TEST 1: Applying 12 Volts To The Starter Motor S Terminal
The first test we're gonna' do is apply battery power (12 Volts) to the starter motor solenoid's S terminal.
The fastest, safest, and easiest way to do this is using a remote start switch. You can see an example of this tool (and where to buy it), here: Sunpro Actron CP7853 Remote Starter Switch.
If the starter motor cranks the engine, when applying 12 Volts to it, then you can conclude that the starter motor is OK and that some other problem is keeping it from cranking the engine.
IMPORTANT: Before you perform this test remove the key from the ignition switch to prevent the engine from accidentally starting. If your Ford Ranger is equipped with a standard transmission, place it in neutral.
IMPORTANT: Place your Ford Ranger on jack stands if you raise it to access the starter motor!
OK, these are the test steps:
- 1
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. - 2
Attach one of the alligator-type terminals of the remote starter switch to the S terminal of the starter motor.
- 3
Reconnect the battery negative (-) cable to the battery negative post.
NOTE: Make sure that the battery cables and posts are clean. - 4
Connect the remaining alligator-type terminal of the remote starter switch to the battery positive post.
IMPORTANT: If your Ford Ranger has a standard transmission, make sure it's out of gear before you make this last connection. - 5
Activate the starter motor with your remote starter switch. As you apply these 12 Volts (to the S terminal of the starter motor), you'll get one of two results:
1) The starter will activate and will turn over the engine -OR- 2) The starter motor won't do a thing.
Let's examine your test result:
CASE 1: The starter motor cranked the engine. This test result lets you know that your Ford Ranger's starter motor is OK and functioning.
If the starter motor is NOT cranking the engine when you turn the key to start it, then it's probably not receiving the activation signal from the ignition switch.
To further test this, go to the next test: TEST 2: Verifying The Start Signal.
CASE 2: The starter motor DID NOT crank the engine. This usually means that your Ford Ranger's starter motor is bad and needs to be rebuilt or replaced.
I suggest 2 more tests and these are make sure that the starter motor is getting its 12 Volt signal signal and to test the battery cable (that attaches to the starter motor solenoid) for corrosion. This can be accomplished very easily with a voltage drop test.
If the above two tests confirm that the start signal IS present and there's no voltage drop on the battery cable (feeding battery power to the starter motor), then you can confidently conclude your Ford Ranger's starter motor is bad and needs to be replaced.
TEST 2: Verifying The Start Signal
If you've reached this point, then you've confirmed that the starter does crank the engine only if you directly apply power to the S terminal of the starter solenoid.
The next step is to check that the starter motor is receiving the Start signal when you turn the key to start the engine.
You can use a 12 Volt test light for this test or multimeter (the test instructions below call for a multimeter).
OK, let's get started:
- 1
Connect the red multimeter test lead to the S terminal of the starter motor.
- 2
Attach the black multimeter test lead to a clean and rust-free spot on the engine or on the vehicle frame.
I recommend that you use a battery jump start cable to Ground the black multimeter test lead directly to the battery negative (-) terminal. - 3
Have your helper crank the engine from inside your Ford Ranger.
The engine won't turn over, but the idea is to verify that the starter motor's internal solenoid is getting the 12 Volt start signal from the ignition switch (or not). - 4
Your multimeter is going to register one of two results: Either 9 - 12 Volts DC or no voltage at all.
Let's analyze your test result:
CASE 1: The multimeter registered 10 to 12 Volts. This is the correct test result and tells you that the starter motor is receiving its activation signal.
This test result eliminates the safety neutral switch and the ignition switch as being faulty. The next step is to do a voltage drop test on the starter's battery cable. For this test go to: TEST 3: Voltage Drop Testing The Battery (+) Cable.
CASE 2: Your multimeter DID NOT register 10 to 12 Volts. This result tells you that the starter motor is not getting its activation signal. Without it, the starter motor will not crank the engine when you turn the key to crank and start the engine.
Usually, when the starter's activation signal is not present on the wire that connects to the starter solenoid's S terminal, it's usually because:
- The ignition switch is faulty.
- The starter relay is defective.
- The neutral safety switch is faulty or misaligned.
Although it's beyond the scope of this article to test the neutral safety switch, the starter relay, or the ignition switch, you have eliminated the starter motor as defective.
