4 replies to this topic

[minivictor]

Hoping someone could shed some light on a ground issue. I installed a single aftermarket horn and wired it up just as the diagram below. The problem is that when I press the left-hand stalk to active the horn, the relay coil does not activate. I am certain the circuit works because I connected Relay #86 pin to bare metal on the chassis and the horn sounded off as expected.

 

 

Is the horn switch known to go bad (on the steering column)? Or perhaps is there a way to clean the terminal points?

 

What's even more odd is that I connected one end of a multimeter to a good ground and the other end to the Purple/Black wire, checked for continuity and the meter sounded off as expected. At this point, I can use an aftermarket switch, but I was hoping to use the button built into the car.

 

[paulrockliffe]

That wiring diagram is positive ground isn't it? Your mini should be the other way around, with the power going into the switch then to horn then to earth rather than power going through the horn and being earthed through the switch.

[paulrockliffe]

Oh, I should add if you've wired it like that the horn switch is shorting the battery when you press it, which will set the wiring on fire if you hold it long enough.

[Spider]

Depending on what year model your Mini is, some Horn Switches switch to Earth (as your diagram) and some switch +ve.

 

Are you sure (and checked with a meter) that the switch is switching to Earth?

[minivictor]

^^ I have a 1972 Mini Mk3. I am wiring an aftermarket horn, not the original horn. 

 

Thanks to both of you, I resolved the issue by confirming that the Purple/Black wire does indeed carry 12volts when the Horn button is pressed. Once I wired the relay accordingly, my horn is now functioning as expected!

 

I assumed the Purple/Black wire was Ground because nearly every reference of the horn switch was pointing to a negative ground. Additionally, my experience with more modern vehicles has always involved negative horn triggers. ALSO, when I performed a continuity test on the Purple/Black wire, my meter would beep each time I pressed the horn switch (and with one side of the meter to ground, with the other on the Purple/Black)

 

Overall, lesson learned: Test each wire accordingly even if you have the schematic

 

Thank you both!

Edited by minivictor, 27 January 2018 - 03:59 AM.