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All Trailer Lights Blink When One Turn Signal Is Activated  

Question:

i have put knew male and female plugs on my boat trailer and you put the right or left bliker on with lights they all blike do i need a earth some were

1

Helpful Expert Reply:

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 your trailer, you can check for a secure ground connection at the trailer connector. Make sure the white ground wire is firmly secured to a clean bare-metal surface that is free of paint, rust and grease. Next check that the ground wire for the vehicle's wiring harness also is secured to the vehicle at a clean bare-metal surface that is free of paint, rust and grease.

If your vehicle's trailer wiring harness is a hard-wired type (not a quick-connect pre-wired plug-and-play type) then you need to check that the brake light wire on the harness is grounded.

I have linked an article on troubleshooting that will give you additional information. If you happen to have access to a different tow vehicle and/or trailer, you can try substituting one or both to see if the problem can be isolated to either the vehicle or trailer. If you have a circuit tester like # PTW2993 you can disconnect the trailer and test the pins on your vehicle's connector for correct operation.

expert reply by:
1
Adam R
Karl P. profile picture

Karl P.

5/26/2020

Hello, I have a vermeer trailer the is having lighting bleed back. What I mean is that when the left turn signal is on the lights are bright but the right side blinks very dim. And the same goes for when the right signal is on it is bright and the left blinks dim. I thought is was a grounding issue but this hasn't seem to fix the problem. Any thoughts? Thanks for your help.

ChrisR profile picture
Etrailer Expert

Chris R.

5/29/2020

Most likely there's an exposed section of wiring on one of those circuits that's making contact with the other - either somewhere along the trailer wiring or even inside the connector itself. Inspecting all the wiring can be difficult so I would start at the connector. Look for any debris or corrosion built up inside or around the pins, cleaning out as needed. A lot of times corrosion can bridge a couple of circuits together. Let me know if this doesn't resolve the issue and we'll go from there.
Greg profile picture

Greg

7/28/2020

I'm having a similar issue to the original questioner: The brake and running lights will start flashing when the turn signals/hazards are activated. The trailer lighting works fine with other vehicles so I'm certain the problem is in my truck. I've replaced the trailer harness and this still doesn't rectify the problem. The truck's lights all seem to work fine but perhaps there's a small short somewhere that's dropping voltage to the trailer? Seems like some of the lights have a bit of play and corrosion in the fixtures. I don't know how to check the voltage on the turn signal wires as I have a cheap multimeter and the voltage is constantly changing (with the flashing). All the other wires on the harness (tail, brake) read the same approximate voltage as the battery when using the trailer harness ground, so does this suggest the ground is fine? "If your vehicle's trailer wiring harness is a hard-wired type (not a quick-connect pre-wired plug-and-play type) then you need to check that the brake light wire on the harness is grounded." What do you mean by this? Any feedback would we so greatly appreciated as I've been struggling with this for ages now! Cheers!

JonG profile picture
Etrailer Expert

Jon G.

8/5/2020

Instead of checking for a specific voltage reading what I'd do it just verify that the running light function is getting power with your turn signal on by testing the pins on your truck with your multimeter instead of the trailer. If you are seeing some play and corrosion with your light fixtures then that can definitely be contributing to the whole problem. I'm not sure what specific wiring harness Adam is talking about but he is essentially saying that you want to make sure any grounds you have connected to these wiring circuits need to be secured and connected to a clean, bare-metal surface.
Bruce profile picture

Bruce

4/27/2022

I had the same thing happen after putting a new plug on the trailer. Simply wired wrong. Had one turn signal wire and taillight wire crossed. Changed them and worked fine.
DavidB profile picture

David B.

4/28/2022

Hey Bruce, thanks for the input! I'm glad you were able to troubleshoot the issue and get a fix for it!
Hélène profile picture

Hélène

6/25/2024

TY for your info above. Where do I find the trouble shooting info? We we have a 1999 E350 supper duty van pulling a 2007 Sydney Outback by Keystone. We wired up the extra strip of lights to the back of the camper. Connected to a separate plug than the one that runs lights and breaks. Both work beautifully doing the half strip blinking for turning as well as the smaller trailer lights until you turn the head lights on. The new blinking light now pulses very dim. ?

BudM profile picture
Etrailer Expert

Bud M.

6/25/2024

@Hélène The link to the troubleshooting article is near the bottom of this page. You can also get to it and other help articles by clicking the CUSTOMER SERVICE link at the top of the page and then clicking HELP ARTICLES found under ALL HELP INFORMATION. Based on what you are saying it does sound like a ground issues and not having a strong enough connection for all the power going to the trailer lights.
Adam R. profile picture

Adam R.

9/12/2024

I may have a similar situation, I have a 1995 Wildwood trailer, an am having issues with after I turn right turn signal on, all clearance an tail lights begin flashing. I cleaned both ground connections to bare metal on trailer and truck. I have had trailer now for 4 yrs, with out any problems. Appreciate any suggestions, thank you

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