I need to instal a brake controler on my 03 3500, is their a connection under the dash a person can tap into for the blue wire that runs to the rear plug in on the pickup?

 

When you buy the controller, buy the harness adapter for your truck. The truck side plug is hiding up by the parking brake cable.

 

If the truck was equipped with a tow package, there was a plastic bag that had a blue plug with some wires coming out. You can use that to make your own harness when you buy a controller. The instructions are in the bag. It might save you a few bux.

That plug matches the plug under the dash. On my '01 Dakota it was part of the main harness plug. On this truck, it's seperate, and just hanging there behind the parking brake mechanism, to the left of the main harness plug.

 

Be sure to look EVERYWHERE for that harness before you give up. Mine was hidden in one of those small compartments that I had never used. Don't know who put it there, but at least it was in the truck and I didn't have to buy one. It's a simple setup when you have the correct wiring harness. Pretty much plug and play.

 

also check the access holes up against the floorboard/firewall drivers side, look or put your finger in them, that blue wire on mine was folded over and stuffed in.