Engine Stalling when warmed up! Code 42

MORID

MEMBER
1989 CHEVROLET TRUCK
V8
4WD
AUTOMATIC
220,000 MILES

I recently purchased this truck and the engine was replaced with an engine that has 67K miles. The engine runs great until 15-20 miles down the road. When it gets nice and warm the engine sporatically loses power and turns on the Check Engine light. If I slow down the truck shuts off completely. It will refire but will shut back off until cooled down. I have changed the ignition coil, Wires, plugs, cap. I am completely lost on what other than the ECM it could be! The trouble code that is registering is 42. Any help would be appreciated!

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

Hi,

A code 42 is related to the electronic spark timing (EST) system. The code can be the result of a faulty ignition control module, a short to power or ground, or a faulty ECM.

If you look below, I attached the diagnostics related to the code. It will require wire testing to confirm where the problem is coming from. I would like to add that in most cases (not all) the problem is usually a faulty ignition control module.

Here is a link that you may find helpful when testing wiring:

https://www.2carpros.com/articles/how-to-check-wiring

I hope this helps. Let me know if you have other questions.

Take care,

Joe

See pics below.

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