Fire1382fighter

Hey guys, I ordered a leer 100XL topper for my 2021 3500 AT4. I installed it myself. It wasn’t difficult with the help of a few friends. The wiring was a little more tricky. The 100XL comes with the remote window lock feature. That was the tricky part. After a few days of research and development, I finally figured out which wires are the lock/unlock wires. If you take apart the drivers door sill, there is a covered wire bundle there. In that bundle, there is a 20 gauge gray wire and a 20 gauge brown/yellow wire. Those are the lock/unlock wires. Hope this helps people in the future so you don’t have to beat your head against the wall like I did.

Thanks for the info guys!! I think I’m going to go ahead and order one.

Hey guys, I have a 2021 3500 AT4 with the duramax. I want to install a S&B cold air intake. If I change it, will it throw the check engine light? I know it will on the 1500’s. It says it won’t on the website, but I just want to verify before I purchase it. Thanks!

Hey guys, I have a 2021 GMC 3500 AT4 with the Duramax. I’ve been doing research on adding a S&B CAI and the DPF back exhaust. My question is are they worth the money? I heard with the CAI intake, it can throw a service engine light due to the MAF sensor or something. It would need to be re-flashed by the dealer. Is this true as well? Is the DPF back exhaust worth it? I had a 2012 ram 3500 back in 2013 that I deleted and it made a hell of a difference. Not sure if the DPF back exhaust would make a difference. I would like a deeper sound though. I’m looking at the banks 5” DPF back exhaust if that helps. I do not plan on deleting this one anytime soon. I would like to keep it as stock as possible until the warranty is up. Any info is greatly appreciated. Thanks.

Is your truck gas or diesel? I’m thinking of putting this on mine but heard it doesn’t make much of a difference for the diesels. I would love if it made my truck sound deeper.

I have a 2021 3500 AT4. My audio has cut out twice in the couple months I’ve owned it. No matter what source is selected. Infotainment center still functioned normal both times. I took it to the GMC dealer in Anchorage about three weeks ago because they said there was a recall for it. They did the recall and I’ve had no issues since.

I have the camera on my camper. I’ve never had the issues you are having and it seems like you have tried a lot. If I remember correctly, there are blue o-rings on the camera connector. You might try removing them and seeing if it connects and disconnects easier. If it does, you have found your friction source. Maybe order new o-rings from GMC and lube them up and install them and see if it helps. Hope this helps some.

That’s a nice truck. Is the interior the same as the 2021’s or is it redesigned?

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

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.

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.

I’m having this issue on my 2021 3500 AT4. I just installed the upfitter switches on mine since GMC wouldn’t. Now my steps are intermittent. Did you have any luck finding out why they aren’t working correctly?

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?

GM changed their military discount starting May 1st. They dropped it to $500 flat rate. I bought my 2021 3500 AT4 on 4/30 and the dealership said I got lucky. My discount was $5500 off. If I would have purchased on 5/1, I would have lost out on $5000 in discounts. It stinks they changed it, but unfortunately right now they can’t keep inventory on the lots.

I replaced mine with LED’s from Walmart. I would guess they are Sylvania bulbs as well. I don’t have any issues with mine. They look great.