How to Clean a Starter Relay

When you turn a vehicles key switch to the "Start" position it is actually turning on the starter relay, not the starter itself. The starter relay receives a signal from the key switch that routes battery voltage to the starter solenoid. The current draw on the starter solenoid is so high that this intermediate component is placed in between the key switch and the starter to save the components and wires from failing. Excessive moisture can cause the relay terminals to corrode. Disconnecting the starter relay and cleaning the corrosion from the contacts can help prevent problems down the road.

Instructions

1

Use a 10mm wrench to disconnect the negative battery cable. Place the cable beside the battery so it will not accidentally contact the battery posts. Use a 10mm wrench to disconnect the positive battery cable. Place the cable beside the battery so that it will not accidentally contact the battery posts.

2

Follow the wires from the starter solenoid to the starter relay. The starter relay has four wires connected to it. The two smaller wires are from the key switch. These wires turn the relay "On" so that voltage can pass through the starter relay to the starter solenoid. The larger wires route battery voltage from the battery to the starter solenoid.

3

Inspect the wires on the starter relay. The terminals should be free of corrosion, oil and dirt. Use an adjustable wrench to remove the nuts from the terminal posts. Remove the wire and connector. If you find corrosion on the terminals, sprinkle baking soda on the corrosion, dip a wire brush in water and scrub the corrosion from the terminal. Replace the terminal on the stud. Use the adjustable wrench to tighten the nuts on the terminal posts.

4

Place the positive battery cable on the positive battery post. Use a 10mm wrench to tighten the clamp on the battery post. Place the negative battery cable on the negative battery terminal, and use a 10mm wrench to tighten the clamp on the battery post.