How To Test The Starter Motor (GM 4.3L, 5.0L, 5.7L)

If you've been looking for a detailed step-by-step starter motor test, well you've found it. This article will show you how to test the starter motor on your GM 4.3L, 5.0L, or 5.7L pick up, van or mini-van.

Having your pick up (or van or mini-van) not start sucks, but having to diagnose and troubleshoot the problem doesn't have to.

To see if this starter motor test article covers your specific Cadillac, or Chevy or GMC or Olds or Isuzu vehicle, you can take a look at the list of applications on the box labeled ‘Applies To:’ and scroll with the prev and next links.

Before you jump into the tests, I recommend you read the entire article first. Also, you'll notice that the photos I'm using are of a starter off of the vehicle, this is just to make it easier to show you what you need to probe with your multimeter. The two tests in this article are On Car tests... so, don't remove the starter motor from your pick up (or van or mini-van).

Important Safety Precautions

Suggestion 1: The test explained in this tutorial is an On Car Test of the starter motor. Do not remove the starter motor from the vehicle to perform the test steps in this article. Although the photos I'm using show the starter motor off of the vehicle, this is just to make it easier to point out where you need to make your connections.

Suggestion 2: It's critical that you make sure your battery is fully charged before you start any of the tests in this tutorial. Also, the battery cable terminals and battery posts must be clean and corrosion free.

Suggestion 3: Use jack stands to keep your GM vehicle up in the air... don't trust the jack alone! 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.

STARTER TEST 1: Applying 12 V To The S Terminal

How To Test The Starter Motor (GM 4.3L, 5.0L, 5.7L)

The first we're gonna' do is manually apply 12 Volts to the starter motor with a remote starter switch.

This first test will either eliminate or condemn the starter motor as BAD right off the bat.

If you don't own a remote starter switch, you can run down to your local auto parts store (like AutoZone or O'Reilly Auto Parts) and buy one from there. If you need to see what one looks like, you can see it here: Actron CP7853 Remote Starter Switch for 6V and 12V Automotive Starting Systems

OK, this is what you'll need to do:

  1. 1

    As a safety precaution, disconnect the battery negative cable from the battery negative post, till you're done setting up the remote starter switch.

  2. 2

    Raise and place your vehicle on jack stands. The only way to gain access to the starter motor is from underneath your GM 4.3L, 5.0L, or 5.7L equipped pickup, van, mini-van or SUV.

  1. 3

    Disconnect the wire that attaches to the S terminal of the starter motor solenoid.

  2. 4

    Connect one end of the remote start switch to the S terminal on the starter motor solenoid and connect the other end to the battery positive post.

  3. 5

    Once you have everything set up, reconnect the battery negative cable terminal to the battery negative post.

    Apply 12 volts to the S terminal of the starter motor solenoid (using the remoter starter switch of course).

  4. 6

    As you apply these 12 Volts (to the S terminal of the starter solenoid), you'll get one of two results: The starter will activate and will turn over the engine or 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.

Also, since the starter motor did come alive and cranked the engine... This result lets you know beyond a shadow of a doubt that the starter motor is good and that you need to look at the ignition switch, or neutral safety switch as the cause of the No Start Condition on your car or mini-van. Go to: STARTER TEST 2: Verifying The Start Signal.

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 STARTER TEST 3: Voltage Drop Testing The Battery Cable.