Horn cutting out engine?

Hello guys , got a problem with the horn ,if presses and held in the sounds but cuts the engine?

If you just do a quick tap of the horn engines runs?

Took off the horns cleaned all conections a brackets if I don't bolt them back to the car and leave on the garage floor connected and sound the horn everything works ok

But when I bolt the horns back on the car they cut the engine ?

Any help would be much appreciated

Regards Dirk

very, very odd. do they work ok if you bolt them back on with plastic washers to stop the bracket from earthing to the chassis? if so, something very strange is happening here. seems something is earthing via the horns, which i didnt think was actually possible as far as i know the horn body doesnt have an earth path anywhere, and besides i cant see how this would even do anything.

i think its best to start by checkign the horn wiring, make sure the earth from the steering rack to chassis is clean, make sure the horn relay is ok.

then look at your engine earths, in particular the gearbox earth as where connects to the top gearbox bracket is a poor earth point

Thanks for your reply John , yes it's doing my head in a bit ,I will try what you suggested but it's strange, there is a immobiliser in the car (wipac) ,but I dont think that would cause to much drain on the car ,also the reversing light don't work ,put a fuse in put it in reverse and it blew ?

I will check the steering rack earth  and try a spacer on the horn bracket   and  i will let you know how I get on

Thankyou very much Dirk

Hello john , got a bit further with the fault finding,

when pushing the horn ,it de-energizes the fuel relay thats why the car is cutting out when held in ,(the fuel relay clicking eraticaly when horn operated)

also lost supply to fuse No.6 (interior lights,radio, clock )

any advice on what to do next ,guys

thankyou for your help best regards dirk

ok the horn thing seems to have been a red herring. dressed in a silly suit, doing a funny walk!

Sounds like you have a fusebox supply or earth fault, what type of fusebox is it? I'm guessing its the ceramic fusebox from fuse 6 supplying the radio.

fuse 6 is fed from the permanent live feed from the battery, as is the fuel pump relay. this would suggest to me either the main live feed to the fusebox is bad either at the fusebox or the battery, easy to check this its a chunky red wire at the battery, and it runs to a massive spade plug on the back of the fusebox.

The main fusebox earth comes from D/11, which runs to a jumper block on the lighting loom earth which comes from the fusebox. you cant miss it theres a large white multi spade point. D/11 runs to this, as do a few other earths one comes from the earth 'claw' above the fusebox.

while you're up there, check the condition of the fusebox if there is any damp or corroded areas then you'll probably need to replace it, but make sure you cure the leaks first!

the trouble is, fuse 6 i dont think would effect the horn and fuel pump relay, unless the problem there also was effecting the chunky red main live feed into the ignition switch. this also runs to a large spade terminal near the live input from the battery, so check this over the same way you checked the battery live.

It may just be the ign switch itself is to blame, to rule that out pop the ign switch plug off and bridge a chunky wire between the red and black wires. if that cures the horn problem then get a new ignition switch

Ok John will try this the weekend I will let know how I get on