STARTER TEST 1: Applying 12 Volts To The Starter Motor S Terminal
The very first thing we're gonna' do, to find out if the starter motor on your 2.4L Nissan Frontier or Xterra is bad or not, is to manually apply 12 Volts to the starter motor solenoid S terminal.
Since getting to the starter motor solenoid is not that easy, I suggest you use a wire piercing probe to pierce the S terminal wire and then connect your remote starter switch to it and proceed from there.
OK, this is what you'll need to do:
Jack up your Frontier (or Xterra) and place on it jack stands. Remember, to only way to gain access to the starter motor is from underneath your Frontier or Xterra.
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 a 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.
Reconnect the negative battery cable to the battery negative post.
Now, apply 12 Volts to the S terminal wire of the starter motor starter solenoid with your remote starter switch. As you apply these 12 Volts (to the S terminal wire of the starter motor solenoid), you'll get one of two results:
- The starter will activate and will turn over the engine
- The starter motor won't do a thing.
Let's take a look at what your test results mean:
CASE 1: The starter motor cranked the engine. This means that the starter motor is good and that you have an electrical issue keeping the starter motor from cranking the engine.
The next step is to go to TEST 2 and see if the starter motor is getting the Start signal on the S terminal wire (circuit). Go to: TEST 2: Verifying The Start Signal.
CASE 2: The starter motor DID NOT crank the engine. This usually means that your 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 Start 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.
STARTER TEST 2: Verifying The Start Signal
As you may already know, when you turn the key to crank/start the engine, the starter motor gets 12 Volts on the S terminal wire of the starter motor solenoid. These 12 Volts are known as the Start signal.
So, in this test step, we're gonna' see if the starter motor solenoid is getting this Start signal on the S terminal wire. Since you already have your vehicle up on jack stands, this test won't be that hard to do.
You can use a multimeter or a 12 Volt automotive test light. Ok, here's what you'll need to do:
Lift the vehicle and place it on jack stands (if it isn't already up in the air). Now, while underneath the vehicle, connect the red multimeter test lead to the S terminal wire of the starter motor.
The S terminal wire, of the starter solenoid, must remain connected to it's engine wiring harness connector for this test to work.
Attach the black multimeter test lead to a clean and rust-free spot on the engine or on the vehicle frame.
Here I'm going to recommend something to you: Use a battery jump start cable to Ground the black multimeter test lead to a clean Ground point on the engine. The reason why is that depending on how rusty and dirty the underneath of the vehicle, you may NOT be able to find a clean and rust-free spot to Ground the multimeter's black test lead.
Now, have your helper hop inside the vehicle and turn the key to crank the engine.
The engine won't turn over, but the idea is to verify that the starter motor solenoid is getting the 12 Volt start signal from the ignition switch.
Your multimeter is going to register one of two results: Either 10 to 12 Volts DC or no voltage at all.
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 let's you know the starter solenoid is receiving the Start signal (crank signal).
This means that we can forget about the safety neutral 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.
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 10 to 12 Volt Crank Signal, the starter motor will not crank the engine. Now, although it's beyond the scope of this article 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.