain the M/C solenoid was the only faulty part. Solenoid may have caused the ECM to fail. This will reset code.
2. This test checks if reason for high voltage to terminal "18" is a faulty ECM or a short to 12 volts on that wire. If the test light to ground lights at the M/C solenoid test lead with both ends of harness disconnected, there is a short to 12 volts in the wire.

Fig 1: Code 54: M/C Solenoid Circuit High