How to Test a BAD  Starter Motor (Ford 3.0L, 3.8L)

If your Ford 3.0L or 3.8L vehicle Does Not Crank, and you suspect the starter motor and need to test it... this is the starter motor test ‘How To’ article you need. I'll show you how to test the starter motor while it's still in the car (or mini-van) in 2 easy tests.

You don't need any expensive testing or diagnostics equipment to follow the step-by-step test instructions. All you'll need will be a multimeter, a jack and some jack stands.

This Ford starter motor article applies to quite a few Ford, Lincoln and Mercury 3.0L and 3.8L V6 equipped vehicles, 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 and next links.

Here are the contents of this article at a quick glance:

  1. STARTER TEST 1: Verifying the S Signal.
  2. STARTER TEST 2: Voltage Drop Testing the Battery (+) Cable.
  3. Symptoms of a BAD Starter Motor.
  4. Related Test Articles.

Just a reminder: The info presented here is for an On-Car Test of your starter motor. The photos, of the starter motor, I'm using show it out of the vehicle... this is just to explain the test a little easier. On your vehicle, do not remove the starter motor to test it per the instructions presented here.

STARTER TEST 1: Verifying the S Signal

How to Test a BAD  Starter Motor (Ford 3.0L, 3.8L)

Before you start the starter motor tests, it's important that the battery in your vehicle be completely charged, since a discharged battery can give you the false impression that the starter motor is the one causing the Does Not Crank Condition.

Also, the battery posts and terminals must be clean! If they're dirty (full of corrosion)... they could also be the cause behind your No Crank Condition.

One last thing: you'll need to access the starter motor from underneath your car or pick-up or mini-van. So, you'll need to raise it up with a jack. Please use jack stands to hold the vehicle up in the air for the duration of the starter motor tests. Do no trust the jack at all! Think and breathe safety and take all necessary safety precautions.

OK, enough yakking... here's the first test:

  1. 1

    With the car (or pick-up or mini-van) up in the air, place your multimeter in Volts DC mode.

  2. 2

    With the RED multimeter lead, probe the S terminal of the starter motor solenoid. Hold the RED multimeter Lead in this position for the duration of this test.

    In case you're wondering which one is the S terminal. This is the smaller of the three studs on the starter solenoid. To this stud, is attached the wire (circuit) that delivers the Start (Crank) signal from the ignition switch (enlarge the photo in the image viewer... the orange arrow points to this S terminal).

  3. 3

    Now, ground the BLACK multimeter lead. You can accomplish this by touching (with the BLACK multimeter Lead) a clean and rust-free spot on the engine or on the vehicle frame.

    Here's a suggestion: It may hard to near impossible to find a clean and rust-free spot underneath your vehicle, so my suggestion to you is to use a jump start cable to ground the multimeter lead to a good ground spot on the engine (from the top of the vehicle) or directly on the battery negative terminal.

  4. 4

    When you're ready, have your helper to crank the engine.

    Your starter motor won't turn over the engine, of course, but this is what the test requires. What you're doing here is verifying that the ignition switch and the transmission neutral safety switch are OK and delivering the Crank (Start) Signal to the starter motor solenoid's S terminal.

  5. 5

    Your multimeter is going to register one of two results: Either 10 to 12 Volts DC or no voltage at all.

    Alright, let's interpret the results of this test...

OK, let's make sense of the readings that your multimeter recorded in the test:

CASE 1: If your multimeter registered 10 to 12 Volts: This test result confirms that both the ignition switch and the neutral safety switch (on the transmission) are working beautifully.

You could stop here and declare the starter motor as BAD and replace it. Most folks do and about 90% of time, they've solved the No Crank Condition. But, I suggest that you do one more test to be 100% sure that the starter motor is indeed fried. This next test is a voltage drop test and I'll show you how to do it in STARTER TEST 2, go to:   STARTER TEST 2: Voltage Drop Testing the Battery (+) Cable.

CASE 2: If your multimeter DID NOT register 10 to 12 Volts: This result let's you know that the starter motor on your Ford car, or pick-up, or mini-van is not the cause of the problem.

Here's why: Without the Start signal from the ignition switch, the starter motor will not activate to start cranking the engine. Or if the ignition switch is good and sending the Start Signal, but the neutral safety switch is not completing the circuit, for this Start Signal to reach the starter motor solenoid, the starter motor will not crank the engine.

Although this article does not cover how to test the ignition switch or the neutral safety switch... you have at least eliminated the starter motor as BAD on your 3.0L or 3.8L equipped Ford or Mercury or Lincoln car, mini-van, or pick-up.