icm burnout
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Junior Member
Joined: Oct 2020
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icm burnout
Hi all,
replaced icm as well as several other components to get car running decent about six months ago. recently, car acted funny and stalled; barely got it started and limped it home. replaced icm and ran like a charm for a week, then again, tach goes haywire and engine stalls. next day, starts right up and runs okay for a while, then craps out again. replaced both times with budget parts and generous amount of thermal paste, but afraid to put in $80 component if its just gonna burn out again. could something else be causing this?
thanks in advance
replaced icm as well as several other components to get car running decent about six months ago. recently, car acted funny and stalled; barely got it started and limped it home. replaced icm and ran like a charm for a week, then again, tach goes haywire and engine stalls. next day, starts right up and runs okay for a while, then craps out again. replaced both times with budget parts and generous amount of thermal paste, but afraid to put in $80 component if its just gonna burn out again. could something else be causing this?
thanks in advance
Supreme Member
Joined: Feb 2021
Posts: 1,209
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From: WA
Car: 1989 IROC-Z
Engine: L98 350 TPI
Transmission: 700R4
Axle/Gears: BW 9 Bolt / 2.77 Posi
Re: icm burnout
There is such a thing as too much thermal paste, go moderate with it. Put an AC Delco unit in and see if it fries. You can't be afraid of $80 fixes, cars are expensive.
Joined: Oct 2013
Posts: 2,612
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From: Louisville, KY
Car: 1983 Z28
Engine: 385 Fastburn
Transmission: T-5
Axle/Gears: BorgWarner 9-bolt posi, 3.27 gears
Re: icm burnout
A bad coil can fry ICM's. Also a "hot" coil (MSD, ACCEL, etc.). Match brands between your coil and ICM (AC Delco is what I recommend) and you should be fine.
I was going through ICM's every few months, enough so that I kept a handful in the trunk. I finally replaced my MSD coil (which tested fine) with a stock AC Delco unit and haven't had issues since.
As extra insurance I added a finned aluminum heat sink to the bottom of the distributor, but that's probably overkill.
I was going through ICM's every few months, enough so that I kept a handful in the trunk. I finally replaced my MSD coil (which tested fine) with a stock AC Delco unit and haven't had issues since.
As extra insurance I added a finned aluminum heat sink to the bottom of the distributor, but that's probably overkill.
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From: Canada
Car: '18 Chev Camaro SS 1LE
Engine: LT1 6.2L
Transmission: T56
Axle/Gears: 3.91
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From: Canada
Car: '18 Chev Camaro SS 1LE
Engine: LT1 6.2L
Transmission: T56
Axle/Gears: 3.91
Thread Starter
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Joined: Oct 2020
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Re: icm burnout
Thank you, Gentlemen. I shall take your advice, but in the meantime I was able to pull a GM stamped OEM ICM from a '91 bird that was dragged into the local Pic-a-Part a couple weeks ago. Even though ity's prolly ~30ish years old there is definitely a visible difference in manufacturing quality. Gave it a shakedown today with about 100 city miles in 12 hours of deliveries and purred all day. And the price was right, at $FREE.99, so we'll see. Thanks again for the input.
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Re: icm burnout
Quick question
GM GENUINE D1984A
or
GM GENUINE D1943A
W/O HEI (High Energy Ignition)
Whats the difference (other than price) and which should I use ? Both parts say they fit my vehicle.
GM GENUINE D1984A
or
GM GENUINE D1943A
W/O HEI (High Energy Ignition)
Whats the difference (other than price) and which should I use ? Both parts say they fit my vehicle.
Joined: Oct 2013
Posts: 2,612
Likes: 157
From: Louisville, KY
Car: 1983 Z28
Engine: 385 Fastburn
Transmission: T-5
Axle/Gears: BorgWarner 9-bolt posi, 3.27 gears
Re: icm burnout
I believe the first one as HEI is the name of the whole system that the ICM resides in.
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Re: icm burnout
The other module, D1943A (also GM 19179578), appears to be a generic module for 1986-1997 4-cylinder, V6, and general V8 engines like truck, bus, sedan, etc. It might work but isn't specified. That may also partially explain why the "generic" replacement modules seem to have a short life if they are mis-applied.
Supreme Member
Joined: Feb 2021
Posts: 1,209
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From: WA
Car: 1989 IROC-Z
Engine: L98 350 TPI
Transmission: 700R4
Axle/Gears: BW 9 Bolt / 2.77 Posi
Re: icm burnout
https://www.thirdgen.org/forums/diy-...ml#post3775917
https://www.thirdgen.org/forums/diy-...ml#post3924372
http://www.gearhead-efi.com/Fuel-Inj...odule-failure&
ICM stamped '369' (AC Delco D1943A, GM 19179578): First used on the 1985-1993 Chevrolet Caprice with the 9C1 RPO Police option. This ICM does not retard timing starting at 3500 RPM, but provides 2 degrees additional advance from 4,000 to 5,000 RPM and a total of 6 degrees additional advance above 5000 RPM.
GM replaced the "048" ICM with the "369" ICM. The replacement may not have "369" printed on it. The "048" was discontinued so GM felt like there was no need to differentiate between the two. If the AC Delco D1943A module does not have "369" printed on it, look for the GM part number 19179578 burned on the edge of the module. The 19179578 8-pin ICM was originally for the 9C1 Police Option in a Caprice. In 1989 GM made the AC Delco D1943A ICM (19179578) as the service replacement for all V6/V8 models through 1995
GM replaced the "048" ICM with the "369" ICM. The replacement may not have "369" printed on it. The "048" was discontinued so GM felt like there was no need to differentiate between the two. If the AC Delco D1943A module does not have "369" printed on it, look for the GM part number 19179578 burned on the edge of the module. The 19179578 8-pin ICM was originally for the 9C1 Police Option in a Caprice. In 1989 GM made the AC Delco D1943A ICM (19179578) as the service replacement for all V6/V8 models through 1995
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From: 212 is up in this Bit@#
Car: Resto-Mod 1987 IROC-Z Clone
Engine: Alky fed L92 Vortec Twin-Turbo 6.8L
Transmission: My own built/ design 4L80M
Axle/Gears: Custom 12 bolt (4.10:1)
Re: icm burnout
What product was used as Thermal Paste?
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Re: icm burnout
Repeat module failures? Suspect the ignition coil. Ignition coils must pass ohmmeter tests of primary and secondary resistance, and have no continuity to ground, AND they must reliably fire a spark-tester calibrated for HEI. They can pass the resistance tests and STILL BE DEFECTIVE.
This is a spark tester that DOES NOT have a dumbass light-bulb inside. It has an actual spark gap that the voltage has to jump. And it is a bigger gap than used with points or ballast-resistor electronic ignitions use.
For example:
This is a spark tester that DOES NOT have a dumbass light-bulb inside. It has an actual spark gap that the voltage has to jump. And it is a bigger gap than used with points or ballast-resistor electronic ignitions use.
For example:
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