seamus2154

I was using that wire to trigger my relay, which then turned on my LED lights. So I cut the plug off and wired direct to the relay.

I understand. I have had this adaptive cruise since on 3 GM vehicles now. The 2021 you can actually disable it if desired and have regular cruise. I am wondering if the OP did that by accident. When you hit cruise it does default to adaptive cruise but gives you a prompt on the screen on how to disable it with one button. Maybe he hit it by accident??? And thought he was in adaptive cruise. But either way adjusted to the closet setting is still too far away for me. Cars still change lanes and push you back. That part is very annoying. It will disable, with rain, snow, or mist. But not continue and not stop. So its either user put into regular cruise mode mistakenly or if as he said it happened there is something wrong with his system. Like I said if there is an issue, it clicks off and puts up a message, not full speed ahead.

You guys are ridiculous for blaming the OP driver here. THE ADAPTIVE CRUISE DID NOT WORK AS DESIGNED. If I had it on, I would be waiting for it kick in and slow down also. Then I would realize something is wrong here and hit the brakes....just as the OP did. I like adaptive cruise and use it often. BUT it does seem to slow too soon or closer than the last time sometimes?? So I am always watching the distance. This is not super cruise, or a Tesla, you cant go to sleep! Apparently some comments are from those who do not have or use adaptive cruise and dont understand how it works. To the OP, I have had that message in the DIC usually when its raining and the radar is not optimal. I suspect something interfered with the radar and disabled it. I have never had it not slow, but have had it disable itself and put that warning up....which means you at that moment DONT have adaptive cruise, so adjust as necessary. Which you did. I would try it again on a clear day and see if its working properly at all. A dealer visit is in order.

Looking good! Yep it was the light green wire for reverse. I used the Putco harness which was plug and play and had a reverse wire on plug. Made it a breeze. I was intitially taken back with the price till I received it. Very nice quality and didnt have to cut the wire.

I bought the BAK tri fold hardtop MX4. I had originally bought the BAK revolver rollup. It separated on day one and they wanted to warranty it! NOPE this is day one, take it back. Then went with tri fold BakFlip MX4. High quality works great, locks in each position, does not interfer with tailgate. It is a nice quality piece. At the price point of a new Denali I wasnt going to put 90's tech vinyl roll up top on her! This fits it and matches it perfectly. Install was easy maybe 30 minutes.

But that is an LS based motor, not an LT. The LS engines are a different (arguably better) animal. They routinely go 300-400,000 miles with cheaper easier issues. The LT 6.2 is a hot rod but LT based as it be its not as durable or long lasting as an LS. There are high mileage ones but they have not faired as well as the LS. Just has more going on and more issues long term .

Do a search. This is all over the forum threads. No they are new lifters, and yes the others will fail, fight for all lifters replaced.

They have been around a long time. I had it on my old Silverado and they work great. Ride is uneffected till it sags into the roadmaster spring. Its designed that way. So a little sag but then control and better handling. Easy install, good price point.

I have a brand new 2021 Sierra Duramax. I had the same thing a rattle in back seat area, seemed like near seat belt mounts. We tried everything to duplicate but would only do it on the highway at speed. Drove me crazy! Had my wife back there while driving , we were like crazy people trying to find it. THEN put my 12 year old back there and she narrowed it down to a body seam under the back seat near seat belt mount. But nothing was loose. I put the truck up on the lift and there was a heat sheild under the floor right near that spot on the passenger side. It was bent up on one corner and tapped and vibrated at highway speed!!! Sounded like it was clearly in the truck, but it was right under that spot underside of the vehicle. Good luck

My constant 12V is off the trailer plug to the relay. The trigger for reverse is from the Putco harness that is inline to taillights then to relay. Triggers and powers up reverse light perfectly, nothing times out or trips, and no issue with cross traffic or parking sensors. The extra light does not wash out the backup camera if anyone is concerned. It adjusts to the extra light. Might be under the threshold of the BCM but works perfectly.

