REEVSY

Member
Hi, I have a 1993 Defender pickup (cab). With TDI 300. One evening During the very cold period my horn started to sound while parked up at home. So far I’ve changed the horn unit for new, I’ve changed the full indicator stork on the wheel (after checking I found the old one to be working perfectly). Somebody had at one time added a bonnet open contact on the fire wall and between the hood so I renewed this, the horn still continues to sound continually! I even un plugged the bonnet open contact but the horn still sounds. I’ve checked the horn wiring back to the loom and it all ok. I checked the loom at the steering wheel and it looks good. I’m now out of ideas and any Ideas or input would be great fully received.
 
Might be a bit of an obvious question - but is it the car horn..or the alarm horn that goes off?
o_O
It’s the car horn….. as far is I know and I’ve had the vehicle 10 year there is no alarm fitted. Other than the bonnet switch.
 
Hi, I have a 1993 Defender pickup (cab). With TDI 300. One evening During the very cold period my horn started to sound while parked up at home. So far I’ve changed the horn unit for new, I’ve changed the full indicator stork on the wheel (after checking I found the old one to be working perfectly). Somebody had at one time added a bonnet open contact on the fire wall and between the hood so I renewed this, the horn still continues to sound continually! I even un plugged the bonnet open contact but the horn still sounds. I’ve checked the horn wiring back to the loom and it all ok. I checked the loom at the steering wheel and it looks good. I’m now out of ideas and any Ideas or input would be great fully received.
If the live feed to the horn is still live with the ignition switched off, the horn must be picking up a live from somewhere else. Possibly by shorting from another live wire inside the loom.

I don't know what the "bonnet open contact" is, but I would remove it altogether. Take it out of the equation.
 
Thanks for this. I did remove the bonnet switch. As far as I under stand the horn has a live feed ignition on or off …. If somebody could confirm this? By the way I do have a live feed ignition on or off.

If the live feed to the horn is still live with the ignition switched off, the horn must be picking up a live from somewhere else. Possibly by shorting from another live wire inside the loom.

I don't know what the "bonnet open contact" is, but I would remove it altogether. Take it out of the equation.
 
Thanks for this. I did remove the bonnet switch. As far as I under stand the horn has a live feed ignition on or off …. If somebody could confirm this?
As far as I know, everything except the wire to the starter should be off with the ignition off. Except any alarm that is present, but you haven't got one.

When previous owners have messed around with the electrics, anything becomes a possibility. The dreaded Scotchlocks, wires twisted together and wrapped with tape, lives taken from already full fuse holders, or direct from the battery, etc. etc.

Try testing the wires that used to go to the bonnet switch, see if either of them is live all the time.
 
As far as I know, everything except the wire to the starter should be off with the ignition off. Except any alarm that is present, but you haven't got one.

When previous owners have messed around with the electrics, anything becomes a possibility. The dreaded Scotchlocks, wires twisted together and wrapped with tape, lives taken from already full fuse holders, or direct from the battery, etc. etc.

Try testing the wires that used to go to the bonnet switch, see if either of them is live all the time.
Thanks I’ll do that tomorrow.
 
Thanks I’ll do that tomorrow.
I add this info to add to the vehicle history when with me.
When I got the vehicle some 12 years ago the lights kept giving issues, I renewed all the bullet connectors with new and light perfect from then on. At this time I obtained some LED bulbs for the side lights and number plate light , these early LED where polarity sensitive and I got the wrong polarity so I swapped the power + - at the back of the lights around and the lights works and have done so for the last 10 years so can’t see why this should now cause a problem. The rest of the wiring Looks OK.
 
Thanks I’ll do that tomorrow.
Update!

Ok I’ve tested the bonnet switch with no voltage so I’ve left unplugged. As far as I can see on the wiring diagram 12v from battery via the fuse box to the horn button which is simply a make or Brake. I’ve removed the covers from around the horn stork and from what I can see the wiring and connections look good. So I’m back to square one. I’ve still got a live 12v feed to the horn with ignition switch in the off position and keys removed. I’m now stumped so I think I’ll have to bite the bullet and take it to an auto electrocution.
 
Update!

Ok I’ve tested the bonnet switch with no voltage so I’ve left unplugged. As far as I can see on the wiring diagram 12v from battery via the fuse box to the horn button which is simply a make or Brake. I’ve removed the covers from around the horn stork and from what I can see the wiring and connections look good. So I’m back to square one. I’ve still got a live 12v feed to the horn with ignition switch in the off position and keys removed. I’m now stumped so I think I’ll have to bite the bullet and take it to an auto electrocution.
You could do that. Or you could identify the live for the horn on the back of the ignition switch, and run a new wire from that to the horn push, and then to the horn. And just leave the old wire disconnected at both ends.
 
Iirc the horn circuit is/was the odd one out and is live all the time, and the switch/relay whatever earths the circuit out, Iirc this is to save damage to the switch/relay contacts?
 
Two things need to be established that I can see(and I'm no spark!).
1- does the horn work via a live feed or and earth feed? My 86 is a live feed.
2- does this model have a horn relay? If so, it quite possibly has welded contacts.
 
Two things need to be established that I can see(and I'm no spark!).
1- does the horn work via a live feed or and earth feed? My 86 is a live feed.
2- does this model have a horn relay? If so, it quite possibly has welded contacts.
Ok thanks…

yes the horn has a live feed. As for a horn relay I don’t know! I understand not however, there is a number of relays in the engine bay. Il try and get some photos tomorrow. According to the wiring diagram the power goes from the + side of the battery through the fuse board to the horn stork! From the horn stork via the loom to the horn positive one side of the horn and earth return back. Both the wire are via the loom. I’ve pulled the wires from the horn out via the head light access and they both look in good condition. My understanding I should not have a live feed at the horn till the pushhorn on the stork is closed … the horn stork is new and the old one tale off is working ok on test on the bench.
 
There should be relays behind the fuse box cover in front of the gear lever. Mine(1986) has a few behind the metal plate that you'll see when you take the plastic fuse box cover off. This cover usually has the diff lock guide on it.
 
There should be relays behind the fuse box cover in front of the gear lever. Mine(1986) has a few behind the metal plate that you'll see when you take the plastic fuse box cover off. This cover usually has the diff lock guide on it.
Ok,thanks I’ll have a look. It could be a bad relay if only I can ID it.☺️
 
Hi, I have a 1993 Defender pickup (cab). With TDI 300. One evening During the very cold period my horn started to sound while parked up at home. So far I’ve changed the horn unit for new, I’ve changed the full indicator stork on the wheel (after checking I found the old one to be working perfectly). Somebody had at one time added a bonnet open contact on the fire wall and between the hood so I renewed this, the horn still continues to sound continually! I even un plugged the bonnet open contact but the horn still sounds. I’ve checked the horn wiring back to the loom and it all ok. I checked the loom at the steering wheel and it looks good. I’m now out of ideas and any Ideas or input would be great fully received.
 

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