Keep it simple, check the horn fuse, if good remove horn relay & briefly connect the #86 & #30 (12V+ to horn), If horns blow then swap relay with Daytime running lights. Note the relay position when you remove them cause GM reverses some of the relays. If horn still doesn't work then its probably the horn switch on the air bag cover. $400+ repair.
The fuel pump relay for that vehicle should be located under the hood, on the firewall, on the passenger side.
There isn't a fuse for the horn. The horn instead uses a relay to function. The GM Parts Department specifies it is located underneath the driver's side panel where the accelleration and brake pedals are.
It is in the glove box. You will have to call the dealer after retrieving these codes they will be able to identify the exact one.
R134
definatly sending unit gm's are notorious for this
GM vehicles do not use inertia/reset switches.
its in the main manual. the fuse is in the eng compartment driverside plastic box next to inside of fender .in the box its towards back of the truck next to a relay .
If it is a newer GM, you should be able to put the key in the "On" position for 10 minutes and the relay will reset itself.
Location of knock sensor 1991 GM sierra 350 2500?
what size engine
Pay someone to do it.