Topic: Electical gremlins help required!

[stewonepot]

Hi All,
I have a cb750f1 which started life in Germany , it now lives with me in southern Spain.
My problem is with the horn. When the horn/pass button is pressed for the horn function the horn will click and the side lights front/rear will light.When the side lights are on the horn will not even click. Possible bad earth? I have gone through the connections in the headlight bucket and in the junction box on the frame. many thanks in advance
Regards Stew.

[madmtnmotors]

Don't forget to test the horn. Connect the horn to a 12V power source and verify that the horn actually works first, then work your way back through the harness from there. While you're checking the horn, go ahead and hook a voltmeter to the horn leads (in the harness) and see what you get there when the horn button is pressed.

[stewonepot]

Thanks for the response , will look again in the morning 20.41 here at the moment.The bit i find strange is the side lights coming on.
kind regards Stew.

[scottly]

The lights coming on might well be related to a poor earth: on the 750k (not sure if the wiring is the same on Fs, much less German models) the black wire to the horn is always "hot" when the ignition switch is on. The light green(?) wire to the horn is switched to earth when the horn button is depressed. Hope that helps..

[stewonepot]

Hi all
Problem solved. After much studying of the old faded wiring diagram which came with the bike , it seems that one terminal on the horn must go directly to earth,and not into the loom
as it was and sending the wrong messages to the side lights.Many thanks to all of the replies . This is a brilliant forum.
kind regards Stew.