Tekonsha PowerTrac Brake Controller # 39523 Seems to Engage Brakes When Lights are Turned On  

Question:

Expert Reply:

If your Tekonsha PowerTrac Brake Controller # 39523 works properly until you turn on your vehicle headlights then my first suspicion is a problem in the wiring at the 7-way or trailer. It could be that the running light circuit (often carried on a brown wire that leads to the blade contact at the 11:00 position - see linked photo) is somehow being bridged to the brake output circuit wire. The brake circuit is often assigned to a blue wire at the 7-way contact that is in the 5:00 position. A loose strand of wire that bridges these two circuits could explain the odd behavior of your trailer brakes seeming to engage when you turn on the vehicle headlights.

The same issue could occur on the trailer side as well. Carefully inspect the trailer wiring from the 7-way plug all the way to the electric brake assemblies. Look for any signs of cracked or worn insulation on both the running light and brake circuit wires. If both happened to make wire-to-frame contact, then the running light signal could leak into the brake circuit and cause the brakes to engage.

If you have a circuit tester like # PTW2992 you can test the input and output wires at the back of the PowerTrac for proper functionality. Disconnect the trailer to do this. The RED wire carries the brake light switch signal to the controller to tell it to activate. This wire should carry a signal only when you press the brake pedal. If you detect a signal on the red wire when you turn on the vehicle lights (but do not press the brake) then there is a wiring fault in the vehicle that is allowing the light signal to enter the brake circuit. The BLUE wire from the PowerTrac carries the output signal to the 7-way and trailer. This blue wire should carry a signal only when you either press the pedal or push the manual override on the controller. Again, if you detect output from the controller when the lights are on but without pressing the pedal or the override then either the controller is damaged or again there is a wiring fault in the vehicle.

You can also try the truck with a different trailer, and vice-versa, to see if the problem persists with either. That will help you narrow down the source of the problem. If a different truck works fine with the trailer then its likely an issue in the truck; if a different trailer's brakes operate properly then the problem is likely to be in the trailer's wiring.

expert reply by: Adam R

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Julius S.

3/15/2020

I am busy installing a tekosha protrack brake controller Three of the 4 wires are connected just the blue to the trailer is not connected. I do not see any light come on on the controller yet. Is that ok.Will the green led only come one ones the trailer is connected.Thank you for help .

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Chris R.

3/16/2020

The green LED on the PowerTrac will only illuminate when trailer brakes are connected. Since the unit uses the blue brake output wire to detect this connection, you won't see this light until that circuit is completed. This means what you're seeing (or not seeing) is completely normal thus far.

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