2010 Avalanche LTZ Horn Problem

[MACGYVER24]

My horn doesn't work on my 2010 chevy avalanche

Tested - continuity through clock spring, both tan wires Lft/Rgt pass through to the firewall, I looked at schematic from Mitchell, the tan wire goes to BCM and to fuse box. I guess there's a pcb relay in the fuse box ?

No horn sound with keyfob

12v batt pwr to #29 fuse makes the horns work

I triggered horn relay in my scanner, no horn sound

My only guess is the relay in the fusebox has failed. Do I need to test for continuity at BCM too

Any suggestions ?


Thank you for your time

 

[CarMech1969]

Try swapping out the horn relay with another relay of the same type in the fuse box, and see what happens.
For example, I'm assuming that the truck runs and drives - so clearly the fuel pump relay works.
Put the fuel pump relay in place of the horn relay (if it is physically interchangeable)...and if you have the problem still, you know the relay is not the issue.

 

[MACGYVER24]

Try swapping out the horn relay with another relay of the same type in the fuse box, and see what happens.
For example, I'm assuming that the truck runs and drives - so clearly the fuel pump relay works.
Put the fuel pump relay in place of the horn relay (if it is physically interchangeable)...and if you have the problem still, you know the relay is not the issue.

?

Try swapping out the horn relay with another relay of the same type in the fuse box, and see what happens.
For example, I'm assuming that the truck runs and drives - so clearly the fuel pump relay works.
Put the fuel pump relay in place of the horn relay (if it is physically interchangeable)...and if you have the problem still, you know the relay is not the issue.

I believe the relay is a pcb in the fuse block, there's no listing in fuse box cover for a horn relay and the schematic lists it as a pcb relay

 

[Capt.Crunch]

Have you checked the fuses inside the driver side of the dash, mine wasn't working or the power outlets on the console and it was a 10 amp fuse on the inside of the cab.

 

[MACGYVER24]

Have you checked the fuses inside the driver side of the dash, mine wasn't working or the power outlets on the console and it was a 10 amp fuse on the inside of the cab.

I checked all fuses inside and out but I'll give her another look JIC, thanks for the info, maybe I missed a fuse

 

[CarMech1969]

?


I believe the relay is a pcb in the fuse block, there's no listing in fuse box cover for a horn relay and the schematic lists it as a pcb relay

What about this horn relay in the diagram you provided, that appears to be outside the fuse block?

 

[MACGYVER24]

What about this horn relay in the diagram you provided, that appears to be outside the fuse block?

View attachment 234278

Mitchell/Alldata has no listing for an isolated relay, not tech notes, the schematic is listed for multiple trucks so I'm assuming instead of making multiple schematics they made one with all the possible options

Called the dealer, microfiche doesn't show a isolated relay for the 2010 LTZ avalanche.

I'll probably install a taped fuse with 30a relay, trip the relay off the tan wire to power fuse #29 (horn fuse) I'll pull 12v at the fuse block.

*Bypass OEM PCB Relay*

(Any 5 pin 30 amp Relay from autozone, Amazon, etc) wiring ---> 86/30 pin to 12v, 85 pin to the tan wire (- neg trigger), 87 pin 12v out to the fuse tap at fuse #29 to trigger the horns

I moved to Texas from another state that doesn't have inspections. Train horns, race muffler and 15% tint are not acceptable to pass a vehicle inspection [bang head here] I never fixed the stock horn because I didn't have to.

I work at a family owned Auto Recycling company now, I'll just wait till we get a compatible fuse block from an escalade or other compatible vehicle in the future

Ret. ASE Nissan Tech, I don't know everything, I can be wrong as nobody's perfect, 12v is my Playground/Disneyland