Ford Truck Enthusiasts Forums - How do you know if your ignition control module is bad?

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- 1973 - 1979 F-100 & Larger F-Series Trucks (https://www.ford-trucks.com/forums/forum38/)

- - How do you know if your ignition control module is bad? (https://www.ford-trucks.com/forums/878326-how-do-you-know-if-your-ignition-control-module-is-bad.html)

Quote:

Originally Posted by columbia1spring (Post 17418930)

I now feel like a true f100 truck owner!
Started my 74 backed it out and enjoyed a few hours of cleaning, went to restart and it was super slow cranking. The new battery, was fully charged and all connections were solid. Got out my spare ignition control module, quick swap and it started instantly! Need to replace the spare asap!

Quote:

Originally Posted by NumberDummy (Post 7862182)

Yes, the engine will crank, but whether it cranks slow or fast has nothing to do with the ignition module.

It may act that way due to a fully charged or low battery.

The speed of cranking has no relationship to the ICM.

Well as long as this thread has been bumped I will share how I knew my ICM was bad.

I had just purchased my "78" F-250 several weeks prior and one day it just stalled out while driving it. This ended up happening several times over a few weeks and I had no clue as to what was wrong. It always started back up after a few minutes.

One day I started the truck and my neighbor called me because he heard the truck start up (nice dual exhaust) and he needed to ask me something. He had been a mechanic for the city and was very sharp so I described my problem to him on the phone and he told me to go to Autozone and buy a new ICM. I did and came home and installed it and the truck never stalled out again.

That's how I knew my ICM was bad and it only cost $20 or so.