Testing the starter motor to determine if it's failed or is still good isn't difficult. In this tutorial, I'll show you the three tests I use to see if the starter motor has kicked the bucket and is preventing the engine from cranking.
With your test results, you'll quickly find out if the starter motor is good or if it's failed and needs replacing to get the engine cranking again.
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 van only to explain the test connections better.
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- 4.2L V6 Ford E150: 1997, 1998, 1999, 2000, 2001, 2002, 2003.
- 4.2L V6 Ford E250: 1997, 1998, 1999, 2000, 2001, 2002, 2003.
Starting System Wiring Diagrams: The following wiring diagrams are available to help you further troubleshoot the starter motor on your van:
- Starter Motor Circuit Wiring Diagram (1997-1998 4.2L V6 Ford E150, E250).
- Starter Motor Circuit Wiring Diagram (1999-2003 4.2L V6 Ford E150, E250).
Important Testing Tips
TIP 1 - Make Sure The Battery Is Fully Charged: So that you get the most accurate test result from your starter motor test, the battery needs to be fully charged. A weak or dead battery can mimic a starter motor problem and skew your test result.
TIP 2 - Clean Battery Terminals: Clean any corrosion on the battery cable terminals and posts. Corrosion can hinder the current flow to the starter motor, impacting its ability to crank the engine and skewing your test results.
TIP 3 - Use Jack Stands for Safety: If you need to lift your van to reach the starter motor, don't rely solely on the jack. Use jack stands to securely support the van while you work underneath. Be careful and always think safety.
TIP 4 - Wear Safety Glasses: Protect your eyes by wearing safety glasses when working under the van. Be careful and always think safety.
TIP 5 - Avoid Moving Parts: Stay mindful of belts, pulleys, and fans that are gonna spin when the engine is cranked for the starter motor test. Keep hands and tools clear of these moving parts to prevent injuries.
TIP 6 - Remove the Ignition Key: Taking the key out of the ignition switch prevents the engine from starting if the starter motor is functioning properly.
Symptoms Of A Bad Starter Motor
The component in charge of turning the engine over for it to start is the starter motor. It's a hard worker and eventually, it'll wear out and malfunction. When it does malfunction, it'll usually cause one of two problems:
- Engine no-crank problem: When the starter motor has completely failed, the engine won't crank at all when you try to start it.
This means when you turn the key, you'll hear nothing or maybe just a click, but the engine won't turn over. This is the most common result of a bad starter motor. - Intermittent engine no-crank problem: In this case, the starter motor works most of the time, allowing the engine to crank and start normally. However, occasionally, the starter will fail, causing the same "no-crank" issue as a complete failure.
This is frustrating because it's unpredictable. One time the engine starts without a problem, and the next time, it won't crank at all. This intermittent failure makes it harder to diagnose and fix.
NOTE: If you're troubleshooting an intermittent no-crank problem, it's important that you test the starter motor when it's not cranking the engine. If the engine starts cranking, the starter motor will pass any and whatever tests you perform on it and the underlying issue will not be pinpointed.
Tools Needed To Test The Starter Motor
The following is the list of tools that I use myself and that I recommend for testing the starter motor. Nothing that'll break the bank and they definitely make the whole testing procedure easy and safe:
- A jack.
- You'll need to raise your van to access to the starter motor.
- Jack stands.
- A remote starter switch.
- If you'd like to see what a remote starter switch looks like, you can follow this link: Actron CP7853 Remote Starter Switch For 6V And 12V Automotive Starting Systems.
- You can either buy this tool online, or you can buy it at your local auto parts store (AutoZone, O'Reilly Auto Parts, etc.).
- A multimeter or a 12 Volt automotive test light.
- If you don't have a multimeter or need to upgrade yours, check out my recommendation here: Buying A Digital Multimeter For Automotive Diagnostic Testing.
- A wire piercing probe.
- This tool isn't an 'absolute must-have tool,' but I can tell you from experience that it makes it a whole lot easier to probe the S terminal wire for the Start Signal.
- If you'd like to see what this tool looks like, you can find out more about it here: Wire Piercing Probe Tool Review (Power Probe PWPPPPP01).
- A helper.
TEST 1: Applying 12 Volts To The S Terminal
The starter motor receives a 12-Volt activation signal from the ignition switch to activate and crank the engine.
This activation signal is delivered to the S terminal on the starter motor's solenoid (see the illustration above).
For our first test, we're gonna apply 12 Volts directly to the S terminal, bypassing the ignition switch, and see if the starter motor activates and cranks the engine.
NOTE: Using a remote starter switch to apply 12 Volts to the starter motor solenoid is the safest and easiest way to accomplish this test section. Take all necessary safety precautions when working around a cranking engine.
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 Ford pickup is equipped with a standard transmission, place it in neutral.
S Terminal ID: Look for the thinner wire among the two that connect to the starter solenoid. Follow this wire to the smaller threaded stud on the solenoid. This is your S terminal.
OK, let's get testing:
- 1
Raise the front of your van and place it on jack stands (to gain access to the starter motor).
- 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
Attach one end of the remote starter switch to the battery positive (+) post.
- 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
Reconnect the battery negative (-) cable to the battery negative post.
- 6
Apply 12 Volts to the S terminal wire of the starter motor starter solenoid with your remote starter switch.
- 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.