Let's see if I can describe this without totally confusing things.
The center yellow in the pic comes from the GI lamp socket between the G and the U, from the side closest to the car belt. another yellow comes off the other side of that socket (seen in the picture soldered to the exposed wire and going into the plastic just below the right bumper).

That exposed wire goes one way to the bottom of the bumper near the belt where it connects to the bumper light and the other way to the bottom of the bumper light not in the picture. The flat wire looks kinda like a sideways T and connects to the top of each bumper light.
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