STARTER TEST 2: Verifying The Start Signal From The Ignition Switch
In TEST 1 you verified that the starter motor does come on (to crank the engine) when you apply 12 Volts to it with a jumper wire (or remote start switch).
The next step is to see if the starter motor solenoid is getting the Start signal from the ignition switch.
This Start Signal originates from the ignition switch, then goes through the neutral safety switch (on the transmission) before finally reaching the starter motor solenoid.
This is what you need to do:
- 1
Using a jack, raise the front of the vehicle and place it on jack stands.
- 2
Place your multimeter in Volts DC mode (you can also your an automotive 12 Volt Test Light).
- 3
Locate the S terminal of the starter motor solenoid and with the red multimeter test lead probe this terminal and hold it there for the duration of this test.
The S terminal is the smaller of the three studs on the starter motor. To this stud, is attached the wire (circuit) that delivers the Start (Crank) signal from the ignition switch (in the phot above, the orange arrow points to this S terminal). - 4
With the black multimeter test lead, touch a clean and rust-free spot on the engine or on the vehicle frame.
Here's my recommendation: Use a battery jump start cable to Ground the black multimeter test lead to a clean Ground point on the engine from the top of the vehicle, because 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. - 5
Ask your helper to crank the engine.
Although the starter motor is not going to crank the engine, the purpose of this test is to verify the presence of the Crank (Start) signal from the ignition switch. - 6
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 is good, since it let's you know that the starter motor is getting a crank signal from the ignition switch.
This test result also confirms that the neutral safety switch is good and doing its job. If your starter motor still isn't cranking the engine, when you turn the key to start, then the next step is to check the battery positive cable that connects to the starter motor solenoid.
This can easily be done with a voltage drop test. This is a very easy and simple test to do, and in STARTER TEST 3 'll show you how to do it. Go to TEST 3: Voltage Drop Testing The Battery Cable
CASE 2: If your multimeter DID NOT register 10 to 12 Volts. This result lets you know that the reason the starter motor is not cranking up the engine is through a lack of a Crank (Start) Signal.
Here's why: without this crank signal, the starter motor will not crank the engine. This Signal could be missing because either the neutral safety switch is bad or a bad ignition switch. Testing these two components is beyond the scope of this article but you have now eliminated the starter motor as bad.
