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DT175 MX 1980 - Lighting Issue

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Hi.  Seems I'm only ever seeking help/advice rather than giving so here goes;

Haven't used the bike for many months, (charge it every couple of weeks) took it out today but have got no headlight or side light and no rear light. Brake light works fine front and back brake. Hopeless at electrics so where's best to start.

Started first kick by the way..

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Hi Rick, You say you're hopeless at electrics! so don't be offended if i say have you checked the bulbs?

The DT has two circuits. The battery powers the tail/brake light, side light, indicators and horn. Meanwhile The magneto/generator ONLY powers the headlight bulb.  The headlight is on a DIFFERENT circuit to all the other bulbs.

Tracing faults is a process of elimination. The fact you have a working brake light shows there is power from the battery. Therefore the fuse must be intact and by default the earth for that bulb must also be intact. (The brake and tail light bulb shares the same earth)

The rear bulb may have a damaged tail light filament, incidentally just looking at a filament is not enough to say it's intact. Sometimes it may visually appear to be intact but may not work. It's easy to check bulbs with a piece of wire and the battery. Explaining how to do it..... well heres a video on you tube

Substitute your battery for the one in the video and touch the contacts on the bottom of the bulb separately to test them. One does work (you already know this because you said the brake light works) which means if you can't get either to work you're not doing it right. Equally, if both filaments work then the fault lies in the wiring circuit. You can test ALL your bulbs first this way to see if they are the cause and replace them accordingly.

The next part will be tracing the fault in the wiring if ALL the bulbs work using the above method.

Hope this helps. Let us know how you get on.

Edited by NE0

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