Please Explain
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Senior User
Joined: Dec 2007
Posts: 383
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From: PLANT CITY, FL
Please Explain
I have a trailer with a 4 pin connector that the lights do not work on when plugged into my truck, but when plugged into my brother in laws 94 chevy it has running lights? If he hits the brakes the trailer lights go out completely. Any theories?
Of the next Riffraff East
Joined: Oct 2004
Posts: 8,679
Likes: 2
From: Concord NC
You may not have the trailer wiring fuse in on your truck. On the other truck, sounds like a grounding problem. Make sure the ground wire (white) is grounded to the trailer frame and the ground on the truck side is grounded to the truck.
Lead Driver
Joined: Jan 2007
Posts: 6,708
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From: Kiowa CO
You might have more than one thing going on here. Check your fuses on your truck for burnt ones. There are more than one fuse that feed the 4 pin harness. Your trailer may have an short that is causing the lights to malfunction when plugged into the chebby.
On second thought, if the wrong light bulb is installed on the lights in the trailer, that will cause the lights to go out when the brakes are applied as well.
On second thought, if the wrong light bulb is installed on the lights in the trailer, that will cause the lights to go out when the brakes are applied as well.
Hook it, I'll pull it.
Joined: May 2007
Posts: 15,037
Likes: 4
From: Grand Lake, La.
Here is a little something to help you with the wireing. click here. Just something you might want to keep around if you pull trailers.
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Senior User
Joined: Dec 2007
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From: PLANT CITY, FL
I forgot too mention my truck is definitely not the problem I hooke up to another trailer and the lights worked. I thought maybe somehow the trailer in question is grounding thru the chevy but not thru my truck?
Lead Driver
Joined: Jan 2007
Posts: 6,708
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From: Kiowa CO
I found a wire was grounding out against the frame under the tongue of my utility trailer and it took the running lights out and popped the truck fuse. Snoop around the whole wiring run. I found my short at the point where the wires feed thru a rubber grommet and the grommet had fell out.
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Hotshot
Joined: Jan 2002
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From: La La Land
Since late-model trucks all have the 7-pin connectors nowadays, why not scrap that 4-pin trailer plug and re-wire it properly with a 7-pin plug?
It should then plug into any late-model truck.
If you have an early truck, add a 7-pin receptacle to it, anyway.
Use the website that Rick referenced as a guide. Just remember which is the truck side and which is the trailer. Oh, and which is the mating side of the plug and which is the wire side.
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It should then plug into any late-model truck.
If you have an early truck, add a 7-pin receptacle to it, anyway.
Use the website that Rick referenced as a guide. Just remember which is the truck side and which is the trailer. Oh, and which is the mating side of the plug and which is the wire side.
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Senior User
Joined: Dec 2007
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From: PLANT CITY, FL
I got it fixed I thounght about rewiring it to a 7 pin but its not mine. Wejust took my brothers boat trailer and rewired it to a 7 pin. Anyways the issue was someone had messed with it and had everything wired wrong. The groung was actually connected to the left blinker and nowhere did they have the trailer grounded. it is fixed now I still have no idea y my BIL chevvy lit it up?
Hook it, I'll pull it.
Joined: May 2007
Posts: 15,037
Likes: 4
From: Grand Lake, La.
I got it fixed I thounght about rewiring it to a 7 pin but its not mine. Wejust took my brothers boat trailer and rewired it to a 7 pin. Anyways the issue was someone had messed with it and had everything wired wrong. The groung was actually connected to the left blinker and nowhere did they have the trailer grounded. it is fixed now I still have no idea y my BIL chevvy lit it up?
. Ben, it's a Chevy, it will do strange things. Looks like you might need to work on the Chevy. Glad you got it fixed.
Logistics Pro
Joined: Jun 2005
Posts: 4,243
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From: AZ
Great find Rick! If anyone wants a PDF copy of that webpage (I converted it) on wiring trailer plugs...see below.
Here is a little something to help you with the wireing. click here. Just something you might want to keep around if you pull trailers.