Ford Solenoid Troubleshooting

by Lauren Treadwell

Solenoids are a critical component of the ignition process in automobiles. Also known as starter relays, solenoid starters jumpstart the motor with electric current from the battery when the ignition key is turned. Ford solenoids are among the most popular starters in the automobile industry since they are connected directly to the battery, giving ample power when starting the vehicle. Unfortunately, like all car parts, Ford solenoids are still prone to malfunctions that can keep an otherwise roadworthy car stuck in the driveway.

Diagnosing the Problem

The solenoid is connected to the Ford's battery and electrical devices, including the ignition. If there is a problem with any of the car's electrical components, the solenoid could be to blame. The most common solenoid problem in a Ford is restarting the car while the engine is still hot. If the car easily restarts when the engine is cooled for 30 minutes, it likely means that the solenoid is overheating. Another telltale sign that a Ford solenoid is acting up is when turning the ignition key does not start the engine and the interior lights don't flicker or turn off.


Ask a friend to start your Ford's engine by turning the ignition. With the hood open, watch the starter (located near the battery). If it does not spin, there are two possible problems. It could be that the power running to the starter solenoid is insufficient, or it could mean that the power is reaching the solenoid but not arriving at the motor. The easiest way to determine the problem is to turn on the Ford's interior lights and start the car again. If the starter doesn't spin and the lights don't dim, the solenoid isn't getting enough power. You'll need to replace either the ignition switch, the starter relay, the transmission safety switch, the solenoid itself or the wiring connecting them. If the lights dim during this test, you'll need to inspect the battery cables and the battery itself.

Replacing the Solenoid

Once you've isolated the solenoid as the root of your car trouble, you'll need to replace it. Replacing a Ford's defective solenoid requires access to the battery, ignition and transmission. Before starting, consult your Ford's service manual or purchase a Chilton replacement. This will act as the roadmap to your engine components to make sure you don't disconnect the wrong wires. Disconnect the battery terminals and proceed to remove the old solenoid starter. Once it is removed, you will need to mount and attach the new solenoid using cables that fit properly. Test the solenoid by turning your ignition with the interior lights on. If the Ford starts and the lights do not dim or turn off, take the car for a significant ride. Once the car's engine is hot, return to your driveway and turn it off completely. The engine should restart immediately without a problem.

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