Diagnosing a bad Starter

No matter what the vehicle model, it is important to understand how the starter gets power, so that you can properly diagnose why the vehicle is not starting. The easiest ways to find out how the starter receives its power is to google the wiring diagram for your starter. The other ways of receiving a wiring diagram is websites like Alldata, and the manufacturer website.

Before doing any checks on the vehicle wiring, you should run a couple easy test to make sure that it is a issues with the starter. Turn the key on, does the dash lights come on? If not, then check that you have 12 volts on your battery and that all battery connections are tight and clean. If the lights come on, then try to start the vehicle. Does the vehicle do anything? If the vehicle cranks but does not start, then the starter is working and the vehicle is having another issue. If the starter clicks, but does not start the vehicle then we know there is a good chance that the starter wiring is working properly but the starter is not fully engaging (this could be caused from a bad starter, bad ground, other issues).

If the starter clicks when trying to start the vehicle but does not turn over the vehicle then it could be a couple of causes. The first thing to test to make sure you are getting 12 volts on the signal wire (usually a single wire, yellow in color) hooked to the starter solenoid. If you have 12 volts on the wire when trying to start the vehicle, then you can have one person try to start the vehicle and another person hit the starter solenoid with a hammer at the same time. If the vehicle will now start, then we know that the starter solenoid is bad, and the starter will need to be replaced.

*You can also use a test light on the starter signal wire to see if you have power.

If the starter does not click, then you will still need to see if you have power on the signal wire. If you have power but the starter is not engaging, there is a good chance that the starter is bad. If there is not power when trying to start the vehicle on the starter signal wire, then you will need to check where the power comes from. It usually starts on the ignition switch, moves to the starter relay and then to the starter. If the vehicle is not in park/neutral, then the vehicle will not send power to the starter signal wire. If the the brake lights are not working (brake pedal switch) then the vehicle will also not send power to the starter signal wire. It is important to make sure your vehicle is in park, and that the brake lights are working before performing any heavy diagnosing of the starter circuit.

If you have no power at the start signal wire, but the vehicle is in park and the brake lights are working, then you will need to check for power at the starter relay when you try to start the vehicle. If you have power at the relay, but not at the starter. Then either the relay is bad, or the wiring from the relay to the starter is bad. If you do not have power at the starter relay when trying to crank the vehicle, then either the ignition switch is bad, or the wiring from the ignition switch to the starter relay is bad.

In conclusion, most starter issues end up being a bad starter but it is important to understand how the starter on your vehicle gets its power. This way you can properly diagnose why the vehicle is not starting. If you have any questions on why your vehicle is not starting feel free to message me and I can help you with the steps to diagnosing the issue.

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