On my 91.5 W250 Cummins I have a issue. When I apply the brakes the rear brake lights work fine however the parking lights up front will slightly glow as well. Any ideas what might be the problem.
I have cleaned & or replaced grounds, pulled the fuse box to see if are any wires touching, removed the pig tail on the firewall where all the main wiring goes. Replaced the multi switch (turn signal lever housing). All looks good there too. Found nothing wrong under the dash as well. Are there any relays in line from the brake light switch that may cause this problem? I’ve been dealing with this problem for a couple of years & found nothing out.

 

The brake lights are back-feeding into the parking lights circuit. Likely happening at the bulbs, or sockets in back.

 

did you check to make sure the brake light sockets are grounded? i have usually found the ground wires fail where the 2 light socket wires connect behind the tail light.

 

yes. I replaced both sides rear & right front maker lamp socket. I’ll go back over all rear bulb sockets.
thank you for your help. If you come up with anything else that may be the problem please contact me.
Doug

 

i have, but i’ll Go back over them to make sure. I replaced both brake/signal sockets with new ones from NAPA.
If you think of anything else please contact me.
thank you for your help.
doug

 

are you 100% sure you got the new ones wired right? it sounds like some wires may have got mixed up.

 

yesa, I am 100% sure. I was having this issue with the old sockets. Passenger side rear didn’t light up at all so I tested it no power got new sockets put them in the same way with the correct wire going to where it belonged. That issue of no passenger signal a wire was it & taped off. Not sure who done that the only people would have been the installer for the wiring for my hauler.
Thanks for the feedback.
Doug