Trailer Connector Wiring Problem/Question

[mrtrombley]

When I hooked up to tow my trlr last month, my new MaxBrake gave the message "check trailer wiring" and I had no brakes on the trlr. At first I thought I had a problem with the MaxBrake, but all other wiring/lights seemed to be ok. So controller seems to be ok. Although when disconnected from the trlr, I still get the same message all the time.



I disconnected the wiring harness from the MaxBrake and put 12 volts to the trlr brake wire. I then went to the trlr bumper plug and measured the voltage between the ground connector and the brake connector and only read 4. 3 volts! I also checked the in-bed plug and got the same results. I also measured across the 12v charging connector to ground and got the full 12 volts.



Any reason I would have a voltage drop like that? Bad ground? A partial short somewhere in the line? Anyone had a similar problem?



I figure I could run a new wire from front to in-bed plug, then to bumper plug. But I want to make sure I am not missing something as I know wiring can run into some crazy snags. Thanks for any help.

 

[Joseph Donnelly]

First, check the wiring harness for the truck. Make sure the blue wire that goes from the connector for the brake controller to the 7-blade connector at the rear bumper is good, low resistance, and reading 12 volts at the bumper when you apply 12 volts at the under-dash connector. If it is OK, see if you get full voltage through the brake controller when it is set at "maximum" braking effort. You may have a defective brake controller, or a bad connection somewhere.

 

[mrtrombley]

Thanks Joe, I believe it is in the wiring someplace. When I applied 12 volts at the front (after unconnecting the controller) I only got 4. 3 volts at the bumper plug. I was wondering if there was something in the line that I should know about. I see some on here talking about a TIPM. I don't think I have that, do I? With the controller connected, applying the brake did not give any additional volts at the rear.

 

[Prairie Dog]

You should get the full 12v through the wire with what your doing. I would suspect somebody probed the wires under the truck with a sharp probe allowing water and corrosion to set in.

 

[seafish]

Thanks Joe, I believe it is in the wiring someplace. When I applied 12 volts at the front (after unconnecting the controller) I only got 4. 3 volts at the bumper plug. I was wondering if there was something in the line that I should know about. I see some on here talking about a TIPM. I don't think I have that, do I? With the controller connected, applying the brake did not give any additional volts at the rear.

The 2011 in your sig DOES have a tipm.



The 2004. 5 does NOT have a tipm.

 

[HBarlow]

Dick,

As others have suggested, it sounds like you have a damaged wire between brake controller output under dash and the seven pin connector at the rear bumper. There should be nothing in the circuit other than a straight run of wire.

The TIPM didn't show up until the '06 model Ram trucks.

I would look at the junction between OEM truck harness to the seven pin female at the rear and the in-bed seven pin female for fifthwheel.

Sometimes when a harness is added the wiring can be damaged or open to moisture and corrosion. The best way to supply the in-bed connection is with a plug and play harness that simply plugs in under the rear bumper.

 

[mrtrombley]

Thanks for the advice guys, I hope to look at things again this weekend.

 

[Hoefler]

If you have one of those plug relocation kits that plug into the back of the trailer plug on the bumper then the harness plugs into it, disconnect it and plug the harness back into the factory trailer plug in the bumper. Plug the trailer into the bumper, do you have the same problem?? I had one of the relocation harnesses go bad on me and caused a trailer brake error code on the controller. Replaced the harness and all is good.