I have 2003 Dodge Ram 2500 2wd with 5.9 Diesel. Recently (last 3-4 months), when I hit a large bump, the headlights, parking lights, and dash lights turn off. When I tap the brake pedal, they turn back on. I am very confused. The first several times this happened, I was towing a 24' trailer, so I thought maybe trailer wiring had a short. It just did it again the other day with no trailer attached. I have an aftermarket keyless entry system and brake controller installed, but have not had any issues like this until recently and both those devices have been on the truck since it was new. Does anyone have any ideas? I believe the headlights are powered by the front control module (not sure if the parking lights are too.) I did have to replace the FCM about 6 years ago when one of the headlight driver circuits failed, but haven't had any problems with the FCM since. Thanks for any input.

 

Welcome to the site. You already know you either have a lose power wire/ground wire or shorted wire that is shorting out temp. when it hits hard and connects with something and to be honest, my first thought is PDC/FCM

 

weedahoe,
Thanks for the response, thats the path I was headed down. I actually, figured out exactly what is going on yesterday...turns out the switch that engages my "turbo timer" function of my remote start module has an intermittent short and needs replacing. When I hit a boig enough bump, it would short and it thought I had pressed the button. I just kind of stumbled on the solution. The good news is I found my solution, too bad it is isn't likely to help anyone else out there as it is something tied to my aftermarket truck configuration. Anyway, thank for the help.

 

Glad you tracked it down and figured it out