...and it's draining my battery.

Tail lights always stay on. One of the two filaments of each bulb always stays illuminated even if car is completely turned off. Everything else works fine.

Any idea?

Thanks.

 

Brake switch?
I had a car do that several years back. It was the little switch the brake pedal engages/disengages. It was broke and the car thought the brakes were on all the time. Inexpensive and easy to check, I would start there if you have not already.

 

That's what I thought initially, but then both filaments on each bulb would be on--not just one.

Thanks for your input though.

 

I thought the dual filament lights, the brake switch only illuminated the heavier filament.

Easy way to check is to step on the brake pedal.
If the light gets brighter, then it isn't your brake switch.

 

Yeah, I stepped on the brake pedal and the light does get brighter: the heavier filament lights up which is not the one that I have a problem with. So you're right, it can't be the brake switch.

 

might be ur running lights...check the switch on the dash

 

OKCMustangGT, you were right!

I thought it was the running light too, but decided to unplug the brake switch for trouble shooting purposes. And lo and behold, the light went out. So it was a bad break switch. (even if the lights were dim).

Thank you all,

Danny
Chicago, IL

 

I replaced my brake switch 2 weeks ago and now the brake lights won’t cut off.

 

Welcome,

What Year Mustang?

Part Number of Switch Installed?

Either Wrong Switch or Installed Switch Incorrectly.

The Early Switches are a Bit OF Weird.

But Some Further Details Would BE Helpful

Pic of Switch as Installed Would Be Great as Well!

KC