Turn Signals on Trailer Not Working When Running Lights are On

Question

Question:

Hello. I have a very similar issue to what was described by a previous individual brake lights, running lights and turn signals on both trailer lights work but when the running lights are on, neither turn signal on the trailer lights, will work. What I will include for information which was not included in the other individuals issues is that both hazard lights will work on the trailer while the running lights are on, so I dont understand why each individual turn signal will not work while the running lights are on. ???? I have taken apart the 4 blade trailer adapter, including testing each contact for continuity and each one is fine. Please help if you can with this as this is very frustrating. It is a 4 wire system: Ground white, Yellow, Green and Brown wires. Thank you for your help.

asked by: James B

0

Expert Reply:

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 lights to pass, but not enough for everything. With the running lights on, there may simply not be enough power to also activate the turn signal lights. Considering that all of the trailer rear light functions appear to work fine individually, this is very likely the issue.

I recommend checking to make sure your trailer connector's ground is secured to a clean bare metal surface on the trailer frame. Make sure that there is no debris or corrosion that may be preventing the required clean connection. You can also check to see that each individual light's ground is secure.

If all the ground connections look good, you should also make sure the current rating of your vehicle wiring harness is sufficient to handle the trailer lights.

Please let me know if you are still unable to find the cause of this issue and I will be happy to look into this further.

expert reply by: Chris R

0

Thamus J.

2/22/2024

Running light on passenger side blinker not working only blinker but blinker doesn’t work on that side if running light are powered

Chris R.

2/26/2024

@ThamusJ Wiring is fun isn't it? While I can't be certain what's going on in your case, it does sound like a classic weak ground scenario since the problem seems to only come up when you have the running lights on, which requires the most amperage to run. When you have those on, there isn't enough left over to also kick over to the signal lights, which makes me think that you might just need to re-do the ground attachment on that white wire. Let me know if that doesn't help.

Ron E.

3/19/2024

@ChrisR I have the same issue as described above, but it's only my left side blinker having the issue. Each blinker has its own ground. I just replaced the entire light, wires to it and ground connection to bare clean metal and still no luck.

Jon G.

3/29/2024

@RonE I would try running power directly to that light to make sure the assembly is working properly. If it is then you might need to replace the wiring from your trailer connector all the way back to the assembly. This will require 16 Gauge Wire # 16-1-1 and Butt Connectors # DW05744-5.

See All (5) Replies to Thamus J. ∨

Colin

6/28/2024

I have similar problems. Runnings lights all work. Signals/ hazards work. But won’t work together. I have redone ALL grounds to bare shiny metal with brand new connectors, re did main 7 pin ground to frame. I put extra ground wires from each tail light to trailer frame. I still have the same problem. All fuses in truck are working properly. I’ve tested ohms readings with multi meter everything is testing as it should, as well as in dc volts.. I’m running out of ideas and patients. Please help

Ray

7/23/2024

Hi Chris Currently my trailer has no running lights. When 4 ways turn on , all the lights come one, when brake is pushed, only one tail light comes on. When I signal left no lights come on. When I signal right all lights come on. Any suggestions where to start looking Thanks

Chris R.

7/24/2024

@Ray That sounds fun! It seems like basically nothing is quite working like it should. I'd start by testing the 4-Way on the vehicle side for function, using a circuit tester at each pin while activating the corresponding function in the vehicle. If everything is getting power like it should there, you know the problem is somewhere on the trailer. If that's the case it sounds like there's likely a short or exposed portion of wiring somewhere that's causing power to bleed into other circuits.

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

Hey John, the difference between those two part numbers is the grease cap that comes with the hub. The part #AKHD-655-35-EZ-k has a grease cap that has a removable center plug for easier access to a grease fitting like what you have whereas the part…

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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

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 5

You can use leaf springs that are rated higher than the axle without any issues as long as they measure the correct measurement for your trailer. For example the 6-leaf double eye spring for 7,000 lb axles part #e64SR measures 24-7/8" eye to…

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Answer 6

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 7

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 8

On a trailer the brake lights and turn signals operate on the same wire/bulb. So, it is odd when the turn signals work, but the brake lights don't. There are 3 possible causes for this that are more likely than any of the other possible causes.…

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Answer 9

On my 2004 Dodge Ram (which would be the same as your 2003) the factory trailer connector plug split off from a larger wiring harness on the inboard side of the drivers side frame rail near the rear bumper. There should be a rectangular connector…

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Answer 10

I am sorry, but I am not showing that part Multi-Plug T-One Connector, part #20135, is a fit for your 2003 Dodge Ram 1500. You need the 7-Way and 4-Way Replacement Connector for Dodge Trucks, part #42145, for your truck. It will plug directly into a…

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Answer 11

The seal for your Dexter 4,400 lb axle is part #58846 which we also have in a pack of 2 listed as part #RG06-050 these have an inner diameter of 1.719" and an outer diameter of 2.565".

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Answer 12

Hello Chris, thanks for reaching out. Based on my research, it looks like the AL-KO-7230 is a hub for a 3,500 lb axle with a 6 on 5-1/2" bolt pattern. We do offer a replacement for this, and for that I recommend the following: - Trailer Hub and…

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Turn Signals on Trailer Not Working When Running Lights are On

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