MG Car Repair/horn problem on 1970 MGB Mk 2
QUESTION: Hi Barrie,
I have no power at the horn, fuses ok so maybe it's the pencil switch in the steering column. I have a new one but I can't remove the old one, I've tried to pull it out but I don't want to use too much force. Any advice will be much appreciated. My car was built in the UK.
ANSWER: Hi Graham
The horns on your MGB are not powered through the horn push. They should be permanently live and the horn push provides an earth when you press it.
First check that you have 12 volts at the purple terminal on each horn. If not, you have a wiring problem. Does the courtesy light work when you open the door? It uses the same fuse.
Next attach a temporary wire to one of the purple+black wires on either horn and momentarily touch the other end to earth. The horns should both work. If not, you either have two faulty horns (unlikely), or a wiring problem at the front of the car. The bullet terminals often corrode so check them out first.
If all the above are OK then your problem lies in the area of the horn push. The most common problem is the rubbing earth connection between horn push and the steering column. The pad wears out and the spring loses its tension.
Let me know how you get on.
---------- FOLLOW-UP ----------
QUESTION: Hi Barrie,
Thanks very much for your advice it was very helpful.Power is ok to the horn but there is an intermittent problem with the earth at the pencil connection, I have tested it with horn button removed so it's not that.
I have a new pencil but i'm still cocerned about pulling the old one out.
The new one seems to be a later design & the spring is internal, the old one has an open spring at the connection end. Any ideas?
Hi Graham. You have successfully narrowed down the problem to the horn push area. If you need the original plastic pencil I am sure I have one in my odds-and-ends box. It is only a spring-loaded electrical connector and it should pull straight out without any effort. I don't see that there is much to go wrong with it so long as it still extends under the pressure of the internal spring.
Next I recommend that you remove the steering wheel and inspect the slip ring and the spring-loaded connector that rubs against it. As I said in my previous reply, they do cause problems when the rubbing connector wears out or the spring material loses its tension.
Alternatively, you could bypass the problem altogether by converting the turn indicator lever to include a horn push. I have done several conversions like that. It gets rid of the problem forever.