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MG MGB Technical - Horn stopped working

Sorry, a really novice question but my horn has packed up. Any suggestions? Wiring seems to be ok and no signs of a busted fuse - have I missed something even more simple?
Edward Sanderson

Check for bad earths. Check the horn push, too.

Tim.
Tim Jenner

Pop the horn Button on the steering wheel off and pull the spring plunger out and have a look for corrosion. Clean it up and re-install..,maybe it will work for you.
Eric Willis

The horn is wired "hot", it has 12V on it continuously (purple wire). When the horn push is depressed it completes the earth/ground in the circuit (purple/black wire). Horn problems are normally the result of bad earths.
Paul K

Put a voltmeter on the purple and press the horn button, then do the same on the purple/black. If you don't see 12v on the purple, or it goes when the button is pushed, you have a bad connection back through the fuse which is the bottom one. If the purple/black doesn't start off at 12v the horn is bad. If it drops to 0v but doesn't sound again the horn is bad. If it doesn't drop to 0v when the button is pushed the circuit back through the horn push to the column ground is bad. Collapsible columns often have difficulty getting a ground, I have fitted a relay to get round the problem, others have suggested a braided cable between body and column.
Paul Hunt

Pull of the horn button and pull out the plunger. Make sure it has continuity. Next take some sand paper and scuff both ends of it. Do the same to the horn button and the round copper piece it connects too. I have found most problem lie here as the pieces glaze when not used and tend to stop continuity.
J Arthurs

Edward,

Each horn has a lock-nut and screw which are used to tune or set the tone located on top of body (of the horn itself). If these go badly out of adjustment the horns will make very little or no sound. If you have confirmed that the horns are getting properly energized, try adjusting each horn by backing off the locknut and then turning in (or out) the screw while an assistant presses the horn push. I had this happen once and this adjustment brought them back 100%.
Cliff Maddox

This thread was discussed between 15/07/2002 and 16/07/2002

MG MGB Technical index

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