Service Engine Light On Highway Cruising...

[TwitchZ28]

On the 91 I just bought the SEL will come on after you've been cruising with cruise control on for a little while and it's not there when you turn the truck back on. It doesn't affect anything...it just comes on. My 93 s10 blazer used to do the same thing. I have no idea what it could be. I know I never got a code off my blazer when I would check it. I will check the silverado and see if i can pull a code or not. I doubt i'll get one.

Anyone else have this small issue?

 

[DRAGGIN95]

I owned a 90 model that did the same thing, it was setting an EGR code at highway speed only, I changed the EGR valve and the egr sol. to no avail. Finally I pulled the intake off of the truck and the EGR passage in the intake was completely blocked off with carbon, I cleaned it and problem solved!

 

[1997chevydriver]

I had it on my 94 and it was just the egr system setting a code

 

[1997chevydriver]

Damn you draggin you beat me to it

 

[DRAGGIN95]

Yeah I'm sneaky like that!

 

[BlackBeauty]

My dads '02 Denali has a random cylinder misfire, that only happens when cruising down the highway, but once you get off the highway and cruise around town it goes out

 

[DRAGGIN95]

LS motor's are very prone because of their PCV and crankcase breather system's to get a lot of carbon built up in the intake, TB, and also have dirty injector's and it can make them miss and run poorly, I have cleaned several of them that were absolutely full of carbon!

 

[TwitchZ28]

Well it doesn't misfire or anything it drives perfect...just has the light come on. Only if you use cruise too...if you don't use cruise it stays off.

 

[DRAGGIN95]

I suggest pulling the code to see what it is first.

 

[jrp12357]

Mine does that same thing, Mines a code 32 which is Egr valve I believe.