3 replies to this topic

[austin84]

Hey guys...

Jap spec 1993 rover mini spi.

So the horn on my mini does not work. It used to... But no longer.... Here's what happens: with the car off but key in the II position, I push on the horn button and the dash gauge lights dim and the fuel pump slows down. If I hold it... The fuse blows and my radio stops working.
With proper fuse, everything works including hazards, directional indicators, brake failure, dip beams etc. I have removed the two horns, cleaned all the prongs and spade connectors. I have sprayed contact cleaner on all the plugs beneath the dash.

People say its a ground or short issue... But I don't know how to check for that. I followed the purple line to the 4 fuse fuse block... Cleaned that up and made sure the fuse was ok.

Where do I go from here?

[Craig89]

There is likely to be a fault with the cable or the horn. The easiest way to check the horn is to swap it for a known working one. If the fuse continues to blow then I suspect there is damage to the cables insulation (live feed to the horn) and this is shorting on to the body. The best way to check this is to follow the cable back from the horn to its source checking for damage. HTH

[eero]

Sounds like a short and it could be the horn itself shorting out. Does it make any sound at all? Grounding issue would mean it just doesn't work - blown fuse indicates a direct connection to ground in the circuit.

 

Replacing the horn right away could not solve the issue  - the problem might somewhere else and you'd be running around in circles.

 

Get a circuit tester, any that measure DC voltage and resistance will do. I'd first start by measuring the voltage between the horn terminals without the button pressed - this should be 0. Now with someone pressing the button see what the voltage does, should be close to the battery voltage (measure that first from a good known location). And then check the resistance of the horn itself - I'm not sure what it should be, maybe even no connection, but shouldn't be 0.

 

Then disconnect the horn terminals and measure resistance of the cable with ground (body) - one should be 0 or close (black wire), the other should show no connection (purple/black). Would start tracing the cables when something off.

 

 

Other ways to test would be to put the horn directly to a 12V source and see if makes a sound. Be careful though, the circuit should be independent and could damage anything if there is a fault in the horn (thats what fuses are for). If it now works, but not in the car, it's probably the circuit.

 

To test the circuit put a 12V lightbulb in place of the horn and see if you still get the fuse to blow and if the light works in the circuit.

 

 

But i'd suspect the connection from the switch to the live terminal of the horn (purle/black wire) is shorting somewhere.

[KernowCooper]

Pull the wires off the horn and then retest as per you problems above, if it continues to blow a fuse the horn wire is shorting to earth, if it does not blow the fuse the fault is internally in the horn/s