Passenger taillight issues.

For some time now my passenger taillight has been dim, perhaps only putting out half the light as the driver's side. I have LED sequential taillights back there.

I have a new taillight harness with new lamp pigtails, new lamp buckets, and even a new turn signal switch (replaced twice to make sure), new brake light switch, and a new headlight switch.

Here's a mores serious problem that I found just today: the passenger brake light comes on (dim) when I depress the brake pedal when the car is off, but goes out when the car is running. Having the headlights on does not change it at all. If the car is off and I put the hazards on, the passenger taillight does sequence properly but it's dim. The back up lights work fine.

I'm stumped. I'm beginning to think the taillight harness or lamp pigtails I bought are wired wrong? Any other ideas?

Thanks!!!

Somebody has to have seen this before...

I think one of the main symptoms of my lighting problem here is that the brake light on the passenger side, while dim, lights only when the car is off and the brake pedal is pushed down. Then when the car is running, it doesn't work at all... Has someone seen that before? Is there a likely faulty part or incorrect wiring that could cause that? Thanks!!!

Thanks, I should mention that I've already replaced the LED unit on the passenger side of the car, with no change. [Edit: I'll see also if they have seen this before.]

I agree it's almost unbelievable that the brake light works dimly when the car's off, and not at all when running. I figured that would be a tell-tale sign of something for somebody.

I'm going to buy a new taillight harness to replace the other new one that I put in about a year ago. I can't gaurantee the lights ever worked properly after installing the new harness back then (since the car was at the paint shop for some time). I've had a number of defective brand-new electrical repro items the past couple years so perhaps that's it again...