Troubleshooting a Tekonsha P3 Brake Controller that Reads Trailer Not Connected

Question

Question:

Hello, I can not get my new Tekonsha P3 brake controller to recognize the trailer connection. I purchased the controller and the 2005 F150 specific wiring harness. It always says trailer not connected. I have visually inspected almost all of the wiring, truck and trailer. The lights all work correctly to include brake lights but no trailer brakes. I have also tried checking the wires coming out of the back of the P3. Black was 12v, red is brake lights, white is ground, but blue does nothing. I know blue is the trailer brakes but I get no signal or output when pressing the brake pedal or sliding the manual override on the controller it just clicks and flashes red no connection. I have made sure the fuse for the trailer brakes is good but still no signal?? I have no idea what to even check next. Please let me know what you think. Thank you!

asked by: Dustin

0

Expert Reply:

If you sever the blue wire leaving the P3 controller part # 90195 leaving enough room to reconnect it and test the end of the wire leaving the controller with a circuit tester like part # PTW2993 you should see voltage when you slide the manual override lever. If not, then the brake controller is bad.

If you see voltage there instead then the problem is somewhere on the brake output circuit of your vehicle or trailer. Corrosion on the trailer connector typically causes this problem. If cleaning the connector on your trailer and on your tow vehicle does not fix the problem you will need to inspect the condition of the brake output circuit on both your trailer and on your tow vehicle looking for any obvious signs or shorts like cut or exposed wire and fix as necessary.

I attached an FAQ on troubleshooting brake controller installs for you to check out as well.

expert reply by: Jameson C

0

Chris T.

4/29/2020

Both. Trailers are new And both plugs on the truck are new. The truck is a 1998.5. Dodge 2500. In one of your install videos. It makes reference. To if the plugs are not a factory. Plug. There might be something else I need to do to make them work but does not say what? The controller. Recognizes the trailers all the lights turn signals and break lights work. But when you ask for a lot of break. It goes to broken ground no breaks. Is there I a difference between. The wire harness that you guys sell For the 1998. And 99.

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Chris R.

4/30/2020

The truck is recognizing the new brake controller so you shouldn't need anything else done (the video was likely talking about taking the truck up to a dealer to have the computer flashed). If I understand correctly I believe you said the same issue is happening on two different trailers? If that's the case then we at least know the problem is somewhere on the truck. Does the problem occur both when pressing on the brake pedal and when using the manual override? If it's just with the brake pedal the brake switch on the truck itself could be going bad, which isn't terribly uncommon on older trucks.

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Chris

4/27/2020

I have the break controller Hooke up with the factory harness that you guys offer. Once the controller gets to 6 volts it shows that there is an open ground . I have by passed that with a separate ground and power lead but still get have the same issue when i apply the breaks. The controller is. Less than a year old could that be bad?

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Chris R.

4/29/2020

A bad controller is possible but unlikely. Since you know the controller's ground is good, I would inspect both the vehicle's and trailer's 7-Way connector. Visually inspect both to check for any corrosion or debris that might be built up around/inside the pins, cleaning out as needed. Let me know if this doesn't help and we can go from there.

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Answer 1

I am not entirely sure what process you took so I'll give you some other things to try, or maybe a different way to test the Prodigy P3 #90195. First, sever the blue wire a couple inches from the back of your controller. Then use a circuit…

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Answer 2

I would start by inspecting the connector on your trailer and the vehicle to make sure there is not corrosion in the connector which could be causing a bad or weak connection. If there is corrosion in the trailer side connector, you would need to…

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Answer 3

The Prodigy P3 trailer brake controller uses a 4-wire hookup. The white wire is to be grounded to the battery negative terminal; the black power wire connects to the battery hot terminal through a circuit breaker; the red wire takes in the brake…

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Answer 4

There are several items you might want to try using for removal of corrosion in your 7-way trailer connector, like part #HM48480. White Vinegar A wedge shaped, slip on pencil eraser or art gum eraser Pipe cleaners PB Blaster If the corrosion is…

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Answer 5

If your Tekonsha P3 Brake Controller, part #90195, displays the error message OUTPUT SHORTED NO BRAKES, the potential causes are a short in the brake output circuit somewhere between the brake controller and the trailer brake assemblies, or a shorted…

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Answer 6

I have a solution for you but you won't be able to get enough power off of the center pin. That's the reverse circuit and it has the least amount of voltage. You won't be able to charge both your break away system and your marine battery…

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Answer 7

You can put a maintenance charge on your trailer battery with the 12 volt accessory circuit of the 7-way. The 1:00 position of your 7-way carries this circuit. You would just need to run a length of 10 gauge wire like part #10-1-1 (sold by the foot),…

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Answer 8

For starters, the fact that you aren't getting output with the brake pedal doesn't indicate a problem. Proportional controllers like the Tekonsha P3 won't output voltage with the brake pedal unless the vehicle is in motion. I'd begin…

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Answer 9

If you are getting a no trailer connected warning on your Tekonsha Prodigy P3 #90195 you may have a corroded or dirty connector which is hampering the connection. Check the vehicle and trailer plug to see if there is any type of corrosion or dirt…

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Answer 10

The overload warning you are seeing indicates that the P3, #90195, detects an excessive current overload condition during operation. This means that there is most likely a short in the brake output wire. The P3 has diagnostic troubleshooting…

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Answer 11

The Tekonsha P3 Brake Controller, item #90195, has built in troubleshooting diagnostics that you can access by pressing the menu button then selecting help and pressing ok. You will then be able to monitor the battery voltage supplied to the unit,…

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Answer 12

The #90195 P3 and the #39510 are both proportional controllers, so if you're testing for brake controller output with the brake pedal is pressed, you're not going to see any voltage with the brake pedal unless the vehicle is in motion. You…

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Troubleshooting a Tekonsha P3 Brake Controller that Reads Trailer Not Connected

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