Horn Feed

[willincalgary]

My horn quit working during a recent engine rebuild. I was attempting to resurrect it today and was stumped. I can see the brown wire feeding power to the button from the ignition. I can see the brown and black leaving the button, heading through the firewall and into the main portion of the wire harness and that is where I lose it. I can not for the life of me find where the brown and black comes out of the harness.
The car is wired as per the negative earth with headlights in the wings in the green bible.
Any help on where it emerges?

[Skookumchuck]

not on topic but do you ever get over to the Cranbrook area with your Rover? If you do stop by there is a couple of defenders in Cranbrook maybe we can run some of the trails around here. I have a 1968 109, Mark in Cranbrook has a D-90 and we are always looking to find some other Rover owners to go play with.

[TeriAnn]

I don't know about the newer trucks but the older ones are wired:

unswitched 12V to horn (brown wire) -> other horn terminal to horn button (brown/black wire) -> Horn button to ground (short black wire).

I've found the horn seems to be louder if you add a relay to that circuit.

[mearstrae]

I hope this helps out... It's how it's wired on my '76.

Brown wire: [full power, unswitched] from Ign. switch to horn button.
Black/Brown: from horn button to end of the engine bay harness (this is where it comes out). & connected to horn.
Black wire: from horn to Earth.

Now, all you have to do is find the wire in the harness and hook it to the horn. Hmmm, back where you started.

'95 R.R. Classic LWB
'76 Series III Hybrid 109
'70 Rover 3500S

[TeriAnn]

I hope this helps out... It's how it's wired on my '76.

Brown wire: [full power, unswitched] from Ign. switch to horn button.

'95 R.R. Classic LWB
'76 Series III Hybrid 109
'70 Rover 3500S

Can you do that with a SIII?????? On SII & IIA when you push the horn button it makes a ground connection. The centre button is floating when & pressed it contacts the vehicle ground. That's why the unswitched 12V goes to one end of the horn and the the other end of the horn goes to the floating connection of the horn button.

[SafeAirOne]

Can you do that with a SIII?????? On SII & IIA when you push the horn button it makes a ground connection.

Yup--With the SIII horn button on the end of the turn signal stalk, power is already right there, so hitting the horn button just sends 12v out to the horn. The other terminal on the horn itself goes directly to ground.


If the horn was located in the inside of the radiator suppport panel on the SII/IIA, I'd confine my wire search to that part of the harness that lies within 18 inches of there.

If I had pre-SIII Rover, I'd just go out to my driveway and have a peek for you, but alas, I have a SIII...

[mearstrae]

Hmmm... Older Series ?: Power to horn then back to horn button and then to earth. Seems like the same idea only reversed. I was curious so I checked my '70 Rover (car) and it's wired like the '76 series, including the wiring codes. But they're pretty modern compaired to a '59 series.

'95 R.R. Classic LWB
'76 Series III Hybrid 109
'70 Rover 3500S

[willincalgary]

I hope this helps out... It's how it's wired on my '76.

Brown wire: [full power, unswitched] from Ign. switch to horn button.
Black/Brown: from horn button to end of the engine bay harness (this is where it comes out). & connected to horn.
Black wire: from horn to Earth.

Now, all you have to do is find the wire in the harness and hook it to the horn. Hmmm, back where you started.

'95 R.R. Classic LWB
'76 Series III Hybrid 109
'70 Rover 3500S

This is exactly how mine is set up. Technically I have a SII but the wiring is much more modern. I can't find the Brown/Black exiting the wire harness. The harness that travels down the right side of the engine bay has the connections to the alternator within it but nothing else (which is interesting as the cold start switch in the head is right beside the alternator and yet this wire is not grouped with the others).

I think I need to see whether the folks who did some recent work perhaps connected it somewhere else thinking it was for some other purpose. I seem to remember having a lot of wires connected to my starter switch. Some of these are brown, but of course, some of them should be.

GRRRRR.