Can somebody please help me with a electrical fault?

[joedoh]

Originally Posted by fleetsidelarry

good grounding is vital and should be verified, I agree completely. just, in this case, since the same wire and bulb filament works while flashing but not during braking, it didn't seem likely to be a grounding problem.

unless the ground for those lights is being backfed through one of the other circuits such as the brake wire. chased this a hundred times on non-working old GM cruise controls, where by design it gets its operating ground through the ground of the taillights (thats why it turned off when you tapped the brake, no complicated system there). holds enough current capability to turn on a parking light or flasher and goes away when the brake is used.