How To Test The Starter Motor (1988-1993 2.8L V6 Chevrolet S10 Pickup, GMC S15 Pickup)

How To Test The Starter Motor (1988, 1989, 1990, 1991, 1992, 1993 2.8L V6 Chevrolet S10 Pickup, GMC S15 Pickup, And GMC Sonoma)

I think you'll be surprised at how easy it is to troubleshoot the starter motor to determine if it's good or bad.

In this tutorial, I'll explain the three tests you need to do on the starter to determine if it's good or bad. All three tests are performed without removing the starter motor from the vehicle.

NOTE: The starter motor test in this tutorial is an on-car test. The photos I'm using show the starter motor off of the vehicle only to explain the test connections better.

APPLIES TO: This tutorial applies to the following vehicles:

  • 2.8L Chevrolet S10 Pickup: 1988, 1989, 1990, 1991, 1992, 1993.
  • 2.8L GMC S15 Pickup: 1988, 1989, 1990.
  • 2.8L GMC Sonoma: 1991, 1992, 1993.

Important Testing Tips

TIP 1: Ensure the battery has a full charge before starting any of the tests in this tutorial.

TIP 2: The battery cable terminals and the battery posts should be clean and corrosion-free before starting the tests.

TIP 3: Read the entire article first to familiarize yourself with the tests.

TIP 4: Use jack stands for safety. Don't trust the jack alone to keep your vehicle up in the air while you're underneath it!

TIP 5: Take all necessary safety precautions. Use safety glasses while working underneath the vehicle. Be alert and think safety all of the time.

Symptoms Of A Bad Starter Motor

A starter motor that is malfunctioning will cause one of two problems:

  • An engine no-crank problem that won't be resolved until the starter is replaced.
  • An intermittent engine no-crank problem. In other words, the starter works properly most of the time, but sometimes it doesn't.

NOTE: It's important to remember that if your vehicle has an intermittent engine no-crank issue, the starter motor will need to be checked or tested when the no-cranking issue occurs.

Tools Needed To Test The Starter Motor

No expensive diagnostic equipment is required to test the starter motor. Here's a list of the things you'll need:

TEST 1: Applying 12 Volts To The S Terminal

Applying 12 Volts To The S Terminal. How To Test The Starter Motor (1988, 1989, 1990, 1991, 1992, 1993 2.8L V6 Chevrolet S10 Pickup, GMC S15 Pickup, And GMC Sonoma)

The starter motor receives a 12 Volts activation signal when you turn the key to crank and start the engine.

This 12 Volts enable signal is provided to the starter motor solenoid S terminal.

In this second test section, we'll apply 12 Volts directly to the starter solenoid S terminal.

The purpose of this test is to bypass the 12 Volts enable signal from the ignition switch and see if the starter motor will activate and crank the engine.

I recommend that you use a remote start switch to easily and safely apply 12 Volts to the S terminal of the starter motor solenoid. You can purchase or rent this tool at your local AutoZone or O'Reilly Auto Parts store.

You can see an example of a remote start switch and where to buy it here:

IMPORTANT: Remove the key from the ignition switch for this test. If your Chevy S10 (GMC Sonoma) is equipped with a standard transmission, place it in neutral.

OK, let's get testing:

  1. 1

    Raise the front of your vehicle and place it on it's jack stands (to gain access to the starter motor).

  2. 2

    Disconnect the battery negative (-) terminal.

    You'll reconnect it back in one of the following steps; for now, it's a safety precaution as you set up the test.

  3. 3

    Attach one end of the remote starter switch to the battery positive (+) post.

  4. 4

    Attach the other end of the remote starter switch to the S terminal of the starter motor solenoid.

    This is easier said than done, so take your time and make sure the connection is on the S terminal of the starter motor solenoid.

    Also, in case you're wondering, you can leave the starter motor solenoid's S terminal wire connected to the engine's wiring harness connector or not, the test will work either way.

  5. 5

    Reconnect the battery negative (-) cable to the battery negative post.

  6. 6

    Apply 12 Volts to the S terminal wire of the starter motor starter solenoid with your remote starter switch.

  7. 7

    You'll get one of two results:

    1.) The starter will activate and will turn over the engine.

    2.) The starter motor won't do a thing.

Let's see what your test results mean:

CASE 1: The starter motor cranked the engine. This is the correct and expected test result and confirms the starter motor itself is functioning correctly.

Since the starter motor isn't cranking the engine when you turn the key to crank it, the next step is checking it's receiving an activation signal. Go to: TEST 2: Verifying The 12 Volt Start Signal.

CASE 2: The starter motor DID NOT crank the engine. This test result usually tells you that the starter motor is bad and needs replacement.

Before replacing the starter motor, your next step is ensuring that the cable connecting the starter motor to the battery positive (+) terminal is OK. Go to: TEST 3: Voltage Drop Testing The Battery Cable.

Chevrolet Vehicles:

  • S10 Blazer 2.8L
    • 1988, 1989
  • S10 Pickup 2.8L
    • 1988, 1989, 1990, 1991 1992, 1993

GMC Vehicle:

  • S15 Jimmy 2.8L
    • 1986, 1987, 1988, 1989
  • S15 Pickup 2.8L
    • 1986, 1987, 1988, 1989, 1990
  • Sonoma 2.8L
    • 1991, 1992, 1993