This is a simple guide that will help you to troubleshoot a BAD starter motor on your 4.6L or 5.4L V8 equipped car, pick up or SUV. This is an On-Car starter motor test that you'll be able to easily accomplish with some basic tools.
To see if this starter motor test article covers your specific Ford 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 and next links.
Here are the contents of this article at a quick glance:
- Important Safety Precautions.
- STARTER TEST 1: Applying 12 Volts To The Starter Motor S Terminal.
- STARTER TEST 2: Verifying The Start Signal.
- STARTER TEST 3: Voltage Drop Testing The Battery (+) Cable.
- Symptoms Of A BAD 4.6L & 5.4L Starter Motor.
- Related Test Articles.
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 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 Ford 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 Volts To The Starter Motor S Terminal
In this first test, we're gonna' use a remote starter switch to apply 12 Volts to the S terminal of the starter motor solenoid. If the starter motor is good, it'll activate and crank the engine.
If the starter motor doesn't activate and crank the engine (after applying 12 Volts to the S terminal), then you've got a bad starter motor on your hands.
By the way, if you don't have remote starter switch and you're wondering what this tool looks like, you can follow this link and take a look at it: Actron CP7853 Remote Starter Switch (you can buy this bad boy online or at your local autoparts store- AutoZone, O'Reilly Auto Parts, etc.).
OK, this is what you'll need to do:
Jack up your Ford vehicle and place on jack stands. You'll need to raise the vehicle to gain access to the starter motor.
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.
Attach a 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.
Reconnect the negative battery cable to the battery negative post.
Now, apply 12 volts to the S terminal of the starter motor starter motor with your remote start switch. 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.
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.