tall007dfw

So weird thing here.. Car is a 2001 Gsr hatchback. The brake light works when the running lights aren't turned on, but the light is just slightly dimmer on the driver side. Now when i turn on the running lights tail lights work, but when i hit the brakes not only does the brake light not turn on but the tail lights turn off as well. I've volt dropped the socket and am getting 12 volts to both pins on the socket.. I'm out of ideas and people to ask. PLEASE HELP ME.. Thank you in advance.

wunfstgsr

I believe they are dual filament bulbs so it could still be bad try replacing the tail light bulbs. If no one hacked into any of the wires coming off the harness for the tail lights look into new bulbs and check all the fuses for tail lights and running lights under the dash.

tall007dfw

Bulbs were the first thing I tried, fuses were the second. That's why I'm so confused.

avisitor

Dual filament bulb ... If it is what I think is the problem, then ... Bad grounds

Brake lights work when tail light off:
When tail lights are off, that one side is held low.
Brake lights turn on. It uses the other filament as a ground (held low)

Tail lights work when brakes lights off:
When the tail lights are turned on, that side is held high
And brake filament is off (held low). Allowing for a ground path.

No lights at all when both tail lights and brake lights are on:
So, when applying brakes, you have both sides at 12 volts
No current flow. There is no ground.
Which means no brake lights and no running lights.

The fix:
It is corrosion of the ground that is preventing proper operation of the bulbs.
Try cleaning all the grounds. The one in the sockets and especially the big common one for the lights.
It is the one going from the bulb sockets to the chassis.