The horn relay on the 1993 GMC Sierra is located on the fuse box. The horn relay is a rectangular shaped plug next to two larger round plugs.
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there is an access panel in the back of the glove box.
under hood in front of radiator
check your horn fuse not sure why but they are interconnected
The fuel pump relay on a 92 gmc 1500 is located on the passenger side of the firewall behind a black plastic cover.
should be located in underhood fuse/relay center, refer to diagram on inside of plastic cover to determine which one
wiring diagram for GMC 2500?
vin plate
If you open the hood. Facing the engine it is on the left mounted to the cab. THere should be a Black cover with diffrent words on it.
Next to the flux capaciter, in models 80-88 Ninety and up it's under the gas tank.
where is the fuel pump fuse or relay on 2005 duramax diesel