How to Troubleshoot a Motor Starter

The circuit for the starter starts at the battery. The battery has a large positive wire that goes directly to the solenoid on the starter. To activate the solenoid, the power goes from the battery through a separate line to the fuse box to a distribution bar. From this bar, the power goes to the fuse for the starter and then to the starter relay. The opposite terminal has a small 16-gauge wire running to the solenoid on the starter and is used to activate the starter when energized. To activate the relay and energize the solenoid, the power comes from the ignition switch yellow wire to the security system if any, down to the neutral safety switch (or clutch switch if a manual transmission), then to the relay.
When the switch is turned to the start, the power runs through these circuits described and to the relay, activating it and then to ground. There must be power from the switch, through the circuits to the relay. The relay must have a good ground to activate. There must be power from the fuse to the opposite side of the relay, which is the side that will send power to the solenoid through the small wire, and the relay must operate.

Difficulty: Moderate

Instructions

Things You'll Need:

• Voltmeter

1. Check for 12 volts on the large wire attached to the top terminal on the starter relay. It should have battery voltage. If not, the battery, terminals or wire is bad.

2. Check the small wire on the solenoid for power when the key is in the start position. Remove the small wire on the solenoid and have a helper hold the key in the start position. Check the wire for battery voltage. If there is voltage, the starter is bad. If there is no voltage, replace the wire.

3. Check the fuse in the fuse box under the hood on the left fender well. If it is good, check the relay by pulling it out and checking for power at one terminal with the key off. If there is no power, the problem is in the fuse box between the fuse and the relay. If there is power, have the helper hold the key in the start position once again and check for power at another terminal from the ignition key. If there is power, the relay is bad. If there is no power, the starter circuit is suspect.

4. Check to see if there is power to the neutral safety switch if there is no power at the relay. Use the voltmeter to check for power with the key in start. If there is power going in, check for power going out. If there is no power going in, the security system or ignition switch is suspect. If there is power going in and none coming out, the switch is bad. If there is power coming out, the problem is between the neutral switch and the relay.

5. Remove the cover on the bottom of the steering column. Check the solid yellow wire for power when the key is in the start position. If there is no power, the ignition switch is bad.

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