Troubleshooting P3 Brake Controller Not Working with Travel Trailer Brakes

Updated 02/24/2025 | Published 02/08/2025

Question:

Ive been trying to trouble shoot a brake issue on our travel trailer and decided to test the tow vehicle plug off the 2008 Toyota Tacoma with a Tekonsha Prodigy P3. Following the instructions on the Curt C73NR, these were the results. -RT purple flashing, no clear flash -Bu purple and yellow on -BK no lights. Same with pedal and manual switch on the prodigy. -12v on unless otherwise noted -LT purple flash, no red flash -TM no light I noticed on our last trip out the brakes on the trailer didnt feel like they were working mid trip, but if I recall correctly, all the lights on the trailer worked correctly. Thanks for your help.

asked by: David

Expert Reply:

Hey David, did you check the pins of the 7-way for any dirt or corrosion. That's typically what is to blame for these types of issues and just sanding the pins clean takes care of the problem. The p3 part # 90195 has a pretty good diagnostic feature on it as well though. What does the display say when connected to the tester # C73NR as well as to a trailer?

expert reply by: Jameson C

David

2/20/2025

Thanks for the information, I didn't know the P3 had a troubleshoot function. Yes, the pins have been cleaned. Results from the P3 trouble shoot with the trailer hooked up. Stoplight 14v for brake pedal and lever. Output voltage brake pedal 1.1-2.0v, lever 7.8v. Output current 0.5a brake pedal, lever 2.8a.

Jameson C.

2/20/2025

@David So the P3 with just the brake pedal and no movement detected will be lower voltage like what you described since it uses an inertia sensor to determine how much brake power to apply and when parked it wouldn't sense anything. When you were experiencing low braking performance last time you towed did you try increasing the gain or anything?

David

2/21/2025

@JamesonC I don't recall trying to increase the gain because the error was that there was no trailer attached (red flashing screen). This developed several hours into a trip. I cleaned the connections best I could and limped our way home. There was no obvious change in how the cable felt when plugged in, but the trailer to truck connection seemed like the most reasonable place to start troubleshooting.

Jameson C.

2/24/2025

@David If that's the error code then yes it's the output connection between the controller and the brake assemblies. That can be the blue wire connection at the back of the controller, to the back of the trailer connectors, the pins of the connectors, or possible damage to the circuit before it gets to the brake assemblies.