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Bill, Chevy Technician
Category: Chevy
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Experience:  GM Certified Master Technician
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What are the symptoms of a bad / or going bad ignition contr

Resolved Question:

What are the symptoms of a bad / or going bad ignition control module [ ICM ] ?

My car is a 2000 Chevy Impala LS. With a 3.8L V6 / VIN K engine.

Odometer: [ 168000 KM ].

My email address: [email protected]

Please reply soon.

Thank you.


Submitted: 6 years ago via AllDataDIY.
Category: Chevy
Expert:  Bill replied 6 years ago.
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Expert:  Bill replied 6 years ago.
Hello, Generally an ignition module failure, which is actually rare on the 3800) will cause a cut and dry loss of spark therefore the ability to run. More often than not, it is the terminals at the icm connector that are the issue. You've replaced several parts however you didn't mention the symptoms you are chasing. Some additional info would be helpful. Thanks you.
Customer: replied 6 years ago.

(2010 / 09 / 16 )


Hello Bill:


Upon starting up my car, I would sometimes experience a slight rough idling, from the engine; while waiting 1 or 2 minutes, before driving off.


While driving the car, I do not experience any rough idling. The car performs normally and well.


I usually get preventive maintenance done on my car, frequently. I do not slack off on this.


Prior to installing the new ignition coils. The ICM was removed and cleaned with silicone lube spray. The connector was also cleaned with silicone lube spray. The connector wires, all appeared to be well and in tact. I applied some di-electric grease onto both male and female connectors there. I also applied some di-electric grease, at the connecting points, where the ignition coils plugs onto the ICM. I applied some di-electric grease into both booths ends, on each of the six spark plug wires.


Thank you.






Expert:  Bill replied 6 years ago.
First thing I would check is the fuel pressure regulator on top of the fuel rail. It has a vacuum hose going to it. Sometimes the diaphram breaks internally and fuel can leak through the vacuum hose into the intake plenum. This will cause an extended crank after sitting a while and a rough idle for a period. Pull the vacuum hose off and smell for fuel. You can also start the engine with this hose off and smell and also look for some fuel coming out of it. I seriously doubt you have an ignition issue. That will show up more when warm and under load such as light accel. Hope this info is helpful !
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