Went to get my car inspected. Of all things, the horn didn't work . Fuse is okay. But don't know where to check next. I see a horn next to the battery, but I believe that would be for the after-market alarm.

Any suggestions where to start?

📯

TIA

ken

 

Hello, Ken,
Yes, the horn next to the battery is an alarm. It was the fashion to install one in that era.

Try this first as it's the easiest thing to "fix"; push on the horn pad vigorously,rocking it around while moving the wheel and see if that fixes it. If it does, then the contact under the pad is dirty (not surprising after all these decades).

To clean that you need to remove the pad by 2 screws on the back of the wheel. There you'll find a large nylon nut, usually only finger tight but might need a socket to grasp it.

That is the pad end of a long brass tube about 5 inches long with another nylon sleeve on the bottom end, that fits over another contact deep in the column.


I would guess your problem is in this probe somewhere. Doubtless some cleaning will fix your problem
(';')

 

On the XJS there is an unidentified fuse in the horn circuit. If you have an auxiliary electric fan (the XJS does) the fuse under the bonnet that does the electric fan ALSO does the horn, in addition to the main fuse block horn fuse.

 

First things first: there are always two horns on a Jaguar (one high and one low tone). Both horns on the Series III cars are located behind the centre of the front bumper,- very obvious if you look under the bumper from the front. Verify that the electrical connections are clean and secure. And then, the fuse. Do this before dealing with the steering wheel horn connections.

 

While under the front bumper get out your 12v test light and see if when you push the horn button (with the key in the "on" position) you are getting power.

 

And the fuse for the horns is an in-line fuse, found near the battery box (at least on the LHD cars). This is very often the culprit. On the very last cars (1991/92) the battery was moved to the trunk to allow space for the ABS unit…I think the horn fuse remained in relatively the same position as earlier.

 

STOP PRESS ! Remembered at 3 AM -…the horn fuse is located ABOVE the battery on the firewall/bulkhead. Not the best place for an in-line fuse, is it? Thus the common fuse failures.

 

Well, I looked under the bonnet, but, stupid me, I touched something that fell apart. There was a wire with an inline fuse attached to the frame behind the battery. When I touched it, the plastic cap crumbled into pieces:



I couldn't tell what size fuse it is, or if it is blown or not. It is too old. But I did check it with an ohmmeter, and that showed less than 10 Ω.

So, does anybody know what this is for? Maybe for the horn?

 

Yes, that is the fuse holder/wiring for the horn. Replace the holder and put a new 10a fuse in it. Use an SAE standard fuse such as BUSS with this rating. British and SAE fuse ratings are not identical.

Dave

 

disconnect the positive battery cable before replacing the fuse holder. Fuse holders are available at auto parts stores. Get one with the same gage wires. The original brown wire is quite thick. I forget its gage. Do it right to prevent any electrical accident but if you don't think you can do a proper job, take it to someone who will. The fuse is 35 amps.

 

Jose, I think the 35a fuse you indicate in your post is located in the main fuse block, #11. That fuse is used just for one side of the latch in the horn relay as well as a few other items. The power for the horns come directly from the battery and S57 calls for a Lucas 17a fuse. I think a 10a SAE is roughly equivalent.

Dave

 

Dave you.are right but my fuse holder has a 35 amp Lucas fuse still unblown. Maybe I got tired of blowing the fuse and stuck a 35 amp in there. NOTE: it's the LUCAS 35 amp which when you roll it it says 15 continuous amps on the other side. ??