All four of my brake lights light up on the parking light setting when i have the headlights on, but the inside light on the driver’s side assembly doesn’t light up when i press the brake - it just stays on, but dim for the parking light mode.
It doesn’t bother me, I still have all the other brake lights working, but I just got pulled by a state trooper, and he said I needed to fix it. Trying to avoid a ticket…
I looked at the back of the assembly, and it’s all stock and all appears well - no tampering at all.
Pull all the brake/tail light bulbs, [except high mount brake], install them one at a time checking to see if park and brake lights work properly each time you install a bulb.
What can happen with older bulbs is the filaments can touch each other in the bulb so if you turn on the park lights the brake lights also turn on.
We get 2-3 cars a year with that problem, anytime a car that has dual filament bulbs comes in with a problem like yours it is the first thing we check, it may not be the problem but it needs to be eliminated as the problem.
Other things to check for are proper grounds for the tail lights, make sure the trailer lights connector did not get pinched off or damaged in any way. 94