Quote:
Originally Posted by DanEC
After reflecting some more on the wiring diagram I'm backing off on the turn signal flasher. It feeds the turn signal power through a common lead so there isn't any reason it would work in one direction and not the other. That leads me to the turn signal unit. I guess I will resume testing around it later today. Probably feed it 12V power as suggested and try switching the L and R rear light leads to see if the symptoms switch sides also
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No, don't test the relay by switching the left and right inputs. That might actually mask the true problem. You should test the relay by disconnecting the three inputs and by first applying a clean 12v to each of the two side inputs, then combining a side with a feed to the middle "brake light" feed. You see, the relay is just an "exclusive or" logic circuit. Kind of like the three way switches in your kitchen. Each rear light has two "inputs." One input is from the turn signal, the other from the brake light. If you have 12v coming from only ONE of these, the relay will light the bulb. But if you have 12v coming from BOTH inputs, the relay will not light the bulb. In a properly running system you can see this by turning the car on, then putting the left turn signal on. The green dash light and rear turn signal will flash in unison. They are both "in phase" with one another. But if you then push the brake pedal down, the flashing will switch out of phase. The rear turn light will flash when the green dash light is dark, and
vice versa. So, do not test the relay by just switching the inputs (of which both may be faulty). You must use known-to-be-good, clean inputs, to test it.