Discovery 1996 - Horn problem

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
D

dgcamel

New Member
Posts
7
Location
Malta
Left the discovery parked for a week, and my horn did not work upon my return.

Car is a 1996 discovery with non-airbag steering wheel (300tdi engine). Checked all fuses, and can confirm that there is 12v upto the horn button on the steering wheel, but not at the actual horns themselves (behind front grille).

Where does the wiring go from the steering switch? Is there anything common to look out for? Any guidance as to the actual wiring would be mostly appreciated.

Thanks,

dgcamel
 
shocker said:
You have obviously tried touching the two contacts at the wheel to eliminate the possibility of bad switch
Click to expand...

Thanks for your reply. Yes I have - checked with multimeter and can confirm that when the two ends are touched both sides measure 12v.

The problem is I could not see where the wiring goes from the steering wheel. Does it go to the fuse box, or maybe to the relay? Or directly to the horn?
 
From my Haynes manual seems:
fuse 4 in engine fuse box
purple/brown to
relay 21
purple /green from relay 21 to horns
purple/orange from horn push to relay 21
relay "21" is located behind passenger footwell side panel.
Hope this helps & good luck. Maybe check horns are ok by sparking 12v across them too?
 
dgcamel said:
Thanks for your reply. Yes I have - checked with multimeter and can confirm that when the two ends are touched both sides measure 12v.

The problem is I could not see where the wiring goes from the steering wheel. Does it go to the fuse box, or maybe to the relay? Or directly to the horn?
Click to expand...

No did you touch the two contacts together? 12v on a meter and 12v with enough current are two completly different kettle of fish.
 
dgcamel said:
Thanks for your reply. Yes I have - checked with multimeter and can confirm that when the two ends are touched both sides measure 12v.

The problem is I could not see where the wiring goes from the steering wheel. Does it go to the fuse box, or maybe to the relay? Or directly to the horn?
Click to expand...

Strange you finding volts, all the horn push does is provide an earth return for the horn relay.

The horn relay could be suspect, so as it's a common standard 4 pole just swap with another fron same area of relays and try the horn.

To bypass the horn push and rotary coupler go direct to the horn relay terminal 86 remove the purple/orange wire and earth it the relay should operate and horns sound.

Relay terminal 87 is the supply to the horns therefore if you remove purple /green wire and provide 12volts to it and the horns they should sound, but beware the horns take a high current.
 
discool said:
Strange you finding volts, all the horn push does is provide an earth return for the horn relay.

The horn relay could be suspect, so as it's a common standard 4 pole just swap with another fron same area of relays and try the horn.

To bypass the horn push and rotary coupler go direct to the horn relay terminal 86 remove the purple/orange wire and earth it the relay should operate and horns sound.

Relay terminal 87 is the supply to the horns therefore if you remove purple /green wire and provide 12volts to it and the horns they should sound, but beware the horns take a high current.
Click to expand...

Yes it will provide a return path to earth but what do you think it is returning? If the circuit is as you say then there will be 12v to the relay, through the coil then to the switch which when pushed allows current to flow through the coil to deck. When he meters it out he is getting the 12v through the coil on one side, and ground on the other, so the meter will show this potential difference.
 
Thank you all!

I have tried touching the horn contacts together in the steering wheel but horn does not sound. I even joined the two wirings ends together (thus bypassing the horn switch) but still it will not sound. The actual horns are ok.

discool - I also found it strange for the horn switch to be switching a 12v supply rather than earth - never had this before on another car.

Will try and replace the relay first and then also 'shorting' it as suggested. However, it's 31degrees (celsius) outside right now so will have to wait for this evening :)

thanks
 
dgcamel said:
discool - I also found it strange for the horn switch to be switching a 12v supply rather than earth - never had this before on another car.
Click to expand...


You are both missing the point here, it is switching the earth, but how do you think it switches?

That 12v you are getting has gone via the relay, next stop earth which lets the current flow and the coil can then operate to close the relay.

Take the relay out, put your meter onto DC volts, with the neg probe to a good earth point prod the sockets with the positive probe until you find 12V. Now take this feed and using a piece of wire or even a paperclip or something or your meter on amps mode jump from the 12v feed to the horn feed, does it sound?

Now check that the relay is getting 12v to the coil when the horn switch is pressed by getting someone to press the horn while you meter out the coil feed, either to a good earth or to the horn feed, if this is going live when the horn is pressed, it's the relay, or alternatively, just whip a relay out elsewhere to try it.
 
Last edited:
You are both missing the point here, it is switching the earth, but how do you think it switches?

Err... what switches? one side of switch is to the device and in this case a relay, the other side is to ground (earth) press the switch the circuit is made, that's how I think it switches.

Or perhaps do you mean something else?.
 
No, I don’t mean anything else, you have misinterpreted me. I'll explain.

They were confused about seeing 12v to one side of the switch. Now, in order for a switch to work there must be a potential difference between the switching terminals, if not it will make not a blind bit of difference if the switch is open or closed.

So my point was, 'How do you think it switches', there needs to be something, in this case 12v at one side, which has already passed through the relay in order for it to close the circuit and complete the return path.

It was theoretical, following now? Your self-conceited comments don’t help anyone.
 
Last edited:
ok brake it down with someone in the car,

first multimeter will be around 12v

check stering wheel switch works use ether a multimeter or test lamp if ok move on to the next thing.

re

check horn itself clean wirering check conecters again are geting a feed do this with a
multimeter or test lamp when horn is switch is pushed. if geting feed then horn is fooked if no feed then move to the next point

check fuse is suplying feed again multimetier or test lamp after that realy if fitted.

last is the realy and discomainea has explaned how very well to do this

after that it is a wireing problam
 
You must log in or register to reply here.

Similar threads

mjr92
Horn and flash problem
Replies
12
Views
660
mjr92
mjr92
H
Discovery Sport Sept 2015 - Breakdown
Replies
14
Views
2K
Phil-G
P
J
Help please! Electrical issue with 1995 Defender 110 County, 300 tdi
2
Replies
35
Views
2K
Oliverryan96
O
H
Air horn wiring advice...
2
Replies
25
Views
4K
Hector the Bad
H
K
What money should I be asking?
2
Replies
27
Views
4K
Karls
K
Back
Top