does anyone know what the relay that is on the outside of the under hood relay center is for in a 97 chevy c3500? it is hanging on the outside of the box. the wires for it are short and look as if they come from the computer. i am trying to figure out what the red wire coming from that relay goes to.

what engine do you have?
i dont see anything in my service manual for a 98...should be the same
might it be an alarm relay? outside/next to the underhood fuse block

i would guess 454 since his prifile says that.
also mine has it too but not sure what it is for.

its grey right?

yes its a 454 sorry i forgot that. it is grey. not sure what it is myself. cant find it anywhere either...

Does it have, or had an aftermarket alarm? That would be my guess.

this would be a factory relay. its a grey color and is mounted on the side of the underhood fuse box

Yeah it's factory, 100% sure. I can't tell you what it is but I can tell you that it's on both my '98 and '96 with 7.4's, and is NOT on a '95 4.3, '97 5.7, or '98 5.7...

The two I have with it, one is full power everything w/automatic, other is stripped down bare bones crank windows and standard, so it's nothing related to transmission or power accessories. Most likely something to do with engine controls on the 7.4.

Richard

I think its 4 the external fan in front of the radiator both my big blocks hav it i check tomorrow