How to test ICM and Coil?

D16z6PN · 12-29-2009, 10:03 PM

How do you check ICM and coil? Do you have to removed both of them from the distributor for testing? What should the reading be for both? You use voltage to check ICM and ohms to check resistance on coil right?

Also, what does a worn distributor rotor and terminal under the cap look like? Picture would be great.

94 stock Civic Ex for your reference.

RonJ · 12-29-2009, 10:12 PM

Quote:

Originally Posted by D16z6PN

How do you check ICM and coil? Do you have to removed both of them for the distributor for testing? What should the reading be for both? You use voltage to check ICM and ohms to check resistance on coil right?

Yes, remove them both for testing. Take the ICM to an auto parts store for testing as there is no easy way for you to test it. The diagram below shows how to test the coil.

Also, what does a worn distributor rotor and terminal under the cap look like? Picture would be great.

Remove the distributor cap. On the inside top of the cap, you will see four metal tabs that make contact with a corresponding metal area on the rotor. The cap and rotor contact points should not be corroded or worn. Post pictures if you are unsure what you are looking for.

What problem are you having?

D16z6PN · 12-30-2009, 03:34 PM

Pretty much the car cranks, but just doesn't fire up and I'm not getting any sparks.

Is it possible to check voltage continuity on the ICM by checking voltage on the middle pron and right pron of the ICM?

I'll have picture of the cap and rotor up later.

RonJ · 12-30-2009, 03:39 PM

Quote:

Originally Posted by D16z6PN

Pretty much the car cranks, but just doesn't fire up and I'm not getting any sparks.

Does the fuel pump prime and do the fuel injectors have battery voltage?

Is it possible to check voltage continuity on the ICM by checking voltage on the middle pron and right pron of the ICM?

The ICM is basically a switch. It's a bit complicated for the average person to test, so most simply take the ICM to an auto parts store for testing. Click here.

D16z6PN · 12-30-2009, 06:48 PM

Fuel pump does prime and I haven't check the battery voltage, but I'm sure its working since I have fuel on my spark plug a few days ago trying to start it.

Anyways, I took the ICM and coil out today. I tested the coil primary winding and got zero not sure if I'm doing something wrong here. I got a reading around 10.88 for the secondary winding while on the car and off the car.

Brought both parts to Autozone. They got around 10 as well for the secondary winding, but not sure what they got for the primary. They told me that the secondary is a little under spec though. As for the ICM they took it to the back and said that their machine was showing it as bad. Pretty much they said I needed to replaced both parts.

Then I brought it to Advance Auto Parts for a second opinion and they tested the ICM right there in front of me. Their machine show that it is good. As for the coil they don't test coil.

Brought it to a locally owned auto parts store for a third opinion. They also tested the ICM in front of me and it show that it was good. As for the coil they got around 10 as well for the secondary winding and somewhere around zero for the primary. They said that its normal for a coil to read around 10 on the secondary and that my coil was fine as well.

What should the spec be for primary and secondary winding for a D16z6? Same as what the picture stated? Even though its a different distributor from mine.

As for my cap and rotor my computer is having trouble upload pictures, but anways the cap doesn't seem to have any crack on it. It has a little carbon, but nothing too much. The terminal under the cap feel rough and is kind white. (Look like the same white mark if you rub a rock against another rock.) Rotor seems rough as well and it has the same white marking on it. I'm not really sure what a normal distributor terminal and rotor should look compare to a worn out one.

What do you guys think it might be?

RonJ · 12-30-2009, 07:12 PM

What resistance scales on your multimeter are your using for the measurements? Did you measure resistance at about room temperature? Your primary and secondary resistance values must be within the ranges posted in the diagram, otherwise the coil is bad.

Sand clean the metal contact points inside the distributor cap and on the rotor with fine sand paper.

D16z6PN · 12-30-2009, 07:37 PM

I measured the secondary on 20k and primary shows zero on all scale. So, I guess I have a bad coil then even though the local auto parts store said it was normal.

I guess I'll sand down the terminal under the cap and rotor as well while I'm at it. Rotor kinda has a small loose thread hanging out though. Can't really see it in the picture, but here they are anyways.

RonJ · 12-30-2009, 07:44 PM

Yeah, if your measurements are correct, then the local auto parts store gave you bad advice as the coil is surely bad.

There's quite a bit of corrosion on the cap and rotor contact points, and this may be what ultimately killed the coil. If the high voltage spark in the coil can't find somewhere to ground, it will burn out. Spend some time getting those contact points clean and shiny.

D16z6PN · 12-31-2009, 12:35 AM

I will do that and let you know what I find out.

Also, do you know if dist rotor, cap and ign coil from a 98 Civic HX will work on my D16z6?

RonJ · 12-31-2009, 01:56 AM

Quote:

Originally Posted by D16z6PN

Also, do you know if dist rotor, cap and ign coil from a 98 Civic HX will work on my D16z6?

Not sure.

D16z6PN · 01-05-2010, 08:08 PM

What's the difference between aluminum and brass cap/rotor beside being more resistant to corrosion and more conductive? Would you recommend brass?

How to test ICM and Coil?

5th Generation Honda Civic (1992-1995)