How to Bench Test
a Starter Motor (Step by Step)
-Part I-
a Starter Motor (Step by Step)
-Part I-
Bench Testing the Starter is the most effective way to find out if the Starter Motor is in fact BAD. This is an easy test that you can accomplish yourself without having to take the Starter Motor to AutoZone or O’reilly or Pepboys Auto Parts.
This is an OFF Car test. So you'll need to remove the Starter Motor from the car or truck to bench test it.
It's a very easy test to do. The hardest part is removing the Starter Motor. Below you're gonna' find some useful and important tips that'll make this test a breeze.
Common Symptoms of a BAD Starter
Before we start you may want to know what are some of the most common symptoms of a BAD Starter:
- You turn the key to Start and nothing happens. The engine won't crank.
- Or you turn to key to Start and all you hear is just one loud click.
- The battery is good. You know that because:
- You have already replaced it with a new one.
- or you have tried to jump-start it.
Guidelines for Bench-Testing Starter
I have seen so many folks have trouble with this very simple test. By following these simple guidelines you'll be able to correctly diagnose a BAD Starter.
- You'll need some Battery Jumper Cables.
- A Jumper Wire.
- The most important thing will be that you'll need a working Battery.
- It can NOT be a new Battery.
- This Battery should come from a working vehicle if possible.
- You CAN NOT use a Jump Box instead of an actual battery.
- You need to place the Starter in a vise if you have one.
- If no vice is available, you'll need to have a helper hold it while you do the test.
- All safety precautions must be taken to not get fingers or anything else caught in the spinning Pinion Gear.
Following these simple guidelines will save you a headache and or having to replace a good starter.
Bench Testing the Starter: A Step by Step Test
Whether your car or truck is a Ford, a Chevrolet, a Nissan, a Mazda, a Dodge, a Chrysler, a Toyota or whatever... This Starter Bench Test applies.
If you have already read the important tips on Bench Testing the Starter, we can now start. The photo of the starter motor used in this article is a generic one for ease of explaining the tests. The Starter Motor on your vehicle will look similar.
STEP 1: The Circuit Descriptions
To Bench Test the Starter you'll need battery jumper cables, a jumper wire, a working battery, and of course the Starter Motor out of the car or truck. These are the circuit descriptions of the photo above:
- number 1: This is where the Start/Crank wire is attached to. When you turn the Ignition Switch to Start/Crank this wire delivers 12 Volts to activate the Starter Solenoid. This in turn makes the Starter Motor work.
- number 2: This is where the Cable from the Battery is attached to.
- number 3: The Grounding point. The Starter Motor is grounded thru' its case.
Attaching the Power and Ground Circuits
Attach one Jumper Cable to the Battery Negative Terminal. Attach the other end of that same Cable to the Starter Motor Case as shown on the photo above.
Attach the remaining Jumper Cable to the Battery Positive Terminal. Attach the other end of this same Cable to the stud on the Starter Motor Solenoid to which the Battery Cable is attached to as shown on the photo above.
STEP 3: Using a Jumper Wire
Attach one end of the Jumper wire to the Jumper Cable that you have just connected to the Starter Solenoid.
If you don't have the Starter Motor in a vise, have someone or something hold it firmly (watch-out for the spinning pinion gear!). When you're ready, with the other end of the Jumper Wire you're gonna' touch the Starter Solenoid Terminal to which the Start/Crank Wire is attached to.
So, once you have everything set up, touch the Starter Solenoid Start/Crank terminal with the Jumper Wire and observe/hear the results.
Interpreting the Results
You're only gonna' get one of three results from Bench Testing the Starter Motor. They pretty much boil down to: Either the Starter Motor will come out to play or not. More specifically:
- The Starter Motor will work and the Starter Motor Pinion Gear will come out and spin fast and freely. If this happens, the Starter Motor is good.
- The Starter Motor Pinion Gear will come out and spin very but very slowly. If this happens, the Starter Motor is BAD.
- Or you're only gonna' hear a loud click, and nothing more. This result lets you know that the Starter Motor is BAD.
