91 Suburban 2500 Horn issues

[jeremy.farlow]

Fuse blows immediately... obviously a dead short somewhere, but I’ve traced the circuit and there’s nothing obvious. Factory service manual says check the horn relay and turn signal switch... problem is I the fuse blows IMMEDIATELY, so I’m worried about putting a jumper wire to help diagnose.

Anyone got any ideas?

I’m trying to not just throw parts at the thing.



Be safe and stay healthy



Jeremy

[bd]

Try this first.  Unplug the horn(s) and install a new fuse.  If the fuse doesn't pop, plug in the horn(s).  If the fuse pops, replace the horn(s).  If the fuse doesn't pop, the fault is intermittent.  To diagnose, temporarily replace the fuse with a 15- to 20-amp auto reset circuit breaker and buzzer connected in parallel.  Whenever the circuit breaker opens the buzzer will sound until the breaker resets, cycling ad infinitum.  You can troubleshoot the circuit this way w/o investing a fortune and the best years of your life replacing blown fuses.

[jeremy.farlow]

Already done the unplug everything in the related circuit. Chased the wires. Obviously I’ve got a serious dead-short I’m missing somewhere.

Thanks for the circuit breaker idea... reason I asked here is for tips like that and also specific knowledge.

Thanks BD, I’ll be on the hunt for a breaker tomorrow morning.

Now, anyone else? Bueller? Does some stupid failure elsewhere cause a massive dead short?

Factory service manual says check circuit, check horn relay, check turn signal switch?!? problem is until I jump the fuse however I do, I can’t use a test light or follow the factory recommendations.

And fuses are getting expensive!


Be safe and stay healthy




Jeremy

[Mike81K10]

Has any part of the circuit been messed with or the CB panel. If not I would start by checking the wiring at the steering column with a meter to the CB and then to the steering wheel horn itself.

[bd]

Remove the cigar lighter element from its socket and/or unplug the orange wire from the backside of the lighter socket, then recheck for a blowing fuse.  Otherwise, trace the orange wire running between the HORN fuse, the horn relay, and the cigar lighter.  FYI -the pertaining horn wiring in the steering column is on the ground side of the relay control circuit so that can be ruled out.

[bd]

Another potential problem spot exists where the overhead dome lamp wiring passes rearward under the left door sill plate before ascending the B pillar.  The orange B+ feed to the lamps (fed by the same 20-amp fuse shared by the horn and cigar lighter) can be compromised by physical damage due to pinching to ground by the sill plates or perforation by a sill plate screw.

[jeremy.farlow]

Bd for the win. Pinched wire in the dome light circuit. Fixed now, horn works, dome light doesn’t work as much as it didn’t work before. I’d rather have the horn.




Be safe and stay healthy


Jeremy