Coil and ICM Input Test

[Edgeauto]

DIY Coil and ICM Input Test
Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk.

I have notice a few threads with people with no start/cutting out problems, so i thought i would make a DIY article to try help out. NOTE these specs are an average as most models have different specs so if you readings are close they are probably correct.

Undo the 3 bolts and remove the distributor cap. Remove the rotor button, it may have a screw in it if so remove it if not use a screwdriver to gently pry it off. Then remove the leak cover.

http://www.edgeautomotive.com.au/images/Image025.jpghttp://www.edgeautomotive.com.au/images/Image024.jpg


IGNITION CONTROL MODULE INPUT TEST

1. Remove the wires from the ICM

2. Turn the ignition switch to ON. Check that there is battery voltage at the wire that came off terminal C and body ground

3. With the ignition still on check there is battery at the wire that came off terminal B and body ground. If there is no voltage test your coil.

4. Check for continuity between the wire that came off terminal D and the ECU

5. Check for continuity between the wire that came off terminal A and the Tacho

6. If all test are normal replace the ICM

http://www.edgeautomotive.com.au/images/Image028.jpg

TESTING A COIL

1. Grab your multimeter and put it on the Ohms setting. Measure the Primary Windings resistance between the A and the B terminals, it should be about 0.7 Ohms.

2. Now change your settings to Kohms and measure the Secondary Windings resistance between the A and secondary winding terminal C, it should be about 17 Kohms.

http://www.edgeautomotive.com.au/images/Image027.jpg

[ECU-MAN]

absolutly awsome DIY dude. love your work

this should come in very handy like you said, very common problems start here.

good stuff

[solitz]

good work champ...nice labeled diagrams btw

[ThEbLaCk]

Thanks alot. I haven't tried it yet since the car is fine now after fixing up the relay.

Where are the wiring for the ECU and Tacho by the way?

Nice work champ once again.

[Edgeauto]

Tacho=instrument cluster

ECU=OBD0 pinB15=OBD1 pinA21

[Kaji-FMP742]

Hate to sound like a noob, but if I were driving at 100km/h and the car just randomly dropped power, then picked back up again, I should do this test? I'm running an F22A6. Honda motors are new to me. :)

[Jazzle]

does it happen only at 100km/h or more?

[dsp26]

+rep for you... even though replaced the icm coz i knew the icm was rooted.. this would have been awesome earlier

however, my issues was getting erratic tach signal at high rpm due to a semi-rooted icm cause by spark leak.

i'm assuming it would have still shown continuity right? or it would have had some sort of resistance?

***EDIT***
oops already repped you a while back and forgot about it :p

[Edgeauto]

Yes it would still have continuity. A erratic tacho is a tell tail sign of a rooted icm and sometime accompanied by an engine miss too.

[Kaji-FMP742]

... engine drops with the tacho wiggle!

Thanks man! I was scared as hell it'd be some strange unfathomable thing. This forum's already saved me from expense!

[dsp26]

just wanted to add this vid:
http://www.youtube.com/watch?v=qYs67zlcKCo

the faulty over-revving is a result of a dead/dying icm.

Thanks to cristian for taking the vid

[Kaji-FMP742]

That engine sounds delicious.

.. do B20As sound similar? Or should I just continue on my quest to find an H22A Accord halfcut on this side of Australia? (there was one in WA recently..)

[omgzilla]

Just a note I thought I'd add:

Not sure if its the same on other motors, but for the B16A2 you have to get the rotor button in position 1 in order to be able to remove the rotor button screw, to take off the rotor.

Just a heads up as I nearly got tricked into trying to pry the thing off lol

Thanks heaps for this tutorial! The coil resistance specs helped me come to a conclusion of condemning my ign coil... $150 later and she's running again ;)

Cheers

[teh_mechanic]

this is exactly the kind of thread i was looking for.
my b16 intermittently misfires above 7000rpm and the tacho needle goes crazy.
I assumed it was ignition related now Im leaning towards a faulty ICM,however I will do these tests on it and the coil tommorro,hopefully they read to be faulty,meaning ive found the problem and i can sleep again lol.

