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Wiring problems with my 1977 CB750F1

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Stewartgh:
Hi would appreciate anyones help here, I am going mad, I have 2 problems, first is that my tail light does not work, brake light is fine, and tail light works when ignition switch is set to park so I assume buld is OK as park is using the less bright filament as would the tail light, but not in run with 'P' or 'H' position selector switch on, the other problem is the sidelight in the headlamp is not working, same situation, when ignition switch is set to park it works, but not in side light mode!!!
I have found plenty of wiring diagrams but none show the sidelight in the headlamp unit or the separation of the tail and brake light. Any help would be appreciated.
In my headlight I have 1 large buld in the centre, which has 2 filaments, both are working for high and low beam, then there is another small bulb  below the larger one which has 1 wire going to the centre and then a ground, this is what I am refering to as the side light, and this is the one which comes on when the ignition key is in the park position, on the handle bar switch I have 2 positions one is labeled 'P' and the switch lever goes up slightly in this position into an inset part of the groove, and the other position is 'H', which assume to mean 'Headlight'. I took the bike for an MOT recently and the guy at the garage told me that the 'P' switch position should turn on the side lights, (the smaller bulb below the main one in the headlight). this is not working, and in fact to rear light does not come on in that position either, but it is also not working in the main position so that could be a red herring. ???

Spitfire:
Had the same problem with my back light, it is a question of following the wires back, no magic bullet, I think in the end I switched the "live" in the headlamp to the old indicator beeper feed. In the end it was a bad connection in the fuse box causing the problem.
The P switch is indeed for the Parking (side) lights.
I'll PM you the wiring diagram from my handbook (1976 CB750F1).

Cheers

Den

Yoshi823:
Faulty right hand switchgear suspected.

The brown wire that feeds the tail light bulb, the pilot light in the headlamp & the lights in the speedo/tacho are all supplied from the right hand switchgear when the ignition key is in the 'ON' position. The reason that the keyed switch illuminates the tail bulb & the pilot bulb when in 'P' or 'PARK' is because it connects the red to the brown for those circuits, bypassing the right hand switchgear. I would check the brown wire coming out of the switchgear for +12v when selected with the ignition in the 'ON' position. The +12v goes in on the black wire which is the regulated +12v, as against the unregulated +12v which is from the battery via the red wire.

Stewartgh:
Thanks guys, I am off to take a look now with your comments in mind, and thanks a bunch for the schematic Dan, thats the best one i have seen..... will update later.

Stewartgh:
OK More descoveries, brown and black in the RH Switch both have 12v all the time, until I switch ingnitiotn to park position at which point the brown loses the 12v, I have dismantled the switch cleaned and reassembled, and when I check the switch operation out with the DVM with no power switched on at ignition all checks out perfectly so I am pretty confidant the switch is good... also I noticed that when the RH Switch is in P position if I turn the indicators on the P lamp in the headlight flashes in time with the indidcators!!! ???

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