2001 f350 brake lights but no rear running lights when head lights are on?

Answer 1

first check the fuse for it,then look at the bulbs real good,and if it has a trailer hitch on it look at the wires where they connect to,there may be a short in one of the wires knocking them out,also check the main rear ground wire for the lights,it can be loose and cause this to happen,good luck on finding it.

Answer 2

Sounds like the rear ground wire is lose or has come off. Also the filiment for the running lights in each buld may be burned out. Your rear light bulbs have 2 filiments and the running light filiment in each buld may be blown. If they were working and then suddenly they both stopped working at the same time...then Id say look at yer fuses.

Answer 3

EXCERPT (page 25) from your owners manual:

"Daytime running lamps (DRL) (if equipped)
Turns the headlamps on with a reduced output. To activate:
• the ignition must be in the ON position and
• the headlamp control is in the OFF or Parking lamps position.
Always remember to turn on your headlamps at dusk or during
inclement weather. The Daytime Running Lamp (DRL) system
does not activate with your tail lamps and generally may not provide
adequate lighting during these conditions. Failure to activate your
headlamps under these conditions may result in a collision."