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I checked the electrical diagram. It shows there should be a horn relay and probably some fuses. Supposed to be on the left-hand side, by the left fender:
However, I was not able to find any relays there. I see fuses, but not relays:
Foggy memory disclosure here, but I think you'll find it forward of the coolant tank. Almost directly behind the LH headlamp. You'll have to look downwards...it's at about the same level as the coolant tank.
If that doesn't pan out someone else will come along
Foggy memory disclosure here, but I think you'll find it forward of the coolant tank. Almost directly behind the LH headlamp. You'll have to look downwards...it's at about the same level as the coolant tank.
DD
Thanks, Doug. Found them.
They were hiding behind black plastic cover, right next to the LH head lamp.
So, I removed the cover and I see three relays, arranged vertically:
- Big boxy silver one
- Round bright-red one
- Round black one (at the bottom of the row)
Anybody knows which one is the relay for the horn and how to troubleshoot if it is working as intended?
If it happens when you turn the steering wheel, then the spring assembly down in the column is shorting to the column and activating the horn.
Here is how I fixed mine. Read through the whole post as I ended up fixing it twice, the second time was 5 years ago and it's been fine ever since. The only down side to the copper collar is the brass wiper squeals on the copper, my next fix is to remove the wiper and use a carbon brush setup.
The horn relay is probably black and round. It'll have these wires
Solid brown --- constant 12v
Light green --- key-on 12 volts (check fuses! #11 maybe?)
Purple/yellow --- 12v output to horns
Pink/black --- grounded when horn button is pressed
After checking fuses I'd use a jumper to apply 12v to the purple/yellow horn wires to see if the horns themselves are operational. If they are, make the other checks at the relay
VR
The reason your horn relay is not where shown on the diagram is that you have a slightly earlier car (same as me) and the relays are in a different position.
The horn relay is the middle one of the three. BUT: there is a fuse on the cars of our vintage which is marked on al the diagrams as controlling the aux fan, NOT he horn as well. This is the frontmost fuse under that black cover in your photo. This fuse ALSO fuses the horn. It is well worth removing it, trying a new fuse and cleaning up the terminals, as that might be enough on its own before doing the relay tests Doug advised. Those glass fuses often fail because the fuse wire comes unsoldered from the end cap, so it loks good, but isn't.
VR
The reason your horn relay is not where shown on the diagram is that you have a slightly earlier car (same as me) and the relays are in a different position.
The horn relay is the middle one of the three. BUT: there is a fuse on the cars of our vintage which is marked on al the diagrams as controlling the aux fan, NOT he horn as well. This is the frontmost fuse under that black cover in your photo. This fuse ALSO fuses the horn. It is well worth removing it, trying a new fuse and cleaning up the terminals, as that might be enough on its own before doing the relay tests Doug advised. Those glass fuses often fail because the fuse wire comes unsoldered from the end cap, so it loks good, but isn't.
Checked both: the fuse and the relay. In fact, I tried swapping/replacing both of them with units from the donor car. Still no go.
I also removed and checked the steering wheel horn pad. Springs and connectors appear to be in good shape.
Is there a way to check for circuit continuity at the steering wheel (with the horn pad removed) by jumping the connector(s)? The center one and one of the four small brass/copper buttons? If everything is working, should this generate a honk?
Is there a way to check for circuit continuity at the steering wheel (with the horn pad removed) by jumping the connector(s)? The center one and one of the four small brass/copper buttons? If everything is working, should this generate a honk?
I would proceed as follows:
using a test light, ignition on, engine NOT running, remove the feed connector (the live, not the earth) to the horns and ask a helper to press the horn and see if there is current at the horns. There probably will not be, but this is the starting point
if you did not do so, check if there is current at the relay high current brown wire
Also check, ignition on, if the light green wire to the relay has current all the time
Similarly asking a helper to press the horn button, check if the purple/black signal wire from the relay to the column goes live
If not, hot wire the signal wire to a 12 volt source and see if the horns will sound. If they do, you know it is in the signal wire circuit (ie the horn button to relay circuit)
next remove the shin trim under the dash under the column, wriggle in on your back and you should see two copper wipers touching the column metal. At least one of these should have a wire connected to it. Try earthing this wire and the horns should sound. If they do the trouble is in the column connections, either the wiper not making contact or something internal to the column (possible but unusual).
This is a start, report back with what you find. One extra question: is anything else not working, eg windscreen washers, aircon fans? If these things are not working, the trouble is in fuse no. 11 in the main fuse box.
The horn circuit wire colours should be: Horn wiper feed: purple with black tracer, this wire goes to the relay low current side; low current feed to the relay from fuse 11 light green. Power wire to the relay high current side brown (always live); power wire from the relay to the horns black with yellow trace.
greg
Last edited by Greg in France; 06-25-2017 at 01:35 PM.
using a test light, ignition on, engine NOT running, remove the feed connector (the live, not the earth) to the horns and ask a helper to press the horn and see if there is current at the horns. There probably will not be, but this is the starting point
Yes, did that. You were correct -- no current at the horns
if you did not do so, check if there is current at the relay high current brown wire
Checked that. Yes, there is a constant 12V at the brown wire into the relay
Also check, ignition on, if the light green wire to the relay has current all the time
Checked, and this is where I did not get the current! In fact, I tried checking all other wire connectors (ignition ON), and none (except thick brown constant 12V) had current. So, I think I need to figure out why I am not getting 12V at light green wire? This is the one coming from the fuse?
