On any vehicle, the starter solenoid is an electromechanical device used to shift the starter motor pinion gear to mesh the engine flywheel. When a current is supplied to the solenoid ignition terminal, the windings inside become energized. This creates a magnetic field that pulls the internal plunger, moving the linkage to engage the starter. Easy, right? The solenoid plunger contact also closes the circuit between the starter motor and battery. The modern solenoid is attached directly to the starter motor. Typically, when the solenoid fails, the whole starter needs replacement. The next time your car won’t start, use this way to test a starter solenoid to find out if yours is shot.
Locate the Starter Solenoid
Gather some tools first, then locate the solenoid. You’ll need a jack, jack stands, jumper cables, and gloves. The starter of most vehicles is usually mounted to the bellhousing on the underside of the engine. You’ll need to first jack up the front of the car from a safe spot on the frame. Once it’s up, slide the jack stands in place underneath. You can leave the jack in place or lower it and let the car rest on the stands. If you’re not sure where the starter is, consult the owner’s guide or a repair manual. The starter is usually shaped like a cylinder, with another, smaller cylinder attached to it. A wire should extend from the positive terminal on the battery to the starter.
Checking the Starter Solenoid
The best way to test the starter solenoid is by connecting it to a test light. Find the two input and output terminals on the starter. Connect the tester to the output terminal—it will be the only one without a wire attached to it. Once you have activated the starter, it will internally connect both terminals. Hold the red lead on the test light, fixed on the upper terminal of the starter solenoid. Next, take the black lead on the test light and ground it to complete the circuit. Do this by touching it to any part of the vehicle that is bare metal. If the light tester comes on, then there is power running through the starter. This tells you that the battery is sending power, and the problem lies with the solenoid. If there is an electrical current running from the battery to the solenoid and the starter still isn’t working, the problem lies with the solenoid, and you will likely need to replace it.
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