Please help me if you can. If I understood the internal workings of a 1157
bulb..I'd feel better about this issue..

I have a trailer with .....wired ground leads with white wire ground to the
lights individually (I moved my trailer lights to the top of PVC uprights,
and since PVC doesn't carry electricity, I added separate wired grounds)..
That part seems to work OK since I have working stop and turn lights on both
sides. I don't have parking lights.... Yellow and brown to one side, green
and brown to the other side... All SHOULD work normally.

The replacement rear light has.... RED and BLACK wires coming out of it.
It IS designed for stop/parking/turn operation. I added a white ground wire
to the base of each unit and connected that back to the white wire ground
from the wire harness. . I ASSUMED that the BLACK wire would match the
BROWN wire and I wired accordingly... My issue is the lack of parking
lights.

After thinking about things for a while, I wondered if the BLACK should be
connected to the green or yellow wire .... and the RED wire should be
attached to the BROWN lead???

A little further confusing thoughts...that the colors, by themselves,
shouldn't mean anything...one filament should be on "all of the time" ( when
the parking lights are set to ON)..and the other filament should be on/off
based on input from the relay on the left or right sides.

Why, then, doesn't the "wrong" connected filament at least "glow" when I
may have mistakenly reversed the wiring??? I then wondered if the filament
on the BRAKE/TURN INDICATOR side is so much bigger..that it doesn't reflect
any "glow" even though current is flowing to it..

I'm puzzled. I hope the above description comes close to explaining the
issues and my thoughts about them...Thanks for any observations and or help.

p.s I know I could just switch the two leads and I probably will do that
the next time I go to the boat...but the issue of a non-glowing filament on
....even the wrong side... still puzzles me.
thanks, RichG TX/IL