Troubleshooting Open Ground Error On Tekonsha Prodigy P3 Brake Controller

Updated 08/04/2017 | Published 08/03/2017

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Hook Probe Circuit Tester

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Dielectric Grease for Electrical Connectors, 2 oz.

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Question:

i have a teconsha p3 controller. towing an enclosed 16foot tandem axle cargo trailer with 2 different vehicle. recently, started getting open ground - no brakes message when braking, with either tow vehicle. seemed to happen when brake voltage reached 6v, then 4v, then 3v. now, no trailer brakes. checked grounds and wiring in both tow vehicles. all good. any suggestions on checking out the trailer? 3 years and 15,000 miles on new trailer.

asked by: Steve

Expert Reply:

It sounds like the bad ground is on the trailer side. Check your ground connection to the frame of your trailer and make sure it is free of rust, debris, and corrosion. It should be a solid bare metal to metal connection.

Another thing to check is your trailer connectors on both the vehicle and trailer side. Make sure you have clean connections with no bent pins. I recommend using a some dielectric grease # 11755 to keep moisture out and help with the electrical connections. You can use a circuit tester like # PTW2993 to check your brake controller signal at the pin (5 o'clock position) when the trailer is unplugged and you are facing the rear of your vehicle. Use the manual override on your controller and the light should start dim and get brighter as you increase the slide/brake power. Then connect your trailer and do the same thing at the power near your brake magnets.

expert reply by: Jason S