1962 C10 Horn Installation

[WRO44]

OK Gents I have a 1962 C10 that currently has no horn. I got a horn from a local yard today but now I am trying to figure out the installation. I know I need to get a horn relay. The relay gets a hot wire from the battery, a wire to the horn, and a black wire from the horn button.

The problem is that I trace the black wire from the horn button into the wire bundles and have no clue where it goes to. Where is it supposed to come from originally??? Any advice or suggestion are welcomed!!

[cb1965]

on mine, it comes from wiring harness on steering column out to firewall. green wire.mine is a 65 tho. not sure if all years were wired the same.

[protrash64]

The black wire starts at the relay and continues up to the large connector on the firewall. It should continue thru the harness until it meets the turnsignal bundle going into the column.

Power will run from the horn relay up into the column and when the button is pressed it grounds the black wire to the internal metal of the steering shaft.

I'm most familar with 64-66, but it should be similar.

[goatless]

That image has been very helpful for me in my wiring efforts, but either I'm not seeing it or it's missing the ballast resistor wired between the positive coil and the firewall (the 20 W/OR/PPL purple wire).

Might lead one to believe that in a points setup the coil always gets 12 volts as opposed to only when cranking the engine. I am assuming it's a points setup because of the yellow 20Y wire going from "R" on the solenoid to the positive side of the coil.

IIUC, the points can't handle 12 volts full-time, so the resistor reduces input to the coil to ~9 volts when the ignition is on, but when cranking, the "R" supplies 12 volts to help start the engine.

[ray_mcavoy]

Originally Posted by cb1965

.... not sure if all years were wired the same.

Yes, the 60 through 66 horn wiring is similar for all years. Although some of the early years had the color coding of the black & green wires switched around opposite of the later years. And many of the later years also had a power distribution buss bar built into the horn relay assembly.

Originally Posted by goatless

That image has been very helpful for me in my wiring efforts, but either I'm not seeing it or it's missing the ballast resistor wired between the positive coil and the firewall (the 20 W/OR/PPL purple wire).

Might lead one to believe that in a points setup the coil always gets 12 volts as opposed to only when cranking the engine. I am assuming it's a points setup because of the yellow 20Y wire going from "R" on the solenoid to the positive side of the coil.

IIUC, the points can't handle 12 volts full-time, so the resistor reduces input to the coil to ~9 volts when the ignition is on, but when cranking, the "R" supplies 12 volts to help start the engine.

The 20 W/OR/PPL (white/orange/purple, but pictured solid purple on that diagram) wire is a special resistance wire that takes the place of a ballast resistor. The use of a resistance wire (in place of a ballast resistor) was fairly common practice on many 60's & 70's GM vehicles.

[goatless]

Originally Posted by ray_mcavoy

Yes, the 60 through 66 horn wiring is similar for all years. Although some of the early years had the color coding of the black & green wires switched around opposite of the later years. And many of the later years also had a power distribution buss bar built into the horn relay assembly.

The 20 W/OR/PPL (white/orange/purple, but pictured solid purple on that diagram) wire is a special resistance wire that takes the place of a ballast resistor. The use of a resistance wire (in place of a ballast resistor) was fairly common practice on many 60's & 70's GM vehicles.

Thanks for the clarification. My '64 has a ballast resistor. Apparently, it wasn't properly wired, as there's only one wire going to the + on the coil, and it comes from the ballast resistor. Guess that means it wasn't getting the full 12volt boost when starting.

[Brim]

Going through this now on my 64 C10. There is no horn and I'm not sure where to begin if I purchase an aftermarket horn from an auto parts. I know I can mount it somehwere near the horn relay and voltage regulator like maybe on the frame. But I'm not sure how to tie it in to the wires (Dk Green & Black) coming from the bulkhead?
How did you reslove it?

Thanks,
Mark

[The Rocknrod]

http://67-72chevytrucks.com/vboard/s...32&postcount=2
and
http://67-72chevytrucks.com/vboard/s...&postcount=201

[ray_mcavoy]

Originally Posted by Brim

Going through this now on my 64 C10. There is no horn and I'm not sure where to begin if I purchase an aftermarket horn from an auto parts. I know I can mount it somehwere near the horn relay and voltage regulator like maybe on the frame. But I'm not sure how to tie it in to the wires (Dk Green & Black) coming from the bulkhead?
How did you reslove it?

Thanks,
Mark

Hi Mark,

Does your truck still have the factory horn relay installed?

If so, those dark green and black wires from the harness should have a 2-terminal plug that plugs into the relay. The dark green wire is the output from the relay that would have gone to the original horn. So all you should have to do is locate the other end of that dark green wire and connect it to the replacement horn.

The factory horns were grounded via their mounting bracket to the radiator support. But many newer / replacement horns will have 2 terminals (power and ground). If you get one of these, simply hook the dark green wire to the horn's power terminal and add a ground wire to the other terminal.

[Brim]

Originally Posted by ray_mcavoy

Hi Mark,

Does your truck still have the factory horn relay installed?

If so, those dark green and black wires from the harness should have a 2-terminal plug that plugs into the relay. The dark green wire is the output from the relay that would have gone to the original horn. So all you should have to do is locate the other end of that dark green wire and connect it to the replacement horn.

The factory horns were grounded via their mounting bracket to the radiator support. But many newer / replacement horns will have 2 terminals (power and ground). If you get one of these, simply hook the dark green wire to the horn's power terminal and add a ground wire to the other terminal.

Thanks a bunch for clarifying that for me. I added it today, it's the aftermarket 2 prong from LMC. I also picked up the bracket. Got it installed today but I figured it needed a ground and I didn't have time to add one. I will add one tomorrow and hopefully it will work.

Bracket had to be notched just a tad to clear the horn relay but it didn't take to long. Added it in the stock location.
A couple of pics. I guess I can just ground the wire to the radiator core support?

[Brim]

Added the ground wire and the horn works. Appreciate the info and help. Now need to get my tail lights worked out. Both are blinking at the same time regardless of which direction I choose. Front signals function properly.