How to Troubleshoot The Starter Circuit of a Truck

In this guide, you will learn how to troubleshoot the starter circuit of a truck. The starter system is simple, and troubleshooting is not complex. All you need are a few tools like the voltmeter, test lamp, tester, and a spanner to check the starter pinion is jammed in mesh with the engine flywheel. As you read this guide, you will understand how to troubleshoot the starter system of your truck.

How to Troubleshoot The Starter Circuit

If you would like to know how to troubleshoot the starter circuit of a vehicle, then the pointers below will help you through that.

Checking the Starter Pinion

You need to switch on your headlights and try the starter. If your headlight is dim, the starter is jammed in the mesh with the flywheel. Check if there is a square stub on the end of the starter-motor spindle. If you see it, use a spanner to turn it, and the pinion will be freed. 

Before you start working on the starter, ensure the pinion is freed. If you haven’t seen the square stub and your truck is a manual transmission, consider putting the gear level in the second gear with the ignition off, release your handbrake and rock your truck forward and back until you feel the pinion frees itself. For automatic transmission, you will have to take the motor off. When the headlights are still dim, consider checking for electrical faults.

Checking for Electrical Faults

When checking for electrical faults, consider checking the entire battery. Use a tester to confirm if the current reaches the solenoid.

Testing Power output

Connect the tester between the solenoid and the output terminal to check for the solenoid tester current. Connect one lead to the battery side of your solenoid and earth and the other to bare metal on the body of your truck. If the lamp lights, the solenoid, or the starter is the issue.

Sometimes the lamp may light when you earth it to the body, but not the engine of your truck, in such a case, the engine strap might be faulty. The connection between the solenoid and the battery might be defective if the lamp does not light.

Checking the Solenoid

You need a helper who will operate the starter switch as you listen to the solenoid to check if it is working. If your solenoid works, you will feel it producing a clicking sound. The ignition switch or its terminals might be faulty if it does not work.

To know if your solenoid is delivering power to the starter motor, consider connecting the test lamp between the output terminal and the earth, specifically the battery earth terminal. If your starter switch is working, you should be able to see the lamp lighting. 

Sometimes your lamp might fail to work. In such a scenario, put your truck in neutral gear, put off the ignition, and try to bridge the two terminals of the solenoid.

Checking the Battery

Connect the voltmeter on both the battery terminals and the readings should be 12 volts or more. As the voltmeter is connected, turn on the starter switch the voltage should drop to 10.5. If the voltage does not fall, there is a problem with the ignition switch or the solenoid.


Having gone through this guide, we now hope that you know how to troubleshoot the starter. If you are unsure what to do, consider getting some expert help from your mechanic.

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