ICM question

Tiny
BILL STRATHERN
  • MEMBER
  • 1993 OLDSMOBILE CIERA
  • 3.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
I have checked wires off ICM and crank sensor all looks good. Majority of my problems seem to have occurred after I had removed the aluminum plate under the ICM. There is corrosion here. My new coils read the same resistance as old ones but I do see cracks at bolt down area and black marks on primary tower plastic about midway up.
Sunday, August 12th, 2018 AT 10:36 AM

8 Replies

Tiny
BILL STRATHERN
  • MEMBER
  • 8 POSTS
  • 1993 OLDSMOBILE CIERA
  • 3.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
I have fried three ICM's in last six months. The last one I never got started. I have power in, crank sensor is new. What is frying it out? Can bad coils do this? All three coils read no resistance at primary and 5600 at secondary. Does the ICM ground on aluminum case? Saw something about aluminum oxide being a problem. Please give me something to fix before I install new ICM again. Thanks
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Sunday, August 12th, 2018 AT 11:20 AM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

I always replace the ICM and the coils as an assembly. A voltage surge from one of the coils will cause the module to fail.

There is a ground wire on the module where it mounts. Make sure it is clean and tight.

Also, when you mount the ICM on the bracket, did you use the grease on the bottom? That is critical to help dissipate heat.

Roy
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Sunday, August 12th, 2018 AT 3:45 PM
Tiny
BILL STRATHERN
  • MEMBER
  • 8 POSTS
I do not see a ground wire on this bracket. Should be to one of the three square head bolts that hold it to main bracket? And no I did not grease it. Electric grease? So should I clean corrosion off whole ICM bracket and main bracket or just worry about ground wire? Whole back plate is grounded? Thanks for help and insight.
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Monday, August 13th, 2018 AT 2:44 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
The bracket is the ground. Clean the area completely. Use dielectric grease as shown.

Roy
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+1
Monday, August 13th, 2018 AT 2:48 PM
Tiny
BILL STRATHERN
  • MEMBER
  • 8 POSTS
You do not happen to know the size of the bolts that hold coils to ICM and bracket? Cannot find the originals.
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Tuesday, August 14th, 2018 AT 5:16 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
They are 7 mm bolts that hold the coils. Either that or 5.5 mm. Been a while since I did them.

The bracket is 13mm.

Roy
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Tuesday, August 14th, 2018 AT 5:58 PM
Tiny
BILL STRATHERN
  • MEMBER
  • 8 POSTS
Thanks for your help. Got it running.
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Thursday, August 16th, 2018 AT 6:33 PM
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
You are welcome!
Thanks for using 2CarPros.
Danny-
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Thursday, August 16th, 2018 AT 7:05 PM

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