Hey guys, i am working on my friends sisters durango. Well here is whats wrong, her controls work for her heat when get controls work, but once she hits a bump her heat stops working and if you hit the dash it comes on and then off again. Also at night, if you have the headlights on, if the heater controls stop working, the backlight doesnt illuminate, but when you get the heater controls working, the lights come back on. here ill make it easier to understand lol

Headlights On --> Heater Controls Work --> Heater Control Head Illuminates
Headlights On --> Heater Controls Inoperable --> Heater control head illuminates when headlights are turned off, but not when headlights are on.

Now i took a test light, and put into the power wires, and drove around, aimed for bumps, but no interruption in power supply. I ordered a heater control head to see if its gonna fix the problem, i figured could be shorting out. If you guys have ideas please let me know. Worse comes to worse ill have to return the part. Thanks guys...

 

It really sounds like a ground wire or a problem with something being loose on the switch itself. I'm not very good with electrical so that's the only thing that comes to mind for me.

 

Looking at the wiring diagram (i can't read them real well) it seems like you get power to the Heater Control from the headlight junction box. So my guess is that when the H/L are on you are loosing the power to the Haeter control.

but then again I could be way off too.