The Stovebolt Site Forums The Shop Area The Electrical Bay 1949 3100 HORN

I am rewireing my 49 3100 and found a horn relay mounted on the fire wall, but the replacement wire harness wires the horn direct. It appears that the horn has constant voltage and when you press the horn button you complete the ground.
I guess my guestion is did they use a horn relay in 1949?

bill1949,

I think this might be a gray area. The '48 wiring diagram shows no relay, but of course this isn't your '49. My first thought would be if your rig HAS the relay, and it appears stock, then it came with it.

I sort of thought this might have been a transitional year for the relay...some had them, some didn't.

I have enclosed a link to a thread on this subject earlier in this forum.

Sorry I can't give you a definite answer, I'll bet someone will though.


http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=3;t=000636#000006

Stuart

My '51 GMC did not have a relay, but my '53 does. I think someone added the relay to yours in later years when your horn may have had to have repairs. Cecil.........

Just shootin from the hip here, but I have seen horns that are grounded thru the body, those require a relay, and then there are those that have a pos & neg terminal, which can be run thru the horn button as the ground side -or- can be grounded & run thru a relay.
I've noted that some low power horns are fine to run thru the horn button, but the high amperage blaster horns need a relay so you dont burn out the brush contact on the steering wheel.
I'm gonna use a relay either way as I plan on putting in a nice air horn.

I don't know if this will help, but my 49 3100 has a horn relay mounted to the firewall. Atomarc is right about the 49 being a "crossover" year. Early 49's used up the last of the 48 parts. For instance, my truck has the later style 4 point cab mounting fastening system, but has the earlier stlye headliner "screw" in bow (?).
Which wiring harness did you get?

My '50 3100 does not have a horn relay and I do not believe it ever had one. But it was not working prior to current restoration so this may not be definitive.

I had the same wiring question with my 49 GMC. No relay on the wiring diagram, no wires in the harness for a relay, nothing on the firewall.
On the other hand the diagram and wires were for a 6-volt system, which mightn't have done any harm wired directly to the horn. But, since the horn wire in the steering column is always on, it seemed like a 12-volt system would burn it out. A relay, using lower voltage, seems like the way to preserve it.

http://chevy.tocmp.com/1948_51truckshop/51ctsm1202.htm
Maybe better eyes than mine can tell if it had a relay.

49_chevy_truck,


I sure don't see a horn relay on this diagram.


Stuart

Hey Guys

I know that the 49's are a cross over year. I have the 5 point cab mounts, but I have the door weather stipping that is bolted on.
As for the horn relay I looked at 3 wireing diagrams and none had a horn relay. I purchased the harness from M&H Electrical.

I changed to 12 volts. Now if I understand correctly 12 volt has more voltage by less ampage and hoping to be able to use the wireing in the steering column.

bill1949,

The horn will work fine wiring it the way you want...through the steering column sans relay.

Be sure to fuse the line, or supply side of the horn. The relay made the horn more energetic, and the fact that the horn button on the steering wheel was only switching the small relay coil made it a little safer...but it's fine the way you intend on doing it. It was done in millions of cars for many years that way.

You are correct, if you double the voltage, you half the amperage a device will draw. Your horn is going to be on steroids on 12 volts...be prepared.

Stuart