Troubleshooting Brake Controller Showing Not Connected When Trailer Is Connected

Updated 07/17/2015 | Published 07/16/2015

Question:

I have a 2007 Dodge Grand Caravan SE with 3.3l v6 that I am using to pull a Rockwood popup trailer. The trailer is new to me and although fitted with electric brakes they were not operational at the time of purchase damaged magnets and aged wiring. I have replaced both brake assemblies with Dexter 7 x 1 1/4 and have replaced all blue brake control wire with the exception of the 6 pin block connector and pigtails on the trailer along with the main ground and individual grounds for the right and left brakes. All new wiring tests out well for continuity. The vehicle has a Primus IQ brake controller that was professionally installed. When connecting the 7 pin trailer end into the vehicle all lights work properly but the brake controller reads NC, not connected. I have also replaced the vehicle end connector, trailer end connector and 7 wire cord from vehicle to trailer. If I jumpfoot the blue brake control line and ground line from the vehicle end connector to the trailer the brake controller acknowledges the trailer and the brakes work although weakly - I havent adjusted the brakes yet trying to resolve operational issue. I have now replaced the trailer side 7 pin connector with 3 different connectors presently a Hopkins. I just now noted in one of your help sections that the voltage on the brake line should read at or near 12 volts with the manual boost at full. I am getting only 5 volts 1.5 v with no boost and brakes full depressed. Technical support for the brake controller is telling me this may be acceptable......other factors lack of deceleration etc. may influence actual output of the controller. I note that I measure good continuity on both the brake and ground lines from the 7 pin trailer end of the cable connecting the vehicle to the trailer to the 6 pin block connector end. But in applying my test light from the blue wire to ground, when plugged into the vehicle, I cannot wake upfoot the controller. This leads me to think I have a 7 pin connector compatibility issue, but multiple replacements on the trailer side have not helped. I cannot seem to isolate whether I have a brake controller issue or a 7 pin connector compatibility issue. Thank you in advance for your assistance,

asked by: John H

Expert Reply:

Since you did not say what the age of the brake controller is the first thing I recommend is to connect the trailer.

Go to the rear of the vehicle and make sure the vehicle side connector is receiving 12 volts. If it is not then sever the blue wire at the back of the controller about 4 to 5 inches from the controller. Use a voltmeter and test the blue wire coming from the back of the brake controller. Slide the manual gain all the way. It should read about 12 volts. If it does not there is a problem with the brake controller and it will need to be replaced.

If it checks out okay, move to the wire coming from the pin for the brakes on the trailer side and check for the same voltage. If that connector and wire checks out, there is a problem between the connector and the brakes themselves. Check for corrosion, damages or loose wires and repair as needed. Make sure all of the brake magnet grounds are run to the main trailer ground.

expert reply by: Jeffrey L