STARTER TEST 2: Verifying The Start Signal
In the previous page you confirmed that the starter motor does crank the engine when you apply 12 Volts with a remote starter switch. This usually indicates that the Start signal is missing, either because of a bad ignition switch or a bad neutral safety switch.
In this test step, you're gonna' check to see if the ignition switch is sending a Start (Crank) signal to the starter motor solenoid's S terminal.
You can use a multimeter or a 12 Volt automotive test light, the choice is yours (although I prefer to use a multimeter).
OK, enough yakking, here's what you'll need to do:
Select Volts DC Mode on your multimeter and with the red multimeter test lead, probe the S Terminal of the starter motor solenoid. Or better yet, if you have a wire piercing probe to attach to your multimeter, pierce the wire instead.
In case you're wondering which one is the S terminal, the starter motor on your Honda only has two wires attached to it. One wire is attached with a nut and this bad boy goes directly to the battery positive post. The other wire, which is the S Terminal, attaches to the starter motor using a female spade terminal.
Now, Ground the black multimeter test lead on a clean and rust-free spot on the engine or directly on the battery negative (-) terminal.
When ready, have a helper crank the engine. Now the engine won't crank, but this is the only way to test and confirm the presence of the Start signal from the ignition switch (and by extension, verifying that the neutral safety switch is working too).
Your multimeter is going to register one of two results:
1.) If the ignition switch and the neutral safety switch are doing their jobs, you'll see 10 to 12 Volts on your multimeter.
2.) If the ignition switch or the neutral safety switch is fried, your multimeter will not register any voltage.
Let's find out what your test results mean and what the next steps are:
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 let's you know that both the ignition switch and the neutral safety switch are doing their job and supplying the Crank (Start) Signal.
Now, around 90% of the time, you could stop here and condemn the starter motor as bad and replace it and the problem would be solved. But to be absolutely sure, I suggest doing one more test.
The next test would be to voltage drop test the battery positive wire that connects to the starter motor with the nut. This is an easy and fast test, go to: STARTER TEST 3.
CASE 2: If your multimeter DID NOT register 10 to 12 Volts. This tells you that the either the ignition switch or the neutral safety switch is bad. Without this Start (Crank) signal, the starter motor will not come alive and crank the engine.
Now, it's beyond the scope of this article to test either the ignition switch or the neutral safety switch, but you have at least eliminated the starter motor itself as bad.
STARTER TEST 3: Voltage Drop Testing The Bat (+) Cable
One of the things I've seen a lot, that will keep your Honda from cranking and starting, is hidden corrosion on the battery positive (+) terminal. As you may already know, this is the cable that provides the starter motor will the juice it needs to crank your Honda car or mini-van.
If this cable is unable to deliver all of the battery's available power, then the starter motor won't be able to crank the engine.
This is where the voltage drop test saves the day since it will give you a ‘YES this circuit is OK' or a ‘NO, this circuit has a problem’ type test result. Alright, here's what you need to do:
With your multimeter still in Volts DC mode, probe the stud on the starter motor, that has the big cable attached to it with a nut (see the photo in the image viewer), with the red multimeter test lead. Do not probe the cable's round terminal, probe the stud itself.
With the black multimeter test lead, probe a clean spot right in the center of the battery positive post. Do not probe the battery positive (+) terminal, but the center of the battery positive post.
When you're ready, have your helper crank the Honda while you observe the multimeter.
Although the starter motor won't crank the engine, a voltage drop test of this cable (circuit) requires that you turn the key and crank the engine.
Once again, you'll get one of two results on your multimeter:
1.) The multimeter will register a 0 Voltage which indicates no voltage drop.
2.) The multimeter will register a Voltage, usually 5 Volts or more and this test results means that there is a voltage drop in the circuit and this is not good.
OK, now that the testing part is done, let's take a look at what your results mean:
CASE 1: Your multimeter indicated NO voltage drop (which is 0.5 Volts or less): this confirms that the battery positive cable is corrosion free and supplying all of the available battery power to the starter motor.
With this test result you can replace the starter motor with confidence. Now, in case you're reading this article because you've already replaced the starter motor and that did not solve your 'no-crank' condition, I recommend doing the following tests:
1.) Turn the engine manually (using a 1/2 ratchet and the appropriate socket). This will verify that the engine is not mechanically locked up. After all, it could've thrown a rod and this is what is keeping the engine from cranking. Or the A/C compressor could be locked up too (I have seen this a lot!) and this will also make you think it's a bad starter motor.
2.) Bench test the starter motor. You could have received a defective starter motor right out of the box! Bench testing a starter motor is easy and you can find the step-by-step instructions here: How To Bench Test A Starter Motor (Step By Step) (at: easyautodiagnostics.com.
CASE 2: Your multimeter registered 5 Volts or more. This result confirms that a voltage drop indeed exists in this circuit. In non-technical terms, this means that corrosion is keeping the cable from delivering all of the battery's available power. This corrosion almost always shows up on the terminal ends of the cable.
To solve this issue all you have to do is clean both ends of the battery positive cable. By both ends I mean the end that connects to the battery positive post and the end that attaches to the starter motor solenoid. In case you're wondering how to clean the end that attaches to the starter motor solenoid, you can use sand paper to sand both sides of the round terminal.
Once you're done and have reconnected both ends of the cable, re-test or simply crank up the car. More than likely it'll now crank and start.