Testing to see if the starter motor is the one causing your GM 3.1L or 3.4L equipped car or mini-can not to crank and start is an easy test to perform. In this article I'll show you how to do it in three simple test steps. Since this is an On-Car Test of the starter motor, you don't even have to remove it from the car or mini-van.
To see if this starter motor test article covers your specific Chevrolet or Buick or Olds or Pontiac vehicle, you can take a look at the list of applications on the box labeled ‘Applies To:’ on the column on the right and scroll with the prev arrow and next arrow links.
Here are the contents of this article at a quick glance:
- Important Safety Precautions.
- STARTER TEST 1: Applying 12 V to the Starter Motor S Terminal
- STARTER TEST 2: Verifying the Start Signal from The Ignition Switch
- STARTER TEST 3: Voltage Drop Testing the Battery Cable
- Symptoms of a BAD Starter Motor.
- Related Test Articles.
You can find this tutorial in Spanish here: Cómo Probar el Motor de Arranque (GM 3.1L, 3.4L) (at: autotecnico-online.com).
Important Safety Precautions
Suggestion 1: The photos I'm using show the starter motor off of the car (or mini-van) only to facilitate the explanation of the test. Do not remove the starter motor from the vehicle to perform the test steps in this article.
Suggestion 2: It's super important that you do have a fully charged battery before you do TEST 1 and TEST 2 of this tutorial... or you'll end up with a false test result that'll have you replacing good parts. Also, the battery cable terminals must be clean and corrosion free.
Suggestion 3: You may need to perform some of these tests while you're underneath the vehicle. This means that you'll need to jack up the front of the car or mini-van. Take all necessary safety precautions, like using jack stands to hold up the vehicle, wearing eye-protection (safety glasses), etc.
Suggestion 4: Remove the key from the ignition switch. This will prevent the engine from starting... in case the starter motor is OK.
Suggestion 5: If you're vehicle has a standard transmission... make sure that it's out of gear and in neutral, and the parking brake is activated/on.
Suggestion 6: There's a good chance that the starter motor is OK and when you apply these 12 Volts with the jumper wire, the engine may start if you have the key rotated to run (on the ignition switch)... so be careful, take all necessary safety precautions and think safety as you do this test.
STARTER TEST 1: Applying 12 Volts to the Starter Motor S Terminal
The very first you'll need to do is to apply 12 Volts to the S terminal of the starter motor solenoid, using a jumper wire (or a remote start switch) to see if the starter will activate or not.
This is a very simple test that will tell right away if the starter motor is OK and the problem lies elsewhere or if you need to go to TEST 2. If you haven't read the section above (Important Safety Precautions), please do before you start your tests.
OK, this is what you'll need to do:
Disconnect the wire that attaches to the S terminal of the starter motor starter motor.
Using a jumper wire that's long enough (or a remote start switch)... apply 12 volts to the S terminal of the starter motor starter motor.
As you apply these 12 Volts (to the S terminal of the starter starter motor), you'll get one of two results:
- The starter will activate and will turn over the engine
- The starter motor won't do a thing.
Let's take a look at what your test results mean:
CASE 1: The starter motor cranked the engine. This means that the starter motor is good and that you have an electrical issue keeping the starter motor from cranking the engine.
The next step is to go to TEST 2 and see if the starter motor starter motor is getting the Start Signal on the S terminal wire (circuit). Go to TEST 2: Verifying the Start signal from the ignition switch.
CASE 2: The starter motor DID NOT crank the engine. This usually means that your starter motor is BAD and needs to be rebuilt or replaced.
I suggest one more test and this is to test the battery cable (that attaches to the starter motor starter motor) for corrosion. This can be accomplished very easily with a voltage drop test. Go to TEST 3: Voltage Drop Testing the Battery Cable.