My son's Silverado won't fear the modules at the garage for the emissions test. We did all the go but a 100 miles on it thing. PCU or wire ????

 

Check your cigarette lighter fuse

 

does the scantool power up?

 

Yes our hand held scanner reads. And the OBDII fuse is good.

 

so it powers up but doesn't read the ECM? Do you have access to any other modules or a different scanner?

 

Our hand held scanner reads but when I take it to the garage for emissions inspection it doesn't read the modules it needs for the test. I guess the ECU is not storing them

 

I don't really understand what you're getting at I guess. My guess is you need to try a higher end scanner

 

I'm having a similar problem with my '04 Silverado LT 5.3L. The I/M monitors will reset after reading with a code scanner. Someone suggested that the nonvolatile memory isn't retaining the information for the I/M monitors. Has anyone heard of this?

 

Update:
It turns out that the ECM was bad