Hello all,
We are Military Mobility, a 501(c)(3) non-profit that provides off-road expeditions and training to veterans in need. Thanks in advance for the help!

We were donated a 2004 Disco 2 HSE and it's in great shape. Been fixing little things and the last bit is the horn. I've scoured the forums and got a lot of info but at a point I need to ask for help. I'll be as concise yet detailed as possible, with pics as well. The previous owner did some wiring to fix the cruise control (it currently works fine) from the rotary coupler so I have a feeling that's where things went wrong. Here we go:

WHAT"S BEEN DONE ALREADY

-Supplied 12v to both horns, they both work.

-Swapped out Horn Relay (R13) with others, no change

-ALL fuses in the entire vehicle are good,

-Swapped out the fusable link 8 (50amp), which connects with Fuse 16 (10amp for Horn), no change

I found this advice on the forum (paraphrased) and have conducted the testing:

-Check the ground path from the horns to the relay

-Pull relay number 13 out. the socket will have 4 or 5 connections in it (3 vertical, 2 horizontal)

-At least 1 (maybe 2) of the 3 vertical slots will always have +12 volts on it and 1 will have -12 volts while the horn button is pressed.

-Connect the positive lead of the meter to the positive terminal of the battery and the negative lead of the meter to the vertical slots on the socket one by one. Have someone press the horn switch on and off for a few seconds as you probe each slot with the meter leads, you should find one slot that will flash +12 volts on the meter every time the horn button is pressed, if you don’t your problem is in the ground path. If you do your problem is in the positive path.

-I did this and found a constant 12V from the top (towards centerline of vehicle) horizontal slot of the relay

-I got no other power reading, constant or flashing from any other slot


WIRING OBSERVATIONS:

3 wires cut from rotary coupling connector (Yellow/ w Black stripe, Green/ w Orange stripe, Brown (mauve)/ w Black stripe, and 3 new wires ran directly to Cruise Control Actuator. There are also 3 wires cut at the Cruise Control Actuator. They are:

Black/ w yellow stripe

Black/ w Dark Red stripe (could be a brown)

White/ light blue stripe

*So aside from the changing color of the wires, it makes sense the previous owner may have bypassed a CC wiring problem and ran new wires


POWER WIRING FINDINGS (with ignition off)

From Coupler at Steering Wheel:

Grey/ Black to battery gets me a solitary beep, that’s it

From underside fuse of R13 (Horn)

Grey/ Black gets nothing

Orange/ White get solitary beep

Brown/ Purple gets solid tone

OK THAT'S WHAT I GOT. Please keep in mind I am not the best at wiring or reading diagrams so speak to me like a caveman! Thanks again!!


3 wires cut from rotary coupling connector (Yellow/ w Black stripe, Green/ w Orange stripe, Brown (mauve)/ w Black stripe, and 3 new wires ran directly to CC Actuator


View of the wiring harness that was cut


Note: 3 wires cut at the CC Actuator. They are: Black/ w yellow stripe Black/ w Dark Red stripe (could be a brown) White/ light blue stripe These wires were replaced by the red, white, blue

 

I read most of what you wrote and apparently someone butchered the wiring. I would recommend getting a replacement slip ring, wiring harness in steering wheel, and wiring harness from slip ring to the fusebox.

 

Thanks for the reply, I will keep that in mind for sure. I'm going to do just a bit more troubleshooting first, think I just need to find which wires ground the horn buttons and the relay. Key word there is "think"