Trailer Turn Signals Both Blink when Just Left Turn Signal is Activated

Question

Question:

all the trailer lights work fine until i hit the left blinker then the back two trailer lights start to blink as if i turned the hazards on

asked by: Hayden

0

Expert Reply:

What you are describing is normally the result one 1 of 3 issues: First, there could be some corrosion in or on the connectors on the vehicle or trailer side or both. Second there could be a bad ground. Bad grounds can cause all sorts of bizarre things to happen as electricity likes to take the path of least resistance. And third, sometimes wiring mistakes can be made if the trailer connector is a wishbone type harness (4-Way flat but with 5 wires coming out, 2 for running lights).

First disconnect the trailer and use a circuit tester, like # PTW2993 if you do not already have one, to test the vehicle side connector for the proper functions. I have included a link to a video that explains how to test a converter along with an FAQ article on troubleshooting 4 and 5-Way wiring.

On the trailer side you will want to make sure the connector is clean and that the main ground is connected to a clean and corrosion free bare metal surface. You will also need to do the same for each of the trailer lights. Also if the trailer has an aluminum frame, tilt bed, or folding tongue then it will help to run jumper grounds from the lights to the main trailer connector ground.

expert reply by: Michael H

0

Dan T.

5/10/2020

I have the magnet type lights for my car trailer i have the 4wire plug everthings is working good until i turn on my turn signal both lights blink i have move the ground3 times on my truck with the same result i could use some help.

Reply

Chris R.

5/13/2020

I would start by testing the 4-Way connector on your tow vehicle. Use a circuit tester on the turn/stop circuits while they're activated on the vehicle - see if you get power on both turn/stop circuit pins with just one side activated. If so, this means the issue is somewhere on the vehicle side. In this case you will want to visually inspect the 4-Way for any corrosion/debris built up inside the pins, cleaning out as needed, and check the wiring right behind it for any exposed or pinched sections that need to be repaired/replaced. Let me know what you find and we'll go from there.

Reply

Kevin

3/25/2024

@ChrisR I have the same issue. I ran all new wiring and lights. I even bought a new adapter from the 7 to the 4. I do know when I turn the right one on it works but lacks power to feed the side bulb

Reply

Answer 1

If both turn signals blinking at the same time is a new problem that has occurred after the harness had worked fine before, there are a couple of possibilities that may be causing the issue. First, the easiest thing to check are the trailer…

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Answer 2

The most likely cause for the incorrect behavior of your trailer lights, where activating one turn signal causes all trailer lights to blink, is an insufficient ground (or a short to ground) on either the vehicle or the trailer. Since you re-wired…

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Answer 3

I consulted an online copy of the 2013 Jeep Wrangler Unlimited Owner's Manual, and found that the information regarding flat towing procedures begins on page number 532. The procedures outlined make no mention of what position the key needs…

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Answer 4

What you are experiencing is one of the classic symptoms of an insufficient ground connection. Check that the ground connection for the trailer connector on the truck is securely grounded to clean metal. If the connection point is corroded,…

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Answer 5

The Demco SBS Stay-IN-Play DUO Supplemental Braking System - Proportional #SM99251 is going to be connected to your vehicle's battery to be powered which will drain your vehicle's battery. To keep the battery charged while towing you…

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Answer 6

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 7

Technically Hopkins wiring harness #HM56200 is a 4-diode system but it uses a converter box instead of separate diodes. So if you are looking at supplemental braking systems you are going to need to use the brake light relay #RM-88400 to prevent…

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Answer 8

Lance does have a proprietary plug, but many customers see a standard 6-way or 7-way round and notice it doesn't fit their factory 7-way as well. I've attached an article to help if you have one of the 7-way or 6-way round connectors…

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Answer 9

You will have no problem installing a B&W Turnoverball gooseneck hitch in your 1997 Ford F-350 with the Duraliner bedliner. You will have to cut through the bedliner for the hitch ball hole and for the safety chain loops. Also, if the bed…

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Answer 10

Yes, the heat shield on your 2017 Chevrolet Silverado 3500 while installing the B&W Turnoverball Underbed Gooseneck Trailer Hitch w/ Custom Installation Kit part #BWGNRK1016 will need to be removed and then discarded. The heat shield is not…

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Answer 11

Your brake lights and turn signals for each side are on one circuit. The left side turn signal and brake light is generally the yellow wire going into your trailer connector. The first thing to do is check the fuses on your tow vehicle. Next,…

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Answer 12

Yes, if you were to use anything other than a magnetic light kit on your 2017 Jeep Wrangler Unlimited you will need to use the brake light relay #RM-88400. The relay is meant to prevent the Jeep's brake signal for overriding the turn signal…

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Trailer Turn Signals Both Blink when Just Left Turn Signal is Activated

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