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Horn Relay or O/D Relay

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brent615

Jedi Trainee
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Help....I am so confused.

The problem: Horn doesn't work

Went to chek wiring. Started with online wiring diagram and Bentley book. Found that acording to both the horn relay has 4 wires, (purple, purple, purple/blk, and purp/yel). I locate the horn relay in the inner fender just a few inches toward the windscreen from the fuse box. Relay is marked LUCAS with leads marked C1, C2, W1, and W2. I am pretty sure my relay is bad.

Here is where it gets interesting.... TRF has a horn relay for about $59. I went online looking for a deal and found a "Overdrive relay" on Ebay that looks EXACTLY like my "horn relay" for $10.00. Checked out Rimmer Bros. and find another Overdrive relay that looks just like my "horn" relay.
112a.gif
Item 67 and 72 are the horn and overdrive relays respectively....THEY LOOK THE SAME TO ME! And they both look like what I need to replace.

The question: Is the horn relay indeed the small silverish relay marked LUCAS C1 etc. etc. with all of the purple wiring coming in and out?

Question 2: Did they (TR6) all come wired for OD whether they had OD or not? If not, what is the block below the horn relay without the 9 leads and many wires?

Sorry to be long winded but man am I confused. Not to mention cheap and i don't want to spend $59 when I only need $10.
 
Why do you think the relay is bad. Just went through this with a gentleman in Canada and 9 times out of 10 it's the ground.
 
They are the same on my 74. And purple wires indicate the horn circuit.
Moss has the same part# for both the horn and OD relay.
Do you hear the relay "click" when you push the horn button ?
Mine built up corrosion on the points. I removed the silver metal weather cover, cleaned up the contact points and reassembled with a bead of silicone around the base of the weather cover because the gasket was not in the best shape.
 
The PO had bypassed the relay altogether and wired the horn to the battery and a button that he placed between the gear shift and the hand brake. I replaced the wires to their proper location as indicated on the wiring diagram and don't get any clicking in the relay when I ground the horn button wire.
 
Might just be the contact points or corrosion on the circuit contacts in the relay. If you want to use a universal electronic relay vs the original electromagnetic relay, you can. They are inexpensive and available at the parts stores. Relays as you probably know are switches that eliminate high amperage (heat) at the more delicate dash switches.
The headlights didn't utilize a relay, one reason the "clear hooter" switches are hardly seen on older cars.
BTW, some cars, ones with OD, may not have used a relay for the horns.
 
brent615 said:
I haven't located teh ground for the horn. Actually, I assumed the horn system was grounded at the horn mounting bracket. Where should the ground wire be?
Click to expand...
Look for a black wire with a female spade connection.
 
brent615 said:
I haven't located teh ground for the horn. Actually, I assumed the horn system was grounded at the horn mounting bracket. Where should the ground wire be?
Click to expand...

2places

1.On the coupler there is a wire that ties the top to the bottom shaft

Hornground.jpg


2. At the rack there should be a wire from the shaft to the rack bolt where you fill it.

Hornground2.jpg
 
As Don points out, those are the ground connections for the horn button, which activates the relay. Once the relay is activated, the actual horns are grounded by a black wire that plugs onto the horn itself.
 
<span style="color: #3333FF">As Don points out, those are the ground connections for the horn button, which activates the relay. Once the relay is activated, the actual horns are grounded by a black wire that plugs onto the horn itself.</span>


WOW....I actually have those!!
 
Well that's good. A lot of times when you see where a PO has wired up a circuit, such as you found for the horns, it's because something stopped working and he either couldn't find the culprit or found it and decided not to make a repair. Jury rigged horns are pretty common along with ignition switches.
 
Easy way to tell if it is a ground. Touch a wire to the brass ring under the wheel and the other side to ground. If it works there is your culprit. If not go to plan b.

Plan B- Do you have power to the horn button?
 
Don,

I ran my horn grounds into new grounding blocks.
I think you did the same?

d
 
Actually no,
Well sort of. the end at the rack goes to the front grounding block on the valence.

DSCF3716.jpg
 
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