Was wondering if someone can assist me with the wiring of a third brake light on an 85 Chevy G20 Sportsvan.
Do I need to run a wire directly from the brake switch.

Without checking I tied into a wire at the right rear brake light. But it turns out it also controls the turn signal.
So now when the right turn signal is on, the third brake light blinks and the left brake light won't work.

So much for an easy fix to being noticed when I go to stop!

 

Not sure about 85, but the same bulb did both the brake light as well as the turn signal light. If this is the case then you will need to run a wire directly from the brake switch. Just see if the same bulb lights for the turn signal and the brake light.

 

Yes, it is the same bulb, so I will have to run a new wire back from the brake switch I suppose.
Was hoping they might have run separate wires back to the rear of the van for turn and brake lights, but I guess not, would have been less wires for them to tie them together up front and only run one wire back.

Thanks for the reply.