brakelights taillights

[Robyn5.0]

thanks for your time and help
my problem is that my lights(brake, tail) are bright like they should be ,but only if the car is not running or if it is running only if the car is in nuetral ,when i drive off they all go dim and i get pulled over by the cops : )
1985 ford mustang 5.0 " changed the bulbs already

 

[MustangLX-5.0]

Could be a wiring problem.Loose connections maybe.Is your car an Automatic or Manual? Do the lights get dim if you start moving or do they get dim when you shift into Drive (Auto Trans) ?

 

[Robyn5.0]

they get dim when i start moving ,its a standard

 

[MustangLX-5.0]

Sounds like a bad wiring harness or terminal.A bad ground could be to blame also.Check the wiring behind the fuse panel.Try turning the lights on while the car is off and moving around some wires down there.Also,do the same with the wiring behind the tail lights.Check any ground connections back there also.

 

[DirtyD916]

might be a bad alternator but what do i know

 

[jerry beach]

might be a bad alternator but what do i know

That is a good thought. Do the headlights do the same thing? Or is it just brake and tail lights, no drain on anything else?