Thanks Guys! All good input! The Putco harness was a real quality piece. Had a wire for reverse which I used for my relay trigger. Only had to tap into the 12v constant on the trailer harness which is the only live wire on that harness in 2021 with no trailer hooked up. Came out great, this is what forums are for...help. Thanks guys!!!

Happy it worked! I ordered the Putco plug in harness which will get me the trigger for the relay on backup lights. I dont know if it will have a constant 12V but can still tap the trailer plug as that has 12v only. I mounted the lights just awaiting harness. I did use a test light in the taillight harness and it seemed to be the light green wire as you said. My concern was it was very light gauge i assume due to the LED not needing much?? The Putco harness was more money than the LED light pods!! LOL

LOL Tire salesman would be a bit of a pay cut! But if you find any coupons or sales let me know, I need to switch my wifes GLC over to Michelin asap! It came with RF Pirelli Scorpions....horrible tire and ride.

If you like passing other cars and going from 70 mph to 100 quickly you would notice a big difference. The 3.0 shines everywhere else. I loved the 6.2 it was an animal. I tow a race car, but wanted fuel mileage also. The 3.0 is an all around great package. It pulls strong and is very torquey in town but will not pass on the highway like a 6.2. That is the only downside. I drive 78-88 all day and its no slouch...but its no 6.2 in that one category. The mileage is crazy good. I get 24 mpg driving like an idiot. I get 28 being nice, and have gotten 30 being crazy. Very happy with the 3.0, does almost everything well. The 6.2 is a rocket ship hard to compare. So if that is what you like, and dont mind the fuel prices stay with the 6.2.

That is surprising. It is rare to have a bad Michelin tire but my tire guy said he has seen it a couple of times. Nothing like other brands. Michelin is usually always the fix. I would take the truck to a known quality tire shop with a roadforce balance machine. It will identify a bad rim, or tire or balance it out correctly. It may be that simple. good luck

UPDATE: As per Putco the 2021 is different as far as the trailer plug lighting up without a trailer plugged in. The 2021 needs to see the constant draw from the trailer. The good news is this blade harness WILL work as needed!!!! Thanks Transient !Thanks Zelas ! BIG Help!!!!

Wow, this looks perfect! I put in 2021 and it states it does not fit a 2021 Sierra 1500!!! I am going to call them Thanks for your help, hoping website just isnt updated to 2021?

Thats a great option for not cutting the wires, thanks. I dont know if the 2021 Sierra Denali is different that the trailer plug is not active other than a 12V when a trailer is not plugged in. None of the pins light up without a trailer plugged in. Never came across this before. I assume its due to the new trailer package and interaction with the screen?? So if that plug is not live I cant see how the T would work on the 2021???? As soon as the trailer is plugged in, it pops up on screen and prompts for the light test which works perfectly and all trailer lights work. Unplug it and test those pins and nothing but the 12V works. There is a schematic on the plug cover if you look. So i am assuming its going through a module???? Thnaks for the input

Thanks Jason, I assume 2019-2021 should be the same??

No one knows if this truck has a module running the trailer plug or rear taillights ?? Nervous to just use that light green reverse tailight wire as a trigger for the relay and destroy a module. This is the stuff I hate about my German cars, cant mod a thing without a computer problem.

I too have a 2021 Denali Duramax with 22's. Same thing slight vibration, drove me nuts for 600 miles. I had similar issues with three of the previous generation truck. It was always the tires. The solution was to switch to Michelin defenders each time. So I sold off my rims and tires as a package and bought new Snowflake rims and Michelin Defender LTX. Smooth as glass. Also rides nicer on the Michelins. The Bridgestones were terrible just in ride quality alone, certainly didnt want to start chasing down bad tires too, which is always the case with Bridgestones.

Hey Guys! I have a New 2021 Sierra Denali 3.0 Duramax. Love it so far and have been sorting it out nicely. I have had 3 of the previous generation truck. I always mount LED rear backup lights on the rear bumper as