When the brake light turns on, the headlight shuts off, wtf?

Hi guys,

So as the title says, when my Peugeot's brake light is on, the headlight shuts off. Otherwise everything seems fine, though the lights are a bit dimmer than I'd like while the bike is idling. Also, the brake light doesn't work when the bike is at low RPM's (basically idling).

Electrical work is not exactly my forte, so any help is appreciated.

I'm wondering if this may be a grounding problem with the handlebar controls.

I've attached a wiring schematic I've made for my bike. Most of the harness is NOS peugeot, just modified for a cdi.

Thx a ton!!

103 DUCATI WIRING (1).jpg

Re: When the brake light turns on, the headlight shuts off, wtf?

Bad ground connection(s).

Re: When the brake light turns on, the headlight shuts off, wtf?

might be wrong wattage too, if they're on the same line in parallel, too low watage just acts like open to ground out the power

Re: When the brake light turns on, the headlight shuts off, wtf?

Something is not right with either your diagram or the wiring. There is no supply from the regulator output to the stoplight circuit. Also the brake light switches should be in parallel so that either brake will switch them on. as they are (in series) you would have to have both brake levers pulled to operate the light. I will try and redraw the diagram as it should be if you think it might help?

103 DUCATI WIRING (1)a.jpg

Re: When the brake light turns on, the headlight shuts off, wtf?

Thanks for the reply!

I haven't really modified the brake light circuit at all from the stock harness, so I'm not sure how it could be wrong, but like I said I'm not good with wiring.

If you see a problem with my harness, I'd be happy to see any corrections. I'm up to at least try anything that might fix the issues.

Here's the stock harness diagram that I am working from, I tried to modify it as little as possible to avoid issues like this.

I have some time tomorrow. I'm going to go through and check my grounds to see if that clears things up, too

stock_103_wiring.png

Re: When the brake light turns on, the headlight shuts off, wtf?

Screenshot_2019-08-12-22-57-36.png
Screenshot_2019-08-12-23-01-15.png

Re: When the brake light turns on, the headlight shuts off, wtf?

liveevil's modifications to the diagram are correct. either/or brake switch would illuminate the bulb. the mass of unnecessary ground connections erased.

Re: When the brake light turns on, the headlight shuts off, wtf?

> Adrian Salter Wrote:

> -------------------------------------------------------

> liveevil's modifications to the diagram are correct. either/or brake

> switch would illuminate the bulb. the mass of unnecessary ground

> connections erased.

Forgot to mention the diagram shows normally closed switches. It would need normally open switches with the changes I made. Swithes come both ways and can be tested with a muiltimeter.

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