Talk Morgan Forums Thread Like Summary - 3.7 Roadster

Yesterday I discovered the horn(s) weren't working on my 3.7 Roadster. I have now removed the horn push in the centre of the MotoLita steering wheel - cleaned up the copper contact strip and tested the circuit when the button is pressed in, which is all working. I have also removed the 2 horns, cleaned up the connectors and tested each one individually - both working fine.

When the engine is running they work as they should, however if I have the ignition on, but no engine running, they don't work. I can hear them trying to make a sound, but not properly. Are the horns meant to work with just the ignition on?

I suspect there may be a corroded earth somewhere? I can see on the Roadster circuit diagram that there is a wire that comes off the junction of the horn wiring to a chassis earth with a 5mm eyelet, but I can't locate it. I have tried tracing the wiring from the horns right back to the fuse box, with no luck. Does anyone know where this earth is located?

Thanks in anticipation.

Which is why mine were quickly replaced by Nauitilus Stebel air horns. Two horns and compressor integrated into one unit.



Having said that my original pair are now doing sterling service mounted high up out of the crud on my Series Land Rover.

To be clear the horns should most definately work with engine not running providing key is in auxiliary or ignition on position.

The slip ring pickup brass strip connection to light switch is difficult to describe but have found this image showing in two aspects the rear of column switch housing.



The two light switch connector receptacles can be seen on the right of upper image. You can also see the slip ring brass strip male spade connector in two aspects, adjacent to lower right hand screw. When removing light switch the matching female brass strip connection should be carefully slid off and brass strip removed before light switch can be slid out sideways (after removing two securing screws). I mention this because a high resistance connection at any of the five connection points in this area could individually or collectively cause enough volt drop to present your issue.

The horns, high and low are interlinked and have two electrical connections. Disconnect the wiring and using your meter check to see what's happening and are you sure both are working. If it sounds a bit weak then only one is functioning, if it blows your socks off then both are chirping. check those 4 electrical connectors and as Richard said the fuse. vibration from a running engine might be aiding a dodgy connection and the fuses and relays are notorious for slight corrosion. Whatever it is its going to be simple. As far as I remember there's now relay in the circuit.

Thanks Sewin - I have cleaned the copper contact on the steering wheel hub,changed the fuse, cleaned all the horn connectors (4) and the horns now work just fine. They still struggle when the engine isn't running, but as I am unlikely to use the horn without the engine running I am not going to investigate any further. It may be a poor earth but that will mean accessing the light switch in the steering column, which I will do if I have further problems.

Looking at the relays (and diagram in the box) there doesn't seem to be a horn relay.