1970 Explorer Class A on a 1969 Dodge M300 chassis with 318 cu. in. (split year)
1972 Executive Class A on a Dodge M375 chassis with 413 cu. in.
1973 Explorer Class A on a Dodge RM350 (R4) chassis with 318 engine & tranny from 1970 Explorer Class A
TreeSeeker wrote:
Ok, here is what the backside of the ICM looks like.
![[image]](http://i63.tinypic.com/2dgq6ti.jpg)
I think I need a new one.
Ok, here is what the backside of the ICM looks like.
I think I need a new one.
Yes, this one has clearly been subjected to excessive heat. With everything you've told me, it has to be internally generated.
So, something, somewhere, between the battery and ICM is creating excessive resistance. The result is low voltage to the ICM. (I=V/R, alternatively E=V/R ... I and E are simply different symbols for the same thing.)
FIND AND FIX THAT! Otherwise, sooner or later, you're going to fry the new ICM, because the cause is still there.
VintageMopar wrote:
And it requires a good clean ground where it bolts to firewall. It originally had cadmium plated screws and star washers to insure this. Mine melted down similiar to that, ran that epoxy resin stuff down the firewall. The only symptom was backfiring out exhaust on deceleration so bad, it blew one of the mufflers out. Changed the module and it stopped it.
And it requires a good clean ground where it bolts to firewall. It originally had cadmium plated screws and star washers to insure this. Mine melted down similiar to that, ran that epoxy resin stuff down the firewall. The only symptom was backfiring out exhaust on deceleration so bad, it blew one of the mufflers out. Changed the module and it stopped it.
Yours is only second time I've hear of this happening, with TreeSeeker's being the first. Never seen it happen personally, with hands-on experience spanning several dozen Mopar vehicles. (Mine as well as other people's)
Yes, good, clean, tight ground connection is one of my mantras.
eyeteeth wrote:
Well then... mine would be the third. Mine is in better condition than TreeSeekers, components are still covered. But it still melted out.
Well then... mine would be the third. Mine is in better condition than TreeSeekers, components are still covered. But it still melted out.
This seems to be a common problem? I wonder if maybe somebody should reverse engineer one and build a better one less prone to failure?
I'm sure there would be a market for them.
Downsizing ">
It certainly appears that my ignitnion control module (ICM) didn't have a good ground. I tried measuring it from the heat sink on the top of the case to ground and there was no continuity, but I didn't know if the top connected to the base.
The base is painted on both sides, so the side touching the firewall was painted and the firewall itself is painted so one would expect that there was no good (or probably no) ground.
I tested the mounting bolt head to ground which was good, due to the rust around the mounting bolt hole in the ICM, I don't think that was a good ground either.
There are some star(ish) washers on the mounting bolts so I suppose those were supposed to create the ground. I should have sanded a bare spot on the ICM housing to test the continuity before I removed it. So all I know now is that there probably wasn't a good ground.
Since I still really don't know what caused the overheating of the ICM that I would prefer to start with a cheaper one. If it immediately fries after installing it, then I haven't lost as much, and I know to keep looking for a problem elsewhere.
If it works fine, then I would probably get a higher end ICM and replace the cheap one and keep the cheap one as a spare. I am not really worried about installation time and effort as it only took me about 15 minutes to get the old one out and most of that was trips to the tool box. If I had the right wrench in the fist place I could have done it in a couple of minutes.
I also worry about rewiring to fit the 4 pin units. I am not a electrical novice, but wrong wiring will probably fry the new unit and thus my expensive investment would be up in smoke.
I was planning on getting an inexpensive 5 pin ICM so I didn't have to do any rewiring either. But, perhaps I should get a 4 pin and rewire for the cheap one, so that one can get fried instead.
One more issue. I can get a cheap one today locally, the more expensive ones I have to order online and they will take up to 10 days to get here.
Thoughts?
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Experience is what you get, when you didn't get what you wanted. -Anon
Ballenxj wrote:
This seems to be a common problem? I wonder if maybe somebody should reverse engineer one and build a better one less prone to failure?
This seems to be a common problem? I wonder if maybe somebody should reverse engineer one and build a better one less prone to failure?
Griff thinks they have. The problem I see is that I only found one ICM that had any description of the product. They claim theirs is more heavy duty as they use larger wires and weld copper heat sinks to the components and do laser trimming (not sure what that does for them). The only other descriptions I saw was "chrome case," or "gold case."
So the only other indication of quality we have is the price. But that is not always a good indication.
Gonna go do that on mine, have some old pentium heat sinks around here somewhere....