Need help with code 42

I need any help with a code 42 in the ecm. I start my truck in the morning and go to work and it is fine, when i go to leave and start it the service engine light comes on, as soon as i shut it off and restart it is fine again. I have a ecm reader and the code 42 is what comes up any suggestions on how to fix.

Thanks

Code 42 is the ignition module. More specifically "The EST signal did not change when the ECM applied bypass voltage to the ignition module." This is probably related to the ticking sound coming from your dist. Might be time to pull the dist and see what is worn out.

//2000CAYukon

What did you find out? Did you get the problem fixed? Mine is doing the exact same thing.