Headlight and tail light not working ? GT 750

[MR X]

Hi Guys ,
Question on my GT -750
My headlight and tailight are not working when switched to the ON position .
Also the HI beam indicator is on even if it is in the LO beam position .
Brake lights work fine.
All other lights ./ etc work fine as well .

Any ideas ??
Thanks

[oldjapanesebikes]

What year of GT750 ?

[MR X]

1977 -GT 750

[oldjapanesebikes]

Starting in late 1976 and for the 1977 model year, the on/off switch is locked out and the lights are always on - you just have a choice of high/low beam. Sounds as if either the switch has a problem, or the wiring has been played with in the headlamp bucket. Elsewhere on this board (actually I think in this forum thread) is a really good wiring diagram with the colours clearly shown - take a look at that and double check the connection in the bucket. If you have a meter, also double check that your switch is actually working.

[jabcb]

Wiring diagrams for lots of bikes: http://smokeriders.com/Technical/wiring ... grams.html

Here is one scenario with two separate problems.

If the headlight ground is bad but instrument light ground is ok, then:
1) on high beam: yellow wire is hot, high beam indicator light is on, headlight doesn't work
2) on low beam: white wire is hot, power goes from white wire thru low beam wire thru high beam wire to yellow wire & high beam indicator light is on. Since indicator light has much higher resistance than headlight, you can see indicator lit up but not headlight.
Check headlight ground.

Then the taillight has an unrelated problem. Working brake light would indicate ground is ok.
Check voltage at taillight when the lights are on. Check bulb.