Another turn signal/break light wiring prob.

I am wiring my car from scratch and have looked and read everything. I am testing as I wire, I have a Signal-stat 400 and will be using dual filliment bulbs out back, I have run separte wires for left, right, and tail lights to back.
With the Signal-Stat 400 you can't run the break lights through it, but I read somewere that you can get a trailer light adaptor that adds the break light into the turn signal wires, so I installed one. The input wires are R-turn, L-turn, break, tail light, and ground. The outputs are R-turn/break , L-turn/break, tail light, and ground.
The problem now is the turn signals and breaks work separtly but when you use booth at the same time, i only get break on one side and nothing on the other. I though I had it figured out. Bad switch or bad trailer adaptor?

 

Pull the brake light wire off the brake switch and both the turn lights off the turn signal switch. You will have to run a specific wire for the brake lights to the back of your car, split it to both sides of the car and then you will will need a brake light specific element or bulb. Gene

 

The 400 doesn't support combined brake turn signals, unless you understand diodes you will need separate brake light bulbs or a 900 type.

jm2c

 

I think the Signal Stat 900 has the wiring for brake lights.

 

Since the turn and brake circuits work separately and it only malfunctions when the trailer converter is supposed to be doing it's magic, I would suspect the converter is bad. We tried to use those trailer converters when putting U.S. truck bodies on import trucks in the '70's. At that time the converters seemed to be poor quality, with many failures at install and also not much of a service life.