Left Turn Signal on Trailer Will Not Blink but All Other Lights Work

Question

Question:

I have an aluminium trailer and all of the lights work except for the left turn signal. What am I doing wrong? I have a four prong flat connector on the truck and the trailer.

asked by: Jeff E

0

Expert Reply:

This sounds like a ground issue. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.

The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

expert reply by: Michael H

0

Answer 1

Hey Brian, yes it does sound like your trailer wiring module has shorted out like you suspected. They are designed to do this if they encounter a short in the trailer wiring so that it protects your vehicle wiring. The only solution is an all new…

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Answer 2

You will first want to check the fuses on your tow vehicle. Some vehicles could have fuses for operating the turn signals and brake lights of a towing package. You will want to check if they are installed and working properly. The next thing is to…

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Answer 3

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, inspect…

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Answer 4

The most likely cause for the turn signals not to work when the running lights are on with your trailer is a bad or weak ground. It's very possible that a weak ground connection can be just strong enough to allow sufficient current for some…

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Answer 5

This sounds like a ground problem on the right side. The turn signal not working makes sense because with the brake lights, there is a constant signal coming through which is enough to make the lights illuminate on both sides like they should. But…

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Answer 6

It really sounds like the ground is not making good enough contact on the left turn signal/tail light and because of that it is able to draw enough amperage to illuminate the blinker function of your bulb. There is a chance the converter box of your…

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Answer 7

Most trailer wiring problems are the result of a bad ground. What I would do is start with the connectors. Maker sure the connectors on both the trailer side and vehicle side are free of dirt and corrosion and that they are properly grounded. Next, I…

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Answer 8

It sounds like your trailer tail lights you are using now ground through the mounting hardware. That would be why there are only 2 wires. One of those two wires is going to be for turn signal/brake lights and the other is going to be for running…

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Answer 9

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 10

First, disconnect the trailer from the tow vehicle so you can check the vehicle side connector. Using a circuit tester like part #PTW2993, test the functions of the connector; specifically check the right turn/brake, to make sure the signal is making…

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Answer 11

It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side…

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Answer 12

I am not sure what vehicle you have, or the particular wiring harness you have installed, but most likely a heavy duty flasher is not necessary for the turn signals to properly illuminate on the trailer. What you are describing sounds like a possible…

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Left Turn Signal on Trailer Will Not Blink but All Other Lights Work

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