[foxgapLeMans]

All, I just got this 2004 Silverado 4.8 auto truck and am trying to get it thru emissions here in PA. What I have figured out is that every time I turn the truck off it wipes out the monitors for all the emissions stuff. To try to get past this on Monday I am taking it for a 50 mile drive at 55MPH to set the monitors again and not shut it off to get thru emissions and get a sticker on it.

My question is, what should I do after the truck passes and I want to get a real fix for this problem ?

The one nice thing about this thing is right now I may never get a check engine light set but every year I am going t have to do the 50 mile 55 MPH trip on the way to the inspection shop.
Thanks, Mark

[george kujanski]

There may be a separate battery wire that maintains the short term memory, like in a car radio. If so, it may be a bad connection there. Just speculating tho.

George

[foxgapLeMans]

Thanks George, I never gave that a thought. All my old trucks have been OBD1, so OBD2 is something of a new animal for me.

[jerry455]

Find a manual and see where all of the power is for the PCM. Maybe one is nonfunctional.

[foxgapLeMans]

I'm sure I can find something online for a wireing schematic, after that we are going to start checking the wireing and most important the grounds to the PCM. I'm reading that an aftermarket part in the fuel system may cause the problem also.