Trailer Lights

[WhiteDiesel]

I tow a 16' flat bed everyday. One day the running lights stopped working. Then later, the left turn lights stopped working. I thought the trailer had problems and would get around to it when I could. Finally, I plugged it in to my cousins F**d and all lights worked perfect. So I checked the connector, and all fuses and they were OK. Anybody have this problem, or know where to look?

[MAV]

Sounds like a ground problem. Most of the time a ground problem will pulse or flicker the lights. Yours went compltely out eh?

[hd90rider]

I agree with the ground being the culprit. Also you might want to take the recepticle apart on the truck. Mine had a loose connection there. It comes apart very easily, by pushing on the clip, behind the mount plate under rear bumper, then you can twist the outer part to remove from mount. Check for corrosion on pins. Hope this helps. :rolleyes:

[96ccdd]

I AGREE WITH THE GROUND PROBLEM.ALOT OF TIME WITH THE SMALLER TRAILER THEY RELY ON THE BALL AS A GROUND CONNECTION.

[BigLakeDMAX]

Just making sure you know that our trucks have separate fuses for trailer lights - in the fuse box under the hood. Truck lights will work just fine but no trailer lights if one of these blows. If you've checked these, then I'd start with the connector.

Good Luck!

[Swamp Rabbit]

I just bought a new Anderson 25' Gooseneck trailer. All trailer lights worked fine on test monitor. However the left turn signal and brake lights would not work when hooked to my 2002 Dmax GMC 2500HD. Got home and hooked the trailer to my other truck a 2000 GMC 2500, had exactly the same lights not working , the left turn signal and the brake lights. Hooked the trailer up to a Ford and all lights worked perfectly. Does anybody know how the trailer light wiring in a GMC truck differs from the Ford setup? How can I correct this wiring problem?

[Vette Racer]

If you are using the adapter I found that Chevy and Ford use different ones due to different wiring. Had to get one just for GM.

[Swamp Rabbit]

Vette Racer,

I didn't get an adapter which I bought my truck. Do you perhaps remember the part number of the adapter you use on your 3500 D/A to make the trailer wiring work. It would be easier for me to find one for my truck.

[Vette Racer]

Swamp Rabbit

You can go down to any towing or auto parts store and buy one. They run around 15 bucks out here. Just ask for the one for a GM and tell them what it needs to connect to, such as a 4 pin flat or a 6 pin round, etc. Whatever you have on your trailer.

Something just crossed my mind, If you are hooking up the trailer now, do you already have the large 7 pin connector on your trailer that fits the plug on your truck. If so then the adapter isn't the issue. It would have to be miswired or a grounding problem as others have posted to above. I don't know about ford but Chevy requires a separate ground wire in the plug for correct grounding. Hope this helps.

[Swamp Rabbit]

:confused: Vette Racer,

I guess the adapter is not the issue since the gooseneck trailer connector uses a 7 pin & the GMC truck has the factory installed 7 pin wiring harness. With both my GMC trucks I seem to have the identical problem.

Since the trailer lights work when just the wiring connector is hooked to my Ford truck without actually hooking up the gooseneck ball, the grounding requirement must be supplied from some other source not the ball connection when using the Ford.

I need to find out how GMC satisfies the grounding requirement when pulling trailers. I asked the mechanic at my local Checy dealer, but he didn't have a clue.

Thanks for your suggestions.

[DonG]

Swamp Rabbit,
Since you have the seven pin connector and it works with the Ford, then I believe that the only explanation is a blown fuse on the GM Trucks.. Yes, both of them. On my 2003 GMC, the left turn signal/brake light of the trailer is fused with a mini fuse inside the drivers door jam. Open the driver's door and open the fuse box revealed near the hinges. Find the bad mini fuse, I think it is a 2 amp fuse.

All trailers need to be wired the same since they must hook up to several truck models. I have found the seven pin connector to be very consistant. One of the seven wires is the Ground, not via the hitch.

Don

[Swamp Rabbit]

smile.gif Don G.

Thanks for the suggestion. I going away for the weekend, but I try your suggestion on Monday when I get back.