Understanding rear light wiring

[Brett Hogg]

73Z28, I am having trouble understanding the rear light wiring. Outer lights(Brake/Tail/Indicator) Inner (back up) How does the wiring work, 18 BRN is Tail light, 16 DK Green and 16 YEL would be indicators, how does system make brake lights work as the only other wire s 18 BLK -150 Earth, am i missing something?, My lights work, but i want to do a subtle change wand make a new harness.

 

[Gary S]

Signals work with 16 DK GR and 16 YEL by breaking and making power to that filament. Brakes work on the same lines. When brakes are applied, both lines have power the the brake/signal lights are on. If a turn signal is applied at that point, that side will be switched to OFF/ON sequence as the light was on.
If turn signal is applied with brake off, the sequence becomes ON/OFF as the light was off when signal was applied.
Because the two functions share a single filament, you can't have both brake and 4 way flashers at the same time, but for directional signalling, it can happen because only one side is used at a time.

 

[Brett Hogg]

Gary, thanks. So the brake lights use the signal wires. I have been trying to follow the wiring diagram to locate how this works. Guess that rules out my thoughts of modification to my indicator circuit.