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2021 GMC 3500 AT4 Power Running Boards

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On 6/28/2021 at 7:46 PM, Fire1382fighter said:

Hey guys,


I picked up my 2021 GMC 3500 AT4 last week. Today I wired up my upfitter switches. Now my power running boards do not work correctly. Anyone have this issue? 


I guess not......

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  • 2 weeks later...

I live on a remote island in Alaska and there is no dealership here. I took it to a local shop today and they pulled the body control module codes. The codes are B051C 62, B051D 62, B051C 63, and B051D 63. They all have to do with the Assist Step Control Module. Unfortunately GMC will not pay to have my truck shipped to the stealership. Its about $2000 round trip to take it to Anchorage where I purchased the truck.

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The upfitter switches.  Were they factory ordered with the truck or you bought all the GM parts and installed?


If you bought and installed, did you reference these documents:  

UI Bulletin 153c.pdf (gmupfitter.com)  and  UI Bulletin_147b Snow Plow power provisions.pdf (gmupfitter.com)


Have you installed any accessories that are controlled by the switches?  If so, what and where?

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They were factory ordered parts. I followed the service bulletins and the write up in this forum. I never hooked anything up to the switches. I just wanted them working in case I bought something to hook up to them. After the running boards started messing up, I removed the whole upfitter harness and junction box to see if the problem would go away. It did not unfortunately.

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For what its worth.  I have the power running boards on my AT4 installed from the factory and mine act up from time to time.  They work for the most part, but sometimes they won't deploy properly when I open the door to get in or out. I just close the door and reopen it and then they deploy.  No biggie, but just an annoyance for something that I paid so much for.  They should deploy correct every time not just "most" of the time.

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On 7/13/2021 at 3:47 PM, Fire1382fighter said:

HiggySTL, I completely agree. Have you talked with any dealers about it? 


Yes, when I went in for my first oil change I mentioned it to them.  The tech told me that a lot of the new trucks come from the factory with the sensors dirty as heII.  So he said they will look at it and clean them really good and that should fix it.  It didn't fix it.  it doesn't happen often, but it still won't deploy right on the passenger side sometimes.  maybe my wife whips the door open to fast.  hahaha!  Who knows!

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  • 1 year later...

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