Troubleshooting Brake Controller Install that Does Not Show Voltage on Circuit Tester

Updated 03/04/2019 | Published 03/02/2019

Products Featured in This Question

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(73)

$72.59

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires

(3340)

$135.47

Hook Probe Circuit Tester

(60)

$12.49

Question:

I just recently purchased this product for my Ram Promaster along with hitch76050 and ETBC7I think so I could tow a camper trailer with brakes. After following along step by step and making sure I have a good ground into the frame, I only have 12V power working as shown on my Curt 7pin tester. And also, I hooked up the van to another trailer and this trailer only has trailer brakes working as the brake controller works, no lights at all. Where could the problem lay? Do you have any experience with this? Thanks.

asked by: Zach

Expert Reply:

Brake controllers don't always work with 7-way circuit testers like you mentioned. The brake controller needs to see the amperage draw of brake magnets to know that a trailer is connected and a 7-way circuit tester won't provide that. This prevents the controller from registering like what you mentioned. Since the controller worked when you hooked it up to a trailer that means it should be fine. Now the trailer lights are most likely related to the 4-way trailer wiring of the harness vehicle before the # ETBC7 was installed. I'd verify first that it's working okay and then make sure the 7-way adapter is connected properly. You'll want a circuit tester like part # PTW2993 for this if you do not have one.

If the voltage checks out there but the trailer lights still don't function right then the problem is on the trailer wiring. That would mean that problem is either due to a ground issue or a short issue.

Make sure that the trailer side connector are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces. The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

If the problem is on the vehicle side then I would first recommend you double check how the harness is installed on your vehicle, make sure all of the connections are good and tight. You should check all towing related fuses and relays as well.

expert reply by: Jameson C