Horn not working - air horn installation

I installed a Wolo 12v Air Horn in place of the stock horns, using the existing wiring and grounding the compressor to the chassis. It worked, but blew the 5A stock fuse. I ended up going up to a 20A fuse and everything was working great.

Then I got my interior detailed and after that, the horn stopped working. I have no idea if those things are connected though. The fuse had blown, so I replaced it. It worked briefly, then stopped working. The fuse is fine.

I'm thinking of replacing the relay as it's a cheap enough fix. But... can anyone tell me if I've wired it up incorrectly? I followed the instructions that came with the kit for the most part, but wanted to wire it up to work with the steering wheel rather than a new switch somewhere.

Any ideas?

 

Without knowing what you did it’s pretty hard to determine. Your just going to have to go back through your work and test everything to find the problem. Sorry if that’s little help.

 

Can you tell us how you currently have it wired?
I’d probably use the stock horn feed wire to power the new horn relay.

When you say “going up to a 20A fuse” what fuse is this?
The stock fuse in the truck? (I think it is a 10A)
Or the fuse supplied with the new horn?

 

I would use (as stated above) the stock wiring to power a Relay that then uses its own fused wiring from the battery to operate the horn compressor etc.

Battery >> Stock 10 Amp Horn Fuse >> Horn Relay >> Air Horn Relay Coil.

Battery >> Fuse recommended by Air Horn Mfg >> Air Horn Relay Contacts >> Air Horn Compressor.

 

You should never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, never, replace an OEM fuse with a higher amp rated fuse.

That horn came with a 30 amp relay. You should use it as Jimmy recommended.

 

This^^^^^^!!!!! Or post pics after the truck burns down.

 

Not uncommon on some cars as the factory isn’t rated for the new horns amp draw.

Confirm horn max amp draw and relay rating. It might be as simple as replacing a relay.

 

@skootx fuses have 2 jobs. First and most important is to protect the wires. Second, to protect the connected load. Fuses and wires are sized based on the load, in this case; your air horn.

A relay is nothing more than an electrically operated switch. The relay is rated to carry a higher current than the horn switch in the steering wheel. it is much easier to bring a wire rated for 2 amps up to the steering wheel than it is for a wire rated 30 amps.

Turning the relay on with the existing horn wiring is not an issue because the relay load is considerably less than the actual horn. Using the existing wiring to operate the new horn IS an issue because the existing wiring is not sized to carry that load along with everything else on that circuit. It could turn ugly...

As for how it should be wired... The numbers 30 85 86 87 and 87A are are common nomenclature on standard Bosch relays. Number's 85 and 86 are the coil. Applying 12 volts across these two terminals will operate the switch by energizing the relay. Terminals 30, 87 and 87A are the actual switch contacts. Common, normally open and normally closed respectively.

To visualize this switch take your left hand and make the letter V with your index and the middle finger. Your right index finger will bounce between the two legs of the V. Switch contacts are designated normally open or normally closed in their at rest position. Now going back to your fingers: your right index finger is terminal 30 now put it in the V and touch your index finger That is terminal 87A and they are connected when the relay is turned off. Energizing the relay pulls your right finger down to your left middle finger which is terminal 87 the normally open contact. Terminals 30 and 87 are the ones you'll use to apply power to the air horn compressor.

For the actual wiring.... Take the existing horn wire and connect it to terminal 86. Ground terminal 85. Now the relay will turn on when you push the horn button on the steering wheel.

Starting at the battery, use a wire as short as practical to feed a fuse. This wire is unprotected, so we want to keep it short and clear of anything that could damage the insulation and cause a short. The other side of the fuse will connect to either terminal 30 if you have a 4-pin relay or terminal 87 if you have a 5-pin relay. I generally do this so that terminal 87a is not energized when the relay is turned off. If you only have four terminals then it doesn't matter. The last terminal, to the compressor...

If the air horn came with a 20 amp fuse use 12 awg wire. 30 amp requires 10 awg.

Good luck.

 

I find it odd that he says it blew the "Stock 5 Amp Fuse". All the schematics I have shows it as being a 10 amp fuse for the horn circuit.
Sum Ting Wong...

 

Until we know how OP has it wired, all we can do is “guess”.

I hope he didn’t substitute any fuses.

 

He already said he changed some out for larger ones

 

Yeah, but he not did say what one.
If you go to the link in his post, you’ll see these directions.
I hope it was the fuse shown, and not some other fuse in the truck.

 

The way I read it was that he used the factory wiring to feed his new air horn compressor. And that he changed the fuse to a 20 amp to accommodate the existing wiring carrying all that extra current.

that's not the case.

Oh, btw Happy New Year everyone..

 

That’s how I read it to. Sounds like he might be replacing some wiring. Hopefully it didn’t cook anything to important.

 

Ayup

 

This ^ you most likely damaged a wire by using a higher amp fuse,which is a no no.