Trailer Lights Blink

DScott · Dec 9, 2008

I have noticed that the lights on both of my trailers blink and go dim when I hit the brakes. Going down the road they will just kind of go dim for a second every once in awhile and when you hit the brakes it's like they are burning at 50% or so. My goose neck trailer has the small round connector in the bed and my small bumper hitch trailer uses the larger round connector under the bumper. They both seem to do the same thing. Brakes flashers and etc work fine.
I don't know much about the hook up except that it used to work fine but I was thinking that it's a ground issue but since both connectors do this it made me wonder. Do these two connectors share a common ground that could be loose or corroded?

bruster · Dec 9, 2008

I've seen the same problem all the years I was a truck road mechanic. Ground

You will have to check under the bed to make sure where both cords are hooked into the system. Make sure that the connected wires are SEALED, not just butt connected and taped. If they are falling apart, re splice the ENTIRE cord end, and reseal with heat shrink tube. You might want to even check the plug ends (inside) and see if your wires are tight in the socket. Frame grounds are even better than harness grounds when powering trailers. Don't poke wires to find power, but if you do , seal immediately. Good luck!

thurlow · Dec 9, 2008

Ground........exactly right; I always assume a trailer wiring problem is ground related, until checking it out proves otherwise. I long ago gave up on grounding thru hitch, to frame......anything except a connection all the way back to the battery. Actually, the purist would say it's not a 'ground' unless there was a rod driven into the soil.

DScott · Dec 9, 2008

(quoted from post at 08:17:14 12/09/08) I have noticed that the lights on both of my trailers blink and go dim when I hit the brakes. Going down the road they will just kind of go dim for a second every once in awhile and when you hit the brakes it's like they are burning at 50% or so. My goose neck trailer has the small round connector in the bed and my small bumper hitch trailer uses the larger round connector under the bumper. They both seem to do the same thing. Brakes flashers and etc work fine.
I don't know much about the hook up except that it used to work fine but I was thinking that it's a ground issue but since both connectors do this it made me wonder. Do these two connectors share a common ground that could be loose or corroded?

OK, Thanks for the reply. I will dive under the truck (when it's drier and warmer than today) and check out the ground. It has a factory harness for the bumper hitch connector and the small in bed connector was added by the place that installed the GN hitch. I assume they tied into the factory harness and used the same ground.
Thanks, Don

bruster · Dec 10, 2008

That could be a clue there. One of those cords has bad connections or rotted wiring, it can effect the other section. Check all wire connections first

Let us know what you find!

DScott · Dec 10, 2008

(quoted from post at 05:44:27 12/10/08) That could be a clue there. One of those cords has bad connections or rotted wiring, it can effect the other section. Check all wire connections first

Let us know what you find!

Thanks! Will do.
Don

T_Bone · Dec 10, 2008

Hi DScott,

Like the other guys, the first thing I'd do is add a external ground and see if that solves your problem.

If not I'd look for a single strand touching the blinkers inside the plug.

T_Bone

Dennis Benson · Dec 10, 2008

Besides looking at the ground on your truck, if you have round contacts in your socket they may need to have a small screw driver inserted into the terminal to spread it a little. Check inside the plug to see if the wire is making a good contact in the terminal. Solder ends of wires before inserting them in the terminal, the screw will tighten against it easier. Use pleanty of dielectric grease in the terminals, and on the terminals, it will prevent corrosion.

DScott · Dec 10, 2008

(quoted from post at 17:59:48 12/10/08) Besides looking at the ground on your truck, if you have round contacts in your socket they may need to have a small screw driver inserted into the terminal to spread it a little. Check inside the plug to see if the wire is making a good contact in the terminal. Solder ends of wires before inserting them in the terminal, the screw will tighten against it easier. Use pleanty of dielectric grease in the terminals, and on the terminals, it will prevent corrosion.

Dennis,
I had wondered about the terminal posts connections. I will spread them a little and get some dielectric grease also. I don't use this truck much. it only has about 30k miles on it and it's a 2004 and it never sits outside so it's hard for me to see how the wiring could "rot" or deteriorate much but something has happened to it. It's supposed to be warmer and dry next week so I'll try to check it out then.
Don

souNdguy · Dec 10, 2008

Bad connections in general, and/or insufficient ground.

I added a seperate ground wire with a QD to all my trucks and trailers, to ensure good grounds.

soundguy

Trailer Lights Blink

DScott

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bruster

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thurlow

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DScott

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bruster

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DScott

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T_Bone

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Dennis Benson

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DScott

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souNdguy

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