Service Engine soon light on, EGR code problem. Need to turn light off.

[truckdoctor]

I have a 87 GMC 4X4 with the fuel injection that the service engine soon light just came on. I took a tool I have and got the code from the computer indicating the EGR malfunction. This isn't my question (unless you have had the same code and found out what the problem was, I'm sure mine will be different because that's just the way my luck is). I'm wondering because I couldn't cancel the service engine soon light with my tool, what I'd like to know is if a fuse such as the radio fuse can be removed for a little bit will turn the light off without disconnecting the battery itself? If a fuse can be removed to do this, which one is it?

I just installed the 87 engine, wiring, and computer in my 84 truck. The engine has run great now for about 500 miles, but this is the first indication of anything out of the ordinary. I'm going to check the vacuum hoses and connections to the EGR itself, but something tells me I'll end up replacing the EGR. I remember having to put a vacuum guage on a EGR in my 87 Chevy Blazer years ago to check the EGR itself out. From what I do remember about the whole thing was if you pulled vacuum on the EGR with the vacuum pump and the EGR lost vacuum, it needed replacing.

I'll do this tomorrow afternoon, but if you know of this light deal so I can turn it off without disconnecting the battery I would appreciate it.

Thanks.

 

[Captkaos]

You have to remove all power to the truck, so disconnecting it the only way.  Why is this a big deal?

[VileZambonie]

You can remove the ECM fuse if you want but disconnecting the battery will also clear the DTC.

As far as testing the EGR itself, apply vacuum to the EGR valve with the truck running it should make the truck stumble and die. If that checks out OK verify you have vacuum to the EGR solenoid. There should be no vacuum to the EGR valve until the solenoid is energized. You can energize the solenoid yourself to manually test it.