I'm having EGR troubles.

My solenoid is never getting grounded, which means the EGR is running all the time, making it run rough in the morning and surging on the highway.

Grounding it manually fixes the problem, so I checked at the ECM and it's never grounding the pin... resistance is infinite all the time, key on engine off, with and without the ALDL pin grounded. The ECM thinks that it is activating the solenoid, it's giving me changing EGR duty cycles.

But! I'm also getting code 36 (MAF burnoff relay) and I'm wondering if that means there is a short somewhere that has damaged the ECM internals. Any ideas on how I can further test things?

I'm worried because I'm doing a 165 ecm to 730 swap but I don't want to fry the new ecm that I'm putting in.

Thanks,
Alex

PS. Do I really have to get the vacuum source for the EGR from the throttle body? Right now it runs much better this way, but it would be much neater to take the vacuum from the port right beside the solenoid where the cruise control line used to go. The vacuum should be off at idle anyway, so I don't see why it matters. Pros/cons?

 

If the EGR solenoid is not getting a ground through th eECM, it is NOT operating all the time. Just the opposite is true. If the EGR valve is opening with the EGR solenoid de-energized, the vacuum routing to the EGR valve pilot is suspect.

As for your initial question, ECM failures occur from overvoltage, shorted outputs, and transients.