Sierra 3500 4 Pin Trailer Plug

CalN · July 29, 2020

Anyone with a Sierra 3500 knows of a mod to add a permanent 4 pin plug on the truck. I'm currently using a 7 pin to 4 pin adapter for my trailer and I keep losing it so I had to buy it 3 times already. I need a permanent solution so I don't need the adapter.

Pastusak.t · July 29, 2020

26 minutes ago, CalN said:

Anyone with a Sierra 3500 knows of a mod to add a permanent 4 pin plug on the truck. I'm currently using a 7 pin to 4 pin adapter for my trailer and I keep losing it so I had to buy it 3 times already. I need a permanent solution so I don't need the adapter.

Just a thought, maybe convert the trailer to a 7 pin? I converted my boat trailer to a 7 pin so I didn’t have that problem. My old truck had both but 7 pin seems more common so that’s what I did to future proof.

CalN · July 29, 2020

I can't convert the trailer to a 7 pin because there are 2 other people that I share that trailer with and they don't have a 7 pin on their trucks.

greatmizzou · July 30, 2020

Just get a 7 pin 4 pin combo plug?

CalN · July 30, 2020

Can't get that either because the 3500 have have trailer camera plug together with the 7pin plug. If I remove that to replace it with a 7pin + 4pin combo, I lose the trailer camera plug.

kf9yr · July 30, 2020

On my small utility trailer that I share with my brother I opened up the 7 pin connector and spliced in a short 4 pin pigtail. You need to keep the unused connector covered when the other one is plugged in...

As you can see from the picture he broke the 7 pin the last time he used the trailer and I will need to put a new one on.

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CalN · July 30, 2020

Simple solution. I'll definitely do that. I prefer doing this rather than modifying the truck. Thanks.

Lostboy792 · July 30, 2020

Another option we use at work because everyone looses adapters. We wire in a separate female plug on the trailer with the 4 pin coming out of it as a male plug. this way you have to have the 7 pin male plugged in and it is protected from the elements. Little extra work but somehow that is a system they haven't broke. Had some operator error when they forget to plug the other one in but that didn't surprise us