Troubleshooting Trailer Brake Controller Installation on 1992 Dodge Ram Pickup  

Question:

Helpful Expert Reply:

It will be easier to find the issue with your trailer wiring by testing the truck and the trailer separately when they are disconnected.

I suggest testing the trailer first. You will need a well charged 12V battery, either the one in the truck or a spare if you have one. A set of jumper cables like # HMBC0860 and two short lengths of wire such as # 10-1-1 will help too. Connect one set of jumper cable clamps to the charged battery and the other to the two lengths of wire. Now apply the negative ground wire to the RV plug's ground contact and the positive wire to the brake circuit contact. The linked photo shows the two pins to use for standard 7-way RV wiring.

With this direct 12V power going to your trailer's brake circuit you should be able to hear the brakes energize and feel their drag if you try to rotate a tire. If you find this brake circuit activates properly then while you're at it you can then test the lighting circuits on the trailer in the same way to make sure the brake/turn and tail lights all function.

If your brakes do not energize with this direct 12V power input you will need to check the wiring from the 7-way plug all the way to each individual brake assembly. Make sure the main trailer ground wire is solidly connected to a clean bare metal spot on the trailer and that each brake's individual ground wire is also secured to a clean bare metal spot on the trailer frame or at your junction box if you have one on the trailer.

On the truck side you will want to use a circuit tester like # PTW2992 to test each contact on the 7-way socket. I linked a picture to show you which function is carried on each pin. it will be easiest if a helper activates the function while you apply the tester to the appropriate pin. To test your brake circuit you will want your helper to press the manual override lever with the controller set to maximum power and maximum boost.

If you do not have a brake power signal on the 7-way you will want to test at the controller. First test the RED input signal wire to the controller. This should connect to the COLD side of the brake light switch above the pedal which is the wire that carries voltage ONLY when the pedal is pressed. If you have the correct brake switch input signal reach the controller's RED wire then test for output on the BLUE wire at the back of the controller. If you have output on the blue wire when the manual override is pressed but you do not have this brake signal on the 7-way then you will need to trace the output circuit until you find the fault, or you can simply run a new output wire # 10-1-1 from the controller to the 7-way.

For reference I linked an article on brake controller installation.

expert reply by: Adam R

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