I just replaced my stock horn with 2 late 50's auto-lite (VErY LOUD) horns but there is a problem. I keep blowing fuzes and it will not sustain a blast, just short beeps. The stock horn used 2 wires and did not require the horn be bolted to chassis to work. My new old horns only have hookup for 1 wire and get ground from chassis mount. Any ideas?

 

The stock horn uses a ground wire (Blk) which is connected to ground hence it does not need to bolted to the chassis, and the Dk GRN from the horn goes to a relay and fuse. The horn button connects to the BCM which activated the horn. It sounds like your new horns are pulling more than the 10A fuse can handle. I would wire up a separate circuit for the new horns with another dash mount switch as others have done, or add another relay to the circuit to supply power to your new horns (you would need to see a wire diagram to know where to install it). Not knowing how much current the OEM relay can handle, I would opt for a separate circuit. Other option is get a horn that draws less than 10A.

 

YES the new [older] horns draw a little more but you are now drawing with two horns. I put in a 15amp fuse over two years ago all works with no fuse blowing.

 

Were the 50's horns from a 6 volt car?

 

1955 for Chevy began 12 volt systems. Prior was still 6 V

I would like to add another horn w/original horn (but different tone) to my ride..

 

I dont know if the horns are 12 or 6 volt. The guy in Auburn didnt know if they were GM or what year. It was marked Auto-lite HW3. My 54 Buick was 12 volt and had osme monster horns.

 

more info on my horn problem, the current horn relay is a 20 amp 14 volt. 3 questions
1. can that be supersized?
2. supposed to be a 10 amp fuze, currently using a 25. Is that going to booger something up?
3. anyone know what amperage a late 50's 12 volt pair of horns is or how to tell? A google search on auto-lite horns produced nothing usefull

 

All calculations and engineering can be thrown out the door as a horn only operates for a short period of time. So my intuition says the relay will last for sometime, if not replace it with another identical one. The vehicle's wire size I'll bet is a bit small, but then again the horn does not operate all the time to heat up. Just checked the FSM, the wire size is .5MM.

All in all the advise in post #2 above about designing your own separate circuit is the only way to correctly do this if you use your horn a lot. Only problem I have with his post is the BCM is connected in parallel so it can activate the horn for alarm purposes. The BCM does not activate the horn when the steering wheel button is pressed. Source: 2009 FSM.

 

Thanks all for all the great ideas. to answer snow white, the relay is dtamped on the top with the info.
I went to oreileys auto parts and actually found a fella that knew his stuff about electrical. He set me up with a 30 amp relay which i fed fron the engine compartment battery terminal. I put a fuze link in line between the battery terminal and the new relay and put in a 30 amp fuze. I put a10 amp fuze back in position 60 for the horn. I basically followed the instructions on the back of the relay pack for the rest of the wiring and all seems to work. I let you know if anything jickey happens.

 

2 older GM horns should draw approx 6 amps combined. & GM Horns are Delco-Remy brand.