Adding a 2024+ gooseneck wiring plug

[AndrewF]

What is the proper way to add a “factory” gooseneck plug on a 2024 HD? The truck seems like it is almost fully prepped with part number 86520227 which brings the wire into the bed. And then I picked up 84056018 which is the plug itself. Problem seems to be that the wires from the 865… harness don’t have a connector on the end to fit into the 8405…plug. 
 

What am I missing? I don’t want to get an aftermarket setup if the truck seems to be 90% of the way there already. Essentially seems that I just need to terminate those wires into a male plug which then connects to the 8405…bed plug. 
 

 

Edited May 14, 2025 by AndrewF

[AndrewF]

[AndrewF]

It seems that I need something like this. Not sure if this specific one fits though

Edited May 11, 2025 by AndrewF

[64BAwagon]

I would look at a plug from Pollak since thats who makes the ones GM uses. Your assumption that you need the make plug for the receptacle is correct. 

[Ry Guy]

 

[AndrewF]

1 hour ago, Ry Guy said:

 

I saw that but sadly part numbers have changed for the 2024-2025s

Edited May 11, 2025 by AndrewF

[Handy]

Similar to what AndrewF said, on my 2024 2500HD, I used 84663240 harness, 84670050 harness, 84166962 retainer, and 25774623 receptacle.  Everything simply plugged together, no individual wiring.  All from GMPartsStore.com for about $152, including shipping.

[AndrewF]

22 hours ago, Handy said:

Similar to what AndrewF said, on my 2024 2500HD, I used 84663240 harness, 84670050 harness, 84166962 retainer, and 25774623 receptacle.  Everything simply plugged together, no individual wiring.  All from GMPartsStore.com for about $152, including shipping.

Hmm so you used the same part numbers as pre 2024 trucks. Interesting, the gm parts websites say those won’t fit my 24 truck. But then say they fit a 2023 equivalent version so who knows

[AndrewF]

Just to bring this to a close, in my situation the Curt 56229 plug worked for connecting my existing wires to the GM bed plug. There may be other/better options out there (though this was Delphi made) but it worked and overall other than the wire connectors that were included seemed well made. 

Edited May 14, 2025 by AndrewF

[fondupot]

@AndrewF I am in the same boat as you were when you made this post. I want to add the wiring provisions in the bed, for a future gooseneck hookup. 

 

Just so I understand: You purchased GM Part 86520227(wire harness) and hooked it into GM Part 84056018 (receptacle). And then used Curt 56229 harness to tie it into the factory wiring under the bed? Sound about right?

 

Have any photos of the completed wiring setup?

 

Thanks in advance. 

[fondupot]

On 5/12/2025 at 9:47 PM, Handy said:

Similar to what AndrewF said, on my 2024 2500HD, I used 84663240 harness, 84670050 harness, 84166962 retainer, and 25774623 receptacle.  Everything simply plugged together, no individual wiring.  All from GMPartsStore.com for about $152, including shipping.

 

When I search for these two part numbers (below), it comes up as a 12v plug receptacle and retainer. Like the one inside the cab for a cigarette lighter.

 

84166962 retainer, and 25774623 receptacle.

[AndrewF]

3 hours ago, fondupot said:

@AndrewF I am in the same boat as you were when you made this post. I want to add the wiring provisions in the bed, for a future gooseneck hookup. 

 

Just so I understand: You purchased GM Part 86520227(wire harness) and hooked it into GM Part 84056018 (receptacle). And then used Curt 56229 harness to tie it into the factory wiring under the bed? Sound about right?

 

Have any photos of the completed wiring setup?

 

Thanks in advance. 

My truck already came with the 86520227 wiring harness which is shown in the first pic above. But otherwise yep I bought the Curt 56229 and crimped the wires to that 86520227 harness, which then plugged into the back of the 84056018 plug. 
 

I didn’t take a pic of it all together but essentially it is the first pic with the screenshot of the curt harness in between. 
 

I think if your truck doesn’t come with the 86520227 harness I think you can get a different one (not 100% sure what part number tho) that will plug directly into the plug. 

Edited November 9, 2025 by AndrewF

[fondupot]

15 hours ago, AndrewF said:

My truck already came with the 86520227 wiring harness which is shown in the first pic above. But otherwise yep I bought the Curt 56229 and crimped the wires to that 86520227 harness, which then plugged into the back of the 84056018 plug. 
 

I didn’t take a pic of it all together but essentially it is the first pic with the screenshot of the curt harness in between. 
 

I think if your truck doesn’t come with the 86520227 harness I think you can get a different one (not 100% sure what part number tho) that will plug directly into the plug. 

 

I'm not sure what harness is currently equipped on my truck. I has the factory tow controller and tow package with the 4 pin and 7 pin hookups on the bumper. But nothing in the bed. 

 

So you're saying in the little box in the bed where the wiring goes, there was already a wire there to hook up to?

[AndrewF]

20 minutes ago, fondupot said:

 

I'm not sure what harness is currently equipped on my truck. I has the factory tow controller and tow package with the 4 pin and 7 pin hookups on the bumper. But nothing in the bed. 

 

So you're saying in the little box in the bed where the wiring goes, there was already a wire there to hook up to?

Mine was the same, only had the hookups in the bumper.

 

Underneath that corner of the bed this wire (86520227) in the pic was already present and coiled up/taped together.  I had to unwrap it and feed it up through the opening.  

 

You'll have to crawl under there and see what you have.  It was fairly obvious to see in my situtation.

 

Edited November 10, 2025 by AndrewF

[fondupot]

So mine had no wiring whatsoever behind that blank. I found a local RV shop that is going to install my B&W hitch and they do all the wiring too. They just did a 2025 2500HD this morning so they are very familiar with the process. 

 

Having it done tomorrow. Easier than me trying to diagnose and troubleshoot the wiring. And I don't have the time or help to install the hitch myself right now. 

Edited November 11, 2025 by fondupot