As a do-it-yourselfer, you have two choices when it comes to testing the starter motor, you can either remove it and have it bench tested at your local auto parts store (AutoZone, O'Reilly Auto Parts) 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 that now if the starter is good you've wasted the time and effort removing and reinstalling it.
The best option is to test it yourself while it's still on the car. In this tutorial, I'll walk you through the entire starter motor testing process step by step. You'll definitely be able to say, 'yes, it's bad' -or- 'No, it's not bad'.
Contents of this tutorial:
- Important Safety Precautions.
- Symptoms Of A Bad Starter Motor.
- Tools Needed To Test The Starter Motor.
- TEST 1: Applying 12 Volts To The Starter Motor S Terminal.
- TEST 2: Making Sure The Starter Is Getting An Activation Signal.
- TEST 3: Voltage Drop Testing The Battery (+) Cable.
- More 1.8L Nissan Sentra Tutorials.
You can find this tutorial in Spanish here: Cómo Probar El Motor De Arranque (2000-2002 1.8L Nissan Sentra) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 1.8L Nissan Sentra: 2000, 2001, 2002.
Important Safety Precautions
SUGGESTION 1: In the photos I'm using, you'll notice that the starter motor is removed from the vehicle. This is just to show you where to make your connections. You don't have to remove it to use the information 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 tests in this tutorial must be performed with a fully charged battery in your Nissan vehicle. A discharged battery will give an incorrect diagnostic result and waste time and money! In addition, the battery cable connections and battery posts must be clean and free of corrosion.
SUGGESTION 3: To get to the starter and test it, you need to lift your Nissan in the air. So use jacks stands (to keep it up in the air) and don't trust the jack alone! Take all necessary safety precautions, such as using jack stands, wearing eye protection (safety glasses), etc.
SUGGESTION 4: If your vehicle has a standard gearbox, make sure you are out of gear and in neutral and that the parking brake is engaged/applied.
Symptoms Of A Bad Starter Motor
The starter motor in your Nissan Sentra will eventually fail, and when it does, the most obvious symptom is that it will not crank the engine (technically known as a no-crank condition).
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 your vehicle still won't crank.
- When you turn the key to start the engine, all you hear is a light knock and nothing else.
Although the list above is not a very exhaustive list of symptoms, the theme that runs through it and every 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 your Nissan Sentra's starter motor, 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 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, 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 start with the first starter motor test.
TEST 1: Applying 12 Volts To The Starter Motor S Terminal
The starter will activate when it receives a 12 Volts signal on the S terminal wire (this is the wire marked with the letter S in the photo above).
In many cases, this 12 Volts start signal is missing. For our first test, we'll manually apply these 12 Volts to the starter motor ourselves with a remote start switch.
If the starter motor activates when you manually apply 12 Volts, you're confirming two things:
- The starter motor is fine.
- The problem that is preventing your vehicle from starting is due to this missing signal.
NOTE: It can be challenging to get to the S terminal of the starter solenoid (to manually apply 12 volts). I use a wire piercing probe to puncture the S-terminal wire (while it's still connected to the S-terminal) and then I connect my remote start switch to it and go from there. I suggest you do the same. You can see what this tool looks like here: Wire Piercing Probe Tool Review (Power Probe PWPPPPP01).
IMPORTANT: The battery MUST be fully charged for this test (or any of the other 2) to give you a reliable test result!
OK, this is what you'll need to do:
Jack up your Nissan Sentra and place on it jack stands.
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 one of the remote starter switch's terminals 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.
NOTE: In case you're wondering whether or not you can leave the starter solenoid's S-terminal wire connected to the engine's harness connector, the test will work either way.
Reconnect the battery negative (-) cable to the battery negative (-) post.
Connect the remaining remote starter switch 'alligator' type connector to the battery positive (+) post.
Now, using your remote start switch, apply 12 Volts to the starter solenoid's S-terminal wire.
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 take a look at what your test results mean:
CASE 1: The starter motor activated and cranked the engine. This test result tells you that the starter motor is fine and working.
It also tells you that the likely cause of it not working when you turn the key to start the engine is a lack of the 12 Volts start signal at the S terminal of the starter motor solenoid.
The next step is to go to TEST 2 and verify that the starter is getting the 12 Volts start signal on the S terminal wire. Go to: TEST 2: Making Sure The Starter Is Getting An Activation Signal.
CASE 2: The starter motor DID NOT activate. This usually means that your starter motor is bad and needs to be rebuilt or replaced.
I suggest 2 more tests and these make sure the starter motor is getting its 12 Volts start signal and test the battery cable (which connects to the starter motor solenoid) for corrosion. This can be done very easily with a voltage drop test.
For the first of these two tests, go to: TEST 2: Making Sure The Starter Is Getting An Activation Signal.