Originally Posted by Snowflake1
I have a problem with the left rear stop light. Turn signals are working as is the lights. I checked the dual filament bulbs and the ground of the Left rear light casing and all is ok except the left rear stop light will not light. Right side and the central raised stoplight all work fine
Are there any diodes involved in this type of circuit ? Why would the right and center work, but not the left?
Would appreciate any advice or tips on how to fix this problem
Thanks , Gerry
It would be nice to know what year/make/model/engine coach you have. Others may have the same coach and have experienced the same problem. Your problem could be something simple or, might be a tough one to analyze. You state you've checked the filaments in your dual filament bulb, correct? Well, just for grins, switch bulbs, from right to left and see what happens. Most likely nothing and the same thing will appear.
Since you say you have dual filaments, in one bulb, I'm presupposing that you do NOT have AMBER turn signals. I just like to be clear on things like this. So, typically, in the olden days, there were basically three wires to those type of tail lights. One for running lights, (usually brown), one for brake and turn (usually green or yellow, depending on which side) and a ground. Not, nothing is gospel here. There could be all kinds of colors out there for the same purpose.
But, If you're receiving a turn signal, to both sides, and no issues there, then the wiring to the bulbs, on both sides, should, I say SHOULD be fine. And, as has been stated, typically, the wiring for brake/turn filaments, goes through your turn signal apparatus in the steering wheel. When your turn signal arm is in the neutral position, and you hit the brake pedal, the brake switch sends a signal, through the turn mechanism in the steering wheel and, both sides receive the signal and, both right and left filaments light up.
But, when the turn signal arm is ratcheted either left or right, and the brakes are applied, only half that brake light signal is seen, at the rear. The other half sees a signal that's being routed through your turn signal flasher and, to the appropriate rear bulb (front too).
So, this will be interesting to see just what the problem is. Let us know if and when you find out.