xX89RSXx

iTrader: (1)

89 RS 305

Car has always been running strong, last week driving on the highway engine just dies. Would turn but not start. Had a feeling it was the module. Coil tested good with my meter, plugs, wires, cap & rotor all good. Brought module to be tested today, definitely dead. Put the new one in today, car fired right up. Let sit idling for about 10 min then took for a test drive. 15 - 20 min later same thing, just dies and wont start. I have yet to pull the new module, but I bet something else is frying it. It was not too hot today and I did use the grease with the module. Didn't notice bad wiring. Anyone else experience this?

Tuned Performance

iTrader: (92)

If The ign coil is going out it can fry the icm. Although I did replace a icm once and a week later the pickup coil went out.

Tuned Performance

iTrader: (92)

http://easyautodiagnostics.com/gm_ic...n_module_1.php
http://www.autozone.com/autozone/rep...00c152800a98f4

Zane M

iTrader: (1)

On the advice of a trusted mechanic, I always replace the pick up coil(provided there aren't issues with the dizzy) at the same time I do the ICM. I also replace the coil since they aren't expensive. Then I know things should be good.

xX89RSXx

iTrader: (1)

Even if the coil and pickup tested good?

kauboy

Think about it, the cost of a pickup coil and ignition coil is less than a tow charge, not to mention the dangers and frustration of getting stuck on the freeway.

motokid108

Sorry to bring up an old thread, but i just fried my 4th or 5th ICM. My car's barely been on the road a year. Whenever im getting on it or letting it rap out, it fries the ignition. I've lost 4 ICM's and a coil so far. Literally melted the coil. Began after i replaced the exhaust system. Manifolds to headers. Checked and tightened all grounds, but still fried it.

bestracing

Saying that you lost a coil, I would say that that could have took out your ICM modules prior to replacing it. Depending on the failure it could have been degrading over time before it totally failed. With that said, I haven't had this happen to me.

My brother's 86 Camaro had a bad ignition miss at 4K rpms or higher. While he was trying to track down the problem he replaced the plug wires (helped a little), distributor cap and rotor (no help) and then had his ignition module tested. Turned out it was bad. bought a new one and the car ran worse. Took it back and it was bad. Before leaving the store with another one they tested the replacement and out of the box it was bad too. They grabbed another one off the shelf and that one was good. So he got 2 bad modules straight from the store. Hasn't had a problem since.

I'd also check the wiring around the back side of the motor for any melted insulation and if it is sitting too close to the headers. I've seen a couple of 94-97, LT1 cars that after headers were installed they started to have electrical problems. Turned out that the wire loom looked okay but the insulation on some of the wires had melted and would short out.

Just a few thoughts off the top of my head. You always start from "what changed prior to this happening". Check and see if something to damaged or broke and then go from there.

85Z28NOS

iTrader: (2)

I had similar trouble when I was using an aftermarket coil. Went back to stock coil and problem went away

motokid108

Well i fried 2 ICM's, then melted the coil, and just the other day fried my 2nd ICM since changing the coil. Ill take a look at the wiring in the back of the motor

bestracing

One year while at the US Nationals I talked to a VP at the MSD display trailer about getting a better ignition coil for an external HEI ignition and he told me to just stick with the stock GM coil that they couldn't offer anything better just an equivalent to what I had.

I have used MSD plug wires, ignition boxes, distributors and coils for many years in our family's race cars (90-13) with no problems what-so-ever but when it comes to HEI coils I have always used GM's coils and they have worked great!

InfernalVortex

iTrader: (4)

I've had 2 Accel modules and 1 accel coil fry itself on me over 2 years. I just stick with factory type GM replacement ignition parts at every turn now. Borg warner, AC delco, etc...

OrangeBird

iTrader: (1)

Hi Gents ,

Since one of my other hobbies is electronics , I'm kinda well versed in transistor operating environments . Our ICM in our dist is at it's basic description an electronic switching device that takes the little pulse of the pickup coil and turns it into a great big pulse in conjunction with the ignition coil . Now , as you all know , this big ol transistor gets HOT while it's doing it's job of pulsing the coil to make the big sparks and so is mounted to the distributor with a bit of manufacturer supplied goo . This goo is rightly called "thermal compound" and to be forward , the stuff supplied with every ICM I have ever bought is GARBAGE and needs to hit the trashcan pronto ! Ya then hop on over to your local Radio Shack and pick up a tiny tube of their best thermal compound and use that . You must , of course , totally clean ALL of the old stuff off of the distributor and use only enough of the new stuff to slightly squish out from under it when it's tightened down . I use this stuff on every ICM I replace , and have NEVER replaced one twice !

Now , of course , there can be other troubles that repeatedly damage ICMs , but the heat issue above is #1 suspect . Number two would be the coil who has begun to develop shorted primary windings , and as the windings short (and their resistance lowers) their current draw raises and overheats the ICM to destruction . Suspect #3 would be , believe it or not , and intermittent connection that gives an occasional arc as it breaks and makes , these can cause current spikes in the circuit to damage the transistor as well . Good clean electrically solid connections are key here .

If you keep your ICM cool , don't ask too much current of it with a defective coil , and feed it nice clean electricity , it should live a long and productive life of makin sparks for ya , just like mine do

PS , I realize the "good stuff" at the shack , even in the little tube , is like $10 or $15 Dollars . I will put that up against the cost of a tow anytime , and even though the tube is tiny , you use so little of it that you could likely replace 2 or 3 ICMs using just that one tiny tube .

Tibo

iTrader: (15)

I believe you are telling the truth. Through college I worked as a manager at AutoZone and it (defective electronic sensors/modules) became such an issue that it was decreed from high up the chain in management (at least regional) that we must test every ICM/starter/alternator before it left the store. Before that new rule I had a bad ICM and bought a new one from them. Put it on the car and had the same problems persisting. Took it off brought it in and it tested bad!

bestracing

I work in the micro electronics industry and what init4fun has posted is VERY accurate. To me it's common knowledge and I tend to forget to add small, although important, stuff like this.

OrangeBird

iTrader: (1)

Thank You bestracing . Sorry I missed your response till now , it seems this subject has just come up in the six cylinder section , and there is at least one gent who believes that NO heat sinking of any kind is needed for an ICM . I'm not sure where one would get such a notion , but it most certainly is a mistaken one ...

willexoIX

Correct. As an Electronics Engineer and a computer tech, any/all heat sources need to be heatsinked(where practical). Obviously an engine has a cooling system, the rad acts as the heatsink. If you run a desktop or laptop cpu without thermal paste or a heatsink and I can guarantee you that it will last about 10 seconds at best.

As for the thermal paste, if you can get the best that money can buy, your ICM should last a great while, providing everything else in the ignition system is functioning as it should.