Troubleshooting Trailer Running Lights Staying On when Vehicle is Turned Off

Question

Question:

my trailer parking lights stay on when the vehicle switch is off

asked by: david p

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Expert Reply:

It sounds as though there is a short or something is mis-wired. Using a circuit tester, like the # PTW2993, check the connection points in the vehicle side connector, to see if there is constant power on the running light circuit (brown wire on the 4-Way) when the vehicle and lights are turned off.

There should be no signal when the lights are off, and a signal when they are on. If there is a signal with the lights off, then there is a problem on the vehicle side. Check to make sure that the brown wire is properly connected to the running light wire at the rear of the vehicle and that the white ground wire is attached to a bare metal surface that is free of dirt and corrosion. It could also be a bad converter.

To test a converter, you will need to first test the wiring going in for function. If the functions are incorrect going in, then something is mis-wired and you will need to start again as if installing the unit for the first time. I have included a link to the installation details for the # C59496 below for reference. Depending on the vehicle, you may need to pay special attention to the directions regarding 2 wire and 3 wire systems and install according to the wiring on your vehicle.

If the functions are correct going in to the converter but incorrect going out, then there is a problem inside the converter and it will need to be replaced. If the signals are correct going in and coming out, the issue lies elsewhere. I have included a video below, on testing a converter, that should help.

If there is no signal with the lights off, then the issue is on the trailer side. If your trailer has a separate battery, make sure it is not connected to the tail light wiring. Also check to make sure all of the grounds are secure and attached to bare metal surfaces free of dirt and corrosion.

You should also check all of the ground connection points on the trailer to be sure the power is not back feeding through the ground when the vehicle is turned off and the trailer is connected. The power from the 12 volt connection could be looking for a ground and is finding the connection through the taillights. Check the taillight connections to the trailer and the ground at the trailer coupler to be sure they are connected to good clean trailer frame grounds.

expert reply by: Michael H

0

Answer 1

I suspect your problem is caused by a damaged or corroded trailer connector. Take a look at your trailer connectors, both the socket on your truck as well as the plug on the trailer. Look for green or white corrosion on the pins or sockets of the…

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Answer 2

This sounds like the problem could be a short or possibly ground related but based on what you have said a ground is much less likely. Look for any pinched or frayed wires on the trailer and fix as needed. This could cause a short resulting in…

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Answer 3

The pump should come on when you hit the brakes with your Dexter EOH system. I hope you have the Dexter #K71-651 for disc brakes versus the #K71-650 you asked from which will not work with disc brakes because it won't provide enough pressure. If…

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Answer 4

I spoke with my contact at Tekonsha, who is doubtful the controller is the issue. The voltage from the controlleer that's sent to the actuator is very minimal, it's just telling the actuator when and how hard to fire. The actuator is actually…

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Answer 5

It sounds like the power from the trailer battery is somehow reaching the right brake and turn signal circuit. The brake and turn signal circuit on the trailer should not be connected to the trailer battery. The first step I would take is to check…

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Answer 6

The suspension in general on your trailer looks very worn. I would replace as much as I could on it to get it back to good working order. The problem with the equalizer cocked to one side like that can happen sometimes. It usually fixes itself when a…

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Answer 7

If your trailer has torsion axles, no worries but it it's a leaf spring suspension you really should have equalizers. Without the equalizer, the trailer will have a rougher ride and the weight won't be balanced across both axles when going…

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Answer 8

Generally you see this situation on a vehicle that has LED lights because there is a power bleed coming from a different circuit into the lighting circuit. LED lights require a lot less power than incandescents, that's one of the biggest benefits…

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Answer 9

You will want the hitch to be set at the height that 1) allows the trailer to be level, and 2) allows you a minimum of 6 inches between the bottom of the trailer loft and the top of the bed rails. The fifth wheel hitches offer several inches of up…

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Answer 10

Choosing the right height setting for your 5th wheel hitch is a combination of a few different variables. First of all you want your towing setup to be as level as possible. With your Montana High Country 340BH level you will want to measure from the…

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Answer 11

It sounds like you're asking about the 12V circuit on the 7-way trailer connector on the rear of your 2003 Chevrolet Trailblazer. Some vehicles will always have power and some others will not. We don't have this specific information for your…

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Answer 12

What you are experiencing is due to the fact that LED taillights only require a very small amount of amperage to illuminate. A tiny amount can cause them to illuminate. Trailer wring for the most part goes totally dead when the vehicle is off. But…

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Troubleshooting Trailer Running Lights Staying On when Vehicle is Turned Off

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