Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSPONTIAC1983GRAND PRIX BASE, 5.0 HREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 11 (FEEDBACK CARBURETOR TESTS W/CODES)CODE 54: MIXTURE CONTROL (M/C) SOLENOID CKT HIGH
1983 Pontiac Grand Prix Base, 5.0 H
Code 54: Mixture Control (M/C) Solenoid CKT High
1983 Pontiac Grand Prix Base, 5.0 HSECTION Code 54: Mixture Control (M/C) Solenoid CKT High
WARNING: This page does not describe the selected car, but rather 28 other vehicles, including the 1984 Pontiac Phoenix, 1984 Pontiac Parisienne, 1984 Pontiac Grand Prix, 1984 Pontiac Firebird, and 1984 Pontiac Bonneville. However, it is still accessible from the selected car via links, so may be relevant.
Code 54 will be set if there is constant high voltage at ECM term. "18". A short circuit to 12 volts will cause M/C solenoid to remain in the full rich position.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- 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 18-32 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.
- This test checks if reason for high voltage to term. "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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.