Trouble Shooting Trailer Brakes That Are Weak or Not Working With a Brake Controller

Question:

I have a Prodigy P3 controller with two 12k Al-Ko axles. When manually applying trailer brake, no braking is felt and the current only reaches 6 amps instead of the 15 amps as expected. The magnets were tested using a 12volt battery, the trailer was raised and the front tires locked when the 12v was applied. The rear axle did not lock however you could feel some application of brake. All four magnets each indicated approximately 3.5 amp current draw. The battery was connected directly to the trailer with the same result as when the individual magnets were connected eliminating a wiring issue. At the tow vehicle connector, manually applying brake with no load indicated 12.5 volts, however, when the trailer was connected, the voltage indicated 6-8 volts when manually applying brake and the current draw on each magnet ped to 1.5 amps. My question, is the voltage caused by the load of the magnets and is that voltage excessive. When the voltage s to 6-8 volts out of the controller, there is no braking at all on any wheel. Thoughts?

asked by: Keith D

Expert Reply:

The Tekonsha Prodigy P3 # 90195 should be pushing 12 volts when on full power or when using the manual override lever. The trailer brakes should be drawing somewhere between 3.2 to 4 amps. From what it sounds like, you are within these parameters, so odds are you are having a ground issue with the trailer. Especially with the front axle locking when power was applied. What I would do is ground each brake separately and double check any other ground wires. You will want to make sure all of them have a solid and clean connection to bare metal, making sure it is not aluminum.

You will also need to make sure all 4 brakes are adjusted properly as well. tighten each one to where hub will not spin freely, and back it off until the brake shoes are just barely touching the walls of the hubs.

If neither of these help get everything up and running properly, let me know and we can try something else.

expert reply by: Lazer S