Will let this thread know of the outcome if I replace one of the two
+1rep for you
......

did the test,coil showed 17.5kohms,nothing too bad,but anyway,i changed the coil with 1 i had lying around from a crv b20 dizzy,and my misfire is now gone.so it was the coil causing my problem

[Klayemore]

Good Writeup.

I'm having problems starting my B20. Cranks fine, but sometimes it just will not fire. It's a pain because sometimes it will, sometimes it won't. Could this potentially be the source of my problem? I also have an external coil setup.

Cheers,
Klaye

[ECU-MAN]

sounds like the main PGMFI relay.

when she wont fire how long does it take to get it running ?

[Edgeauto]

As ECU-MAN said check your main relay. Normally if you ignition components fail they die for ever, the only exception is the coil may play up a little then die but normally they also just die.

[Klayemore]

Thanks for the replies.

I only replaced the main relay about a year or so ago (second hand) because it was giving me issues. I thought it was a sign that the main relay was gone if the starter motor won't go? The starter motor always cranks fine, but it just does not fire. You would know more than me though so correct me if I'm wrong.

ECU-MAN: Sometimes I will start no dramas at all, sometimes it may take quite a few cranks to get it started, sometimes it will just crank but not fire at all. It's very annoying but I don't want to take it to a mechanic. Just need to find the time to check it over myself.

I was thinking either ignition or fuel filter, but if you think it could be the relay then let me know.

[ECU-MAN]

as above, sometimes an ICM when hot can take 30 min to start again, but it does sound like the main relay. try the resolder DIY on here.

[B147ch]

LOL loved that clip!
20K RPM VTEC GOGOGOGOGOOOO!! HAHAHA

i think my coil has shit itself, will try this with a multimeter
not throwing spark, scared the crap outta me when i turned my car on, jumped outta the car and it just turned off by itself!
def not my ICM as before it died, my tacho wasnt going beserk or anything..

[dsp26]

dammit i forget about this awesome thread.

I killed my coil and zapped myself on the chassis by holding a plug with pliers against contact C on the coil lol.

[B147ch]

ok so do i remove just the cap, or the whole dizzy to test coil?
im a bit noobish to this whole electronics thing but do i remove the coil from the dizzy to test?
or leave attached?
thanks

[dsp26]

- UNPLUG THE 2 CONNECTORS
- remove dizzy cap via 3 screws
- remove rotor. Rotor contact has to be facing the front of the car when doing this. the screw holding the rotor is only accessible on directly the opposite (firewall) side. Make sure you have leverage when you do this so as to not round the scerw when you attempt removal. There is thread locker on this from factory and you really have to crack it loose first go.
- remove the inner plastic cover
- and then your coil is right there. you don't need to remove it as contact points ABC outlined in the original post all face forward and are accesible once the inner plastic is off


the reason i said remove the 2 plugs is because you may have to crank the car a few times just to get the rotor in the right position. you can shock yourself and kill the coil and/or icm if you crank the dizzy while power is connected to it and the built charge has nowhere to go. trust me i killed my coil this way on the weekend and got zapped

[B147ch]

sweet thanks bro..
u just saved me from potential zapping lol
gonna test my coil this arvo after work.
cheers

[B147ch]

thanks for the help guys!
found out my coil was rooted n hey presto she fired up after installing a new one!

Reps to you guys!

[dsp26]

OK just wan't to add to this thread a new discovery and warning

Signs of a dying ICM:
car starts misfiring randomly on idle and cruise and consistently after 5000rpm. redlining the car, the tacho will look like this:
http://www.youtube.com/watch?v=qYs67zlcKCo

Consequence:
Because it is electronically misfiring, any charge built up in the coil that doesn't discharge when it's supposed to WILL kill the ignition coil. This to me on 2 coils on the weekend.

Which means if your trying to rotate the rotor to get in a position to be removed by cranking the engine, UNPLUG the 2 plugs to the dizzy so no power/charge goes to the coil.

Nothing worse than killing dizzy parts while trying to service it with new rotor/caps/etc