Similarly asking a helper to press the horn button, check if the purple/black signal wire from the relay to the column goes live
If not, hot wire the signal wire to a 12 volt source and see if the horns will sound. If they do, you know it is in the signal wire circuit (ie the horn button to relay circuit)
next remove the shin trim under the dash under the column, wriggle in on your back and you should see two copper wipers touching the column metal. At least one of these should have a wire connected to it. Try earthing this wire and the horns should sound. If they do the trouble is in the column connections, either the wiper not making contact or something internal to the column (possible but unusual).
This is a start, report back with what you find. One extra question: is anything else not working, eg windscreen washers, aircon fans? If these things are not working, the trouble is in fuse no. 11 in the main fuse box.
The horn circuit wire colours should be: Horn wiper feed: purple with black tracer, this wire goes to the relay low current side; low current feed to the relay from fuse 11 light green. Power wire to the relay high current side brown (always live); power wire from the relay to the horns black with yellow trace.
greg
V
If the other things on that green wire's fuse are live (is anything else not working, eg windscreen washers, aircon fans? If these things are not working, the trouble is in fuse no. 11 in the main fuse box) then the current that should be coming out of fuse 11 is definitely coming out!
Do this test: run a wire with 12 volts directly to the terminal on the horn relay that the green wire is connected to (eg take a feed off the coil positive, ignition on, just for this test). Then try the horn. If it works then you have a break in the green wire's low current 12v feed to the relay. Tracing that wire from the fuse box is not easy, but picking up a fused ignition controlled 12 volt feed is not hard. Post with what you find.
Greg
you have
Greg,
I realized that I was working with wrong relay. Per earlier suggestion, I was testing wire/connections to/from the 2nd relay (red relay.) However, I should have been testing the third relay (black one.)
The reason I am sure now is that it is black one is that when I jumped live feed with the Purple/Yellow wire (wire to the horns), the horn honked. So, this confirmed that the horn relay is the 3rd relay in that row (black one) and that the horns themselves are fine when they get the juice.
I then redid the tests:
>> check if there is current at the relay high current brown wire Yes, constant 12V at the brown wire
>>Also check, ignition on, if the light green wire to the relay has current all the time Yes, with ignition ON, light green wire has 12V
>>Similarly asking a helper to press the horn button, check if the purple/black signal wire from the relay to the column goes live No, when horn button is pressed (with ignition ON), purple/black wire does not go live
>>If not, hot wire the signal wire to a 12 volt source and see if the horns will sound. If they do, you know it is in the signal wire circuit (ie the horn button to relay circuit) Yes, horn is activated when purple/yellow wire to the horn is connected to 12V source
>>next remove the shin trim under the dash under the column, wriggle in on your back and you should see two copper wipers touching the column metal. At least one of these should have a wire connected to it. Try earthing this wire and the horns should sound. If they do the trouble is in the column connections, either the wiper not making contact or something internal to the column (possible but unusual).
I then removed the covers under the steering column, searching for the two copper wires. I did not see them. I made a picture. Where should these wires be located?
Ok, good so far.
The copper wiper is towards the bottom of the photo, in clear view, just under the car that goes across the photo. Find the purple/black wire and see where it is connected. Earthing this wire should make the horns sound. It should be connected to a copper wiper touching the column.
greg
Got it. For some reason I was looking for copper "wires". Upon re-reading, you clearly said copper wipers. My fault. Yep, they are clearly seen once the cover is removed. And the purple wire is indeed connected to the copper wiper.
Well, I finally found what the problem was. It was the faulty horn relay!
Ironically, this is the first item I started checking. But I initially selected the wrong one. I picked the red relay (2nd in the row of three), which was apparently not the horn relay. The horn relay is the black one (which is 3rd in the row of three). I tried swapping red relays (which obviously did not do anything to the horn), but then I moved to test connections and circuit continuity. (Which was great exercise, by the way! Thanks to Greg for step-by-step directions. I learned a lot by going through the tests.)
As a last resort (which should have been the first thing to do), I tried replacing the black horn relay with another one from the donor car. Even when not wires were connected I heard an encouraging sign: upon pressing the horn button I heard the relay click! (The old one did not click )
I quickly connected all wires and tried honking -- it worked! So, it was the faulty relay!
Thank you, Greg and Doug! Very satisfactory feeling of accomplishments! The car did not honk since the day I acquired her. But now she does!
Greg,
I have a similar problem as V1rok had described. After following some guidance from Doug I was able to determine my remaining issue is in that my horn sounds all the time. I bent the metal finger away from the steering column, but when I touch i press the metal arm against the brass ring it honks continuously, even with the horn pad off.
Any help would be appreciated
Jim Jam
I had the problem of continuous sounding horn. It ended up being the spring down inside the column continually shorting on the column. I posted a link earlier in this thread on how I repaired mine.
Warrjon
I read your earlier link, the repair you made seems to be the same issue I have. I will have to continue to read on how to remove the steering column and ignition.
As I am retired I have the time. I am learning as I go with this jaguar, and not sure how difficult a task it will be to remov the column.
Additional reading is in order for me to attempt this disassembly and repair.
I appreciate your response
Will let you know how it goes
JimJam
06-24-2017, 05:58 PM
Troubleshooting Horn (not honking)
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