lights dim when braking

[tophat Q]

Here is my problem.....

I have an 89 zx750f that I am building and trying to work the bugs out of.

When I press the brake lever my front light and brake light both dim. I do not have any other lights (turn signals or running lights on the bike) so I do not have a reference for if that would also happen to them. I have tried reversing the wires to the brake light, but when I do this I pop fuses.

Thoughts, suggestions?

 

[D....]

Can you run a temporary wire to bypass the one in the harness for testing? This would confirm or rule out a shorted or chafed wire in the harness.

 

[Sonreir]

Sounds like your brake switch is grounding.

 

[D....]

I agree Sonreir. It is just strange that the fuse does not pop unless the leads have been switched. I can only assume that the surge from the immediate illumination of both elements blows the fuse while momentary braking is not enough. Gremlins??

 

[Bert Jan]

is it front or rear brake switch? De-attach switch from frame (no ground) and try again. If it works, Sonreir is right. If not, your harness is broken.