2003 durango 4x4 4.7 sxt....brake lights stuck on when lights are turned on.i replaced rear wireing harness because old one melted.was told theres a switch under the brake peddle or maybe a spring broke was just wanting to confirm this....

 

Yes there will be a switch under the brake pedal. Mine went out and left brake lights on full time. Common problem. I also had to adjust the bracket on mine a little bit to make them function properly

 

i got one from advance and it didnt work so im waiting on another one to get here but if thats not the prob is there anything else it could be.

 

I would like to help more but I'm afraid ours are too different. Mine is a 98, and yours has a mostly different harness and completely different interior than mine. So my service manual wouldn't even help you with your issue. Just make sure your brake switch is working properly before diagnosing or buying more parts. My brake pedal arm wasn't pushing the switch far enough so I had to adjust the bracket so that the switch would be pressed in further (about 1/16th of an inch more). I don't understand why it's only doing it while the lights are on.... those circuits shouldn't be crossed anywhere. Very odd set of circumstances.

 

If you pull the connector for that brake switch, for diagnosing your problem, it's the same as having a working switch. The switch closes the connection to light the brake lights when the pedal is pressed. Pulling the plug insures it's an open circuit, no lights. I seriously doubt your problem is at the brake pedal.

 

True. Just unplug your brake switch, turn your lights on and see if you still have your issue. If you do, it's somewhere else. If your issue goes away.... still odd that it's related to running lights. But would just be good to rule out something easy.