How to test the coil?

nhlx38 · 08-09-2010, 10:53 AM

How do i test the coil in my 95 jeep wrangler? I dont want to go out and buy a new one and find out that it wasnt the problem.

A link or just a detailed explanation would be very nice.

moonshinefuel · 08-09-2010, 11:58 AM

For me, it would be like going through the trouble to try and test spark plug wires, yet more complex. Not worth it for me.
Coils are not always easy to test. It could show ok on an ohm meter, but if it has a short, you may not see it with an ohm meter. There are different ways to test it, running/not running. But then when you try to test it running, say for one of the windings in the coil, a standard voltmeter may not suffice. They fail over time, not all at once usually, plus the problem can start occurring after it has been running for a while, and not while its cold, or right away sometimes. If your coil is original, and you have considerable miles, I would replace it regardless, but that's just me.

**Louie4** · 08-09-2010, 12:56 PM

I generally use my voltmeter and measure the resistance on the primary and secondary and based on what the values should be from the Haynes I'll decide if I need a new one. You could also take it to Autozone, they have tested coils for me before. Another test is turning the motor over and checking for spark to the distributor from the coil. That wouldn't work though if the CPS was bad.

**Joe Dillard** · 08-09-2010, 01:17 PM

Scroll down to the bottom of this page.

You should see an area called; "Similar Threads".

Click on the bottom thread named; "Test a coil".

You may need to update the link & re-do the search on that website yourself.

nhlx38 · 08-09-2010, 02:27 PM

Thanks, i did take the wire coming out of the coil that is supposed to go into the distributor and grounded it. When I saw no spark coming out of that as i cranked it, i had a pretty good idea that it was shot.

I did attempt to take it to auto zone as well but they said they did not have proper equipment to test my model ('95 rio grande)

I ended up buying a new coil and also a new slater not knowing what exactly it may have been.

But i did end up gettin it to work, thanks for the suggestions tho!