ICM longevity

[Abrooks]

After my 4th Ignition control module (3rd relocated one) crapped the bed at the midddy, I'm toying with ideas for keeping it alive a bit longer. Due to the symptoms it was exhibiting as it was dying, I'm pretty certain that it's failure was heat induced. While I considered doing the GM ICM retrofit, I thought I'd try this one last time. I picked up from radio shack a 1.5" square heat sink and fan for a pentium CPU. It stands about 3" high with the fan and the fan is 12VDC. On the relocation bracket, if one were to shift the components around a bit, theres room to fit the ICM on the front side of the bracket, and the support for the harness can go on the side, thereby leaving room on the back of the bracket for the heatsink to mount. Only trick will be figuring out how to power the fan, I'm thinking of hooking it up to the positive and negative sides of the coil.

What thoughts do y'all have?

Tony

[Mike Hippert]

Hmmm, how many miles between ICMs? Yours seem to be dieing fast.

For fan power yo could run wires right to the alt as it is only a foot ot 2 away.

[rover4x4]

I thought there was some sort of relocation kit for this? Maybe I am thinking about another part of the ignition/ecu kinda stuff?

[Abrooks]

Mike, they're lasting 5-10K miles, don't know if they're dying so rapidly due to heat (my suspiscion) or something else (any ideas?). Good thought on the alternator, though if I could wire it up with a smaller run to the coil or some other switched supply, I think it'd be cleaner. So the question is, how and where do I best hook it up? Theres a + and a - wire, no ground . . .

Philip, this is WITH the relocation kit!!! mercifully the module itself is only $55 vs. $250 for the whole kit. It is the bracket that comes in the relocation kit that I'm adapting to with the heatsink and fan. I may also try to reposistion the bracket so that it's a bit closer to the wing vent for more heat displacement.

[Mike Hippert]

Well to get it right off the ICM I would use one of the bolts holding the ICM on for the ground, as for + I normal just pull out my DVM (Digital Volt Meter) and measure between ground and the pins on the bottom until I find 12 VDC, take it as a good reason to buy a DVM, Sears has one for $40, it even has a temp probe that may come in handy for other things.

I am still puzzled as to why they die so fast, but I am often puzzled by the under hood temps of other peoples 90s. When on the trail my temp gauge is always telling me my engine is running on the warm side (190*), but if I put my hand on my wing top it is cool, but often I'll lean on someone else's wing top and it will be burning hot and there temp gauge will only read 1/2 way or 180*. So my question to you is how hot is the top of your wing?

[Abrooks]

Have volt/ohm meter and will check tonight, though its more fun to pretend to work and try to figure this out now! Does the coil energize when the key is turned to accessory and when does it de-energize?

Wingtops don't hot, though underhood it does get warm. Engine temp is static at 190, but who knows what the temps get to underhood. I'm going to take apart the dead module to see if I can find how and where it failed.

[Mike Hippert]

Yes more fun at work :)! Mine comes on and off with the key. Do you buy your ICMs from the same place every time? Are they da Rover ones? I have the original as a spare and it looks different then the replacement one on my 90 right now. My PO had it replaced when the engine was stalling alot, he had a bunch of other stuff replaced also, then they put in a new fuel filter and it ran great. When he sold me the 90 he gave me all the parts they replaced as backups.

[Abrooks]

Nice to have all of those spares after somebody else paid to play the parts replacement game! Lets see, the modules have come from the dealer, Rovers North and Europarts, just ordered this 3 pin module from NE Rover parts, and yup, they're the rover ones. New module should arrive tomorrow, the special glue stuff for the heat sink should arrive Thursday and I got the heatsink at Radio Shack yesterday. Hopefully by the weekend I'll have this figured out.

[Mike Hippert]

Hmmm, that special glue stuff isn't thermo compound or past? They should also sell it at Radio shack.

Yeah kinda nice, but I haven't had to use any of them but have had to use a lot of other parts. Take pics of your setup when your done.

[jaherring]

You could always relocate it into the passenger compartment... just splice in a wiring extention.... I'm not sure those PC fans are very good in damp environments. They are certainly never expected to be exposed to that...

[Abrooks]

They didn't have the glue stuff, I wound up ordering something called "white lightning" or something, one of my computer geek friends (no offense to anyone) said it's the stuff to use.

Relocating it is an option, but I'd like to keep it as consolidated as possible. I suppose I could put it next to the main computer though and cover it with one of the panels when they come out with more of them (hint hint)

[jaherring]

That's just one type of thermal paste/grease. To be competely honest, what you are cooling gets nowhere *near* the temperature of an operating CPU in a PC. And I don't think that a PC fan will last very long exposed to the elements - IMHO.

Signed,
Computer geek

[evilfij]

Replace your coil. Also check for excessive dwell angles and report back.

[Abrooks]

Ron, coil has about 3K miles on it and is a bosch. Will check dwell this weekend when I replace it all, though it was fine for the last replacement . . .

[Abrooks]

Just to bring this thread to a close, the truck is up and running again . . . sorta. Got the new ICM from NE rover parts and removed the bracket. What I wound up doing was mounting the module on the other side of the bracket (away from the motor), drilled out the rivet and removed the bracket that holds the harness and grounds the module. Used something called "arctic silver" heat sink adhesive and mounted the heatsink on the bracket facing the motor. Cut down new screws for the ICM so that they didn't protrude past the plate (I think the threading is 4 BSF if I remember correctly). Put it all back together and she's working fine. Haven't figured out how to wire the fan yet, but will this weekend. Pendy came through and suggested that the alternator is causing the cooked modules, so I'll play around with that.