As a DIY'er, you have two choices, when it comes to testing the starter motor... you can either remove it and have your local auto parts store (AutoZone, O'Reilly Auto Parts) bench test it for free or you can test it yourself while it's still on the car.
The only thing that stinks about having your local auto parts store bench-test it, is if the starter motor is good... you've now wasted time and effort removing and re-installing it.
The best option, is to test it yourself while it's still on the car. In this tutorial I'll walk you, in a step-by-step manner, thru' the entire starter motor testing process. You'll be able to definitely say: ‘Yes, it's BAD’ -or- ‘No, it's not BAD’.
Here are the contents of this article at a quick glance:
- Important Safety Precautions.
- Symptoms of a BAD Starter Motor.
- Tools Needed to Test the Starter Motor.
- 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.
- Related Test Articles.
Important Safety Precautions
Suggestion 1: You'll notice in the photos I'm using that the starter motor is off of the vehicle. This is just to make it easier to show you where to make your connections. You don't need to remove it to use the info in this tutorial.
If you do need to bench test it (test if off of the vehicle), the following tutorial will help you: How to Bench Test a Starter Motor (Step by Step) (at: easyautodiagnostics.com).
Suggestion 2: All the tests, in this tutorial, need to be done with a fully charged battery in your Nissan vehicle. A discharged battery will cause you to reach the wrong diagnostic conclusion and have you wasting time and money! Also, the battery cable terminals and battery posts must be clean and corrosion free.
Suggestion 3: To get to the starter motor, to test it, you'll need to raise your Nissan up in the air... so, use jack stands (to keep 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: 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.
Symptoms of a BAD Starter Motor
The starter motor, in your Nissan Sentra will eventually fail and when it does the most obvious symptom will be that it will not crank the engine (this is called a No Crank Condition in tech speak).
You'll also see one or several of the following symptoms:
- The engine doesn't turn over (crank) when you turn the key to start the engine.
- A jump start doesn't help. The vehicle's engine still refuses to crank.
- The battery has been charged and/or replaced and still your vehicle does not crank.
- When you turn the key to crank the engine, all you hear is a small knock and nothing else.
Although the above list is a not a very complete list of symptoms... the theme that runs thru' them, and any other related symptom, is that the engine will not turn over when you try to start it.
Tools Needed to Test the Starter Motor
You don't need expensive test equipment to test the starter motor on your Nissan vehicle... but you do need a few things. These are:
- Jack stands.
- 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.
- You can either buy this tool online or you can buy it at your local auto parts store (AutoZone, O'Reilly, Pepboys, etc.).
- 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 (at: easyautodiagnostics.com).
- A wire piercing probe.
- This tool is not 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 find out more about it here: Wire Piercing Probe Tool Review (Power Probe PWPPPPP01).
- A helper.
As you can see... you don't need anything expensive. OK, let's turn the page and get starter with the first starter motor test.