1993 Defender horn

REEVSY · Feb 19, 2023

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.

Beneagles · Feb 19, 2023

Might be a bit of an obvious question - but is it the car horn..or the alarm horn that goes off?

REEVSY · Feb 19, 2023

Beneagles said:
Might be a bit of an obvious question - but is it the car horn..or the alarm horn that goes off?

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.

Turboman · Feb 19, 2023

REEVSY said:
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.

REEVSY · Feb 19, 2023

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.

Turboman said:
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.

Turboman · Feb 19, 2023

REEVSY said:
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.

REEVSY · Feb 19, 2023

Turboman said:
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.

Turboman · Feb 19, 2023

REEVSY said:
Thanks I’ll do that tomorrow.

Let us know how you got on.

REEVSY · Feb 19, 2023

REEVSY said:
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.

REEVSY · Feb 20, 2023

REEVSY said:
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.

Turboman · Feb 20, 2023

REEVSY said:
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.

lynall · Feb 20, 2023

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?

REEVSY · Feb 20, 2023

https://app.photobucket.com/u/northwestlinux/p/45e24268-ee01-40df-8808-af35be004f21

wiring diagram

REEVSY · Feb 20, 2023

Turboman said:
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.

Yes I’m thinking of this but my age makes some jobs difficult, 80 now.

Flossie · Feb 20, 2023

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.

REEVSY · Feb 20, 2023

Flossie said:
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.

Flossie · Feb 20, 2023

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.

REEVSY · Feb 20, 2023

Flossie said:
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.

Flossie · Feb 20, 2023

On mine there is a sticker on the rear of that cover telling you what's what.

REEVSY · Feb 21, 2023

REEVSY said:
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.

1993 Defender horn

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