hello guys, my name is calum and i have just bought a 1976 Yamaha dt250
im having trouble with all the lights, nothing is working no head light, indicators or brake lights etc.

does anyone have any information that could help?

In the Tech Library you will probably be able to find a wiring diagram which is a great place to start.

Not 100% sure on your particular model but in general these bikes have 3 separate circuits.

Magneto ignition is completely independent of the battery and lighting circuits. All you need is a wire, usually black, to the coil and a ground thru the key to shut it off.

The headlight runs on AC and that's the 2nd circuit unconnected to all the rest.

3rd is the charging system to keep the battery up for the lights and on my RT1 there are 2 variations. One is daytime charging. The other is night. Not sure if your 76 is the same but hopefully you've got the general idea!

Good info pntrbl... if you count both the "day and night" charging that's actually 4 systems/circuits!

Battery is required for some of the lights like the brake light and tail light... The headlight and some of the indicators run on AC and will only be on with the engine running...

Good battery? Check the fuse first...

Next thing I would check is the bulbs. 1976 is around the time Yamaha added a voltage regulator so you should have one. The system is balanced and without a regulator it's very common to blow bulbs by running without a battery and/or after one of the bulbs blows. Not as common with a regulator but can still happen.

Then check the switches/wiring/grounds.

How do I make a connection to get my headlight and tail light to work?

Hey I have the same problem, I need some help getting the lights on my bike working. I have a 1978 enduro dt 250.

Easiest way would be to unplug the magneto wiring harness from the main wiring loom of the bike. Get a 6v battery (you can even just put a few C or D batteries together if you have to) and hook it up to the yellow wire w/ white stripe on the bike's wiring harness, then ground the battery to the frame. If you have the day/night switch on the left controls, you should be able to see the headlight and tail light working just by doing this. You don't even need the key to be on! The headlight system is 100% separate from the keyed DC system. It could only produce electricity w/ the engine spinning, so there was no need to run it through the key.
IF you can get a light to light up by doing this, then you're not even getting voltage out of the lighting coil. If you can't get a bulb to light, the very next step would be to check the bulbs themselves. If those are good and you still don't have lights, we can start removing point of failure one at at time. Having JUST finished redoing 100% of the wiring on my 1974 250 (because I converted to 12v), the wires and circuits are still fairly fresh in my mind. It seems like a complex nightmare, but it's really not all that hard to troubleshoot if you have a voltmeter and 6v battery handy.

On the headlight switch ,find the wire to lights On/off , [ usually blue/white striped, or Yellow], trace it to the headlight, [ unplug it, and plug in a new wire ], make the wire long enuff to go down under the Fueltank to the rectifier. join it to the White spade/wire on rectifier,. == and you now have A/C lighting, [engine running[,

If it's a US model, by law there is no headlight switch starting in 1976. Headlight comes on when engine starts.

Most of the other lights need a good 6v battery to be installed. Second thing is check fuse and connections near battery.

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glad to come across this. I recently bought a brand new 12v harness of Sparck Moto for my 1974 Yamaha DT250. Still having a lot of trouble getting the headlight on. Just gotta keep trying!

I rebuilt the whole damn bike and it runs great. However the lights... frustrates as hell with them. Already blown two headlights and indicators, new rectifier, new flasher, new battery, all new brake lights and blinkers and it still just won’t work. Uaggggggh