Trailer Brake Lights Work But Turn Signals Do Not Work

Question

Question:

I went to buy a utility trailer at Tractor Supply and when they hooked to the wiring I had only brake lights and no turn signals. I checked the t connecter with a meter I put the black lead on the white wire and I checked all the leads on the plug for voltage and all of them had voltage. I checked it the plug when I first wired it and it show me the turn signals were operating. What should I think?

asked by: Harry B

0

Expert Reply:

Trailers use a combined wiring system meaning the brake lights and turn signals are on the same circuits. Since the brake lights are working on the trailer, and because you have tested the vehicle wiring and it is working properly, there is most likely a bad ground on the trailer.

To be certain you can try a different trailer if there is one available. You can also retest the vehicle wiring using a circuit tester to confirm that the turn signals do work on the vehicle side trailer connector.

If the vehicle side trailer connector has dirt or corrosion build up then that can cause the problem as well. Cleaning out the pins may be all you need to do. The constant draw of the brake lights is stronger than the intermittent draw of the turn signals so it may overpower any additional resistance such as dirt or corrosion. But the turn signals, having less draw, could be affected by it.

If it is a ground issue start by making sure the vehicle side and trailer side connectors are grounded to clean and corrosion free bare metal surfaces. Do the same for the lights on the trailer. If the trailer has a tilt bed, folding tongue, or aluminum frame, you will need to run jumper wires from the light grounds to the main trailer connector ground.

I have included some links that should help you.

expert reply by: Michael H

0

Answer 1

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 2

Blue Ox has an easy system for determining the weight capacity of your spring bars, whereas other companies may use measurements or printed capacity to assist. With Blue Ox, there is a 5 dimple system: No dimples means it is rated for up to 350 lbs…

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Answer 3

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 4

Any time a trailer has turn signals that work but not the brake lights it can be an interesting situation. This is because the brake lights and turn signals on trailer tail lights are on the same circuit. In this situation it is almost always a bad…

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Answer 5

For sag from towing a trailer the best recommendation I can make is actually a weight distribution system. Suspension enhancement will help level your truck while towing. But the advantage to a weight distribution system is that it levels the vehicle…

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Answer 6

I recommend the Dexter Trailer Idler Hub Assembly for 2,000-lb Axles, #8-258BTUC1 with a 5 on 4-1/2 bolt pattern and wheel size of 13" to 15".

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Answer 7

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…

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Answer 8

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 9

Yes, trailer wiring harness #C56332 does have a fuse in a red holder near the large black converter box. If that fuse is fine, then use the vehicle owner's manual to find any fuses related to tow package wiring on the vehicle to check them. If…

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Answer 10

You have it right so far, the 4-way connector is just as you have stated. Remember that Yellow has a L in it so that is the left side brake/turn signal and green has a R in it so that is the right side brake/turn signal. The colors for wiring a 7-way…

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Answer 11

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 12

Typically 4-way wiring consists of 18 and 16 gauge wires. For a 4-way that has all 16 gauge wire you would want the Wesbar 4-Pole Flat Connector #W787264. The part #HM38138 uses 18 gauge for all wires but the white that uses 16 gauge.

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