How To Test The Starter Motor (1997-2014 4.6L, 5.4L V8 Ford E150, E250, E350)

TEST 2: Making Sure The Starter Motor Is Getting An Activation Signal

So far in TEST 1, you've confirmed that the starter motor itself is OK, since it cranked the engine when you directly applied 12 Volts to its S terminal.

The next step is to see if the starter motor solenoid is getting an activation signal on the S terminal wire when you turn the key to crank and start the engine.

We'll use a multimeter to confirm this activation signal, which should be in the range of 10 to 12 Volts.

Here's what you'll need to do:

1. 1

   Raise and place the front of the vehicle on jack stands (if it isn't already).

2. 2

   Place your multimeter in Volts DC mode.

3. 3

   Ground the black multimeter test lead directly on the negative (-) battery terminal using a jump start cable.
   
   You can also Ground it on the engine, if you can find a clean, unpainted and rust-free spot of metal.

4. 4

   Connect the red multimeter test lead to the S terminal wire using an appropriate tool.
   
   Don't know which wire is the S terminal wire? It's the one that connects to the smaller of the three studs on the starter motor solenoid.
   
   The S terminal wire (circuit) is the one that delivers the Start (Crank) signal from the ignition switch.

5. 5

   Have your helper turn the key to crank the engine when the test is setup.

6. 6

   Your multimeter should read 10 to 12 Volts DC.

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

CASE 1: Your multimeter registered 10 to 12 Volts. This test result lets you know the starter solenoid is receiving the activation signal (crank signal).

This means that we can forget about the neutral safety switch and the ignition switch being bad. OK, now the next test is to do a very easy and simple voltage drop test. Go to: TEST 3: Voltage Drop Testing The Battery (+) Cable.

CASE 2: If your multimeter DID NOT register 10 to 12 Volts. This result exonerates the starter motor. Your starter motor is not bad.

Here's the reason why: Without this crank signal, the starter motor will not crank the engine. Now, although it's beyond the scope of this tutorial to test the neutral safety switch or the ignition switch, you have eliminated the starter motor and this means saving money by not buying a part your vehicle does not need.

TEST 3: Voltage Drop Testing The Battery (+) Cable

In this last test section, we're gonna check the positive (+) cable that connects the battery to the starter motor is delivering the full force of the battery's power.

Specifically, we need to make sure that there isn't any hidden corrosion causing a voltage drop. If there is, not all the power from the battery is getting to the starter motor.

Even with a fully charged battery, a voltage drop due to corrosion will prevent the starter motor from cranking the engine.

To make sure that both ends of this cable are corrosion-free (where it connects to the battery or the starter), we'll perform a voltage drop test with our multimeter.

Let's get going:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Attach the red multimeter test lead to the positive (+) battery post. The positive (+) battery post must be clean and corrosion-free.
   
   You may need two helpers for this test step, since someone will have to hold the red multimeter test lead onto the battery positive (+) post and someone else inside the vehicle (to crank it when everything is set up).

3. 3

   Place the black multimeter test lead on the starter motor solenoid stud that connects to the battery positive (+) cable (see illustration above).
   
   The orange arrow with the plus (+) sign, in the illustration above, points to this stud.
   
   Maintain the black multimeter test lead in this position throughout the next step.

4. 4

   When everything is ready, have your helper turn the key to crank the engine.
   
   Although the starter motor won't crank the engine, your helper has to turn the ignition switch to start the engine for the voltage drop test to work.

5. 5

   The multimeter should register 0.5 Volts or less (0.5 V = 0 Volts).
   
   If there's a problem in the wire, your multimeter will register some voltage, usually 5 Volts or more.

Let's take a look at what your results mean:

CASE 1: Your multimeter registered 0 Volts (no voltage drop). This result indicates that the starter motor is receiving all of the battery voltage and Amperage it needs to crank the vehicle.

This also means that the starter motor is bad, if you have:

• Confirmed that the starter motor DOES NOT crank the engine when applying 12 Volts directly to its S terminal (TEST 1).
• Confirmed that the starter motor is receiving its activation signal (TEST 2).
• Confirmed in this test step no voltage drop exists on the battery positive (+) cable.

I'm going to make two more recommendations to you:

• Before removing the starter motor, manually turn the engine using a 1/2 ratchet and the appropriate socket, just to make sure the engine or the A/C compressor have not locked up and causing the no-crank condition.
• Bench test the starter motor after removing it. This is a super easy test to do and you can find this tutorial by clicking here:
  • How To Bench Test A Starter Motor (Step By Step) (at: easyautodiagnostics.com).

CASE 2: Your multimeter registered 5 Volts or more. This result tells you that a voltage drop does exist and this is not a good result.

The good news is that this can easily be corrected, since a voltage drop is always caused by some sort of corrosion issue on the battery positive cable's terminals or the battery positive post.

The solution is to thoroughly clean the battery positive post and the battery positive (+) terminal (both the end that attaches to the battery positive post and the end the connects to the starter motor solenoid).

After the cleaning, crank the engine. If it cranks and starts, you've solved the issue and no further testing is required.

More 4.6L, 5.4L V8 Ford E150, E250 And E350 Tutorials

There are quite a few 4.6L and 5.4L Ford E-Series van 'how to' tutorials and wiring diagrams that you can check out here:

• 4.6L, 5.4L Ford E150, E250, And E350 Index of Articles.

F-Series Pickups: You can find all of the available tutorials and wiring diagrams for the 4.6L And 5.4L V8 F-Series pickups in this index:

• 4.6L, 5.4L Ford F150, F250, And F350 Index of Articles (at: easyautodiagnostics.com.com).

Crown Vic And Grand Marquis: You can find all of the available tutorials and wiring diagrams for the 4.6L And 5.4L V8 F-Series pickups in this index:

• 4.6L Crown Victoria And Grand Marquis Index of Articles.