Jaguar Repair: 84 xj6 Horn beeps when I brake, fuel gauge, horn button

Question
QUESTION: Hi Howard,
Yesterday a local mechanic spent the day working on my 84 xj6. The problems he looked at were the speedometer/odometer not working and the fuel gauge which he fixed. I drove it last night and when I braked hard the horn beeped. I drove it again today and had the same problem.  My mechanic is returning next week to replace the speedometer transducer and fix my moonroof and rear electric window so any advice that I can pass on will be much appreciated.
John

ANSWER: Sorry John, the fact that the horn beeps when braking hard does not pinpoint the problem at all. You (or your mechanic) just needs to take a wiring diagram and start tracing the wiring with a test light.
Howard

---------- FOLLOW-UP ----------

QUESTION: Thank you for your reply. To fix the problem with the horn beeping when I brake - do you mean that I should I take a wiring diagram and start tracing the wiring with a test light. Thanks.


Answer
Yes, as you obviously have short in the horn circuit and the only way I know of to find a short in a circuit is to start tracing that circuit. I would start at the horn button and work my way towards the horn relay (located under the hood up in the right front) The button to horn relay wire is about the only wire that can trigger the relay to beep the horn. You may try bumping the relay itself to see if the relay could be coming apart inside beeping the horn but that and the wire to the horn button are the only possibilities. To start at the horn button you will need to remove the large pad held on by screws into the back of the steering wheel.
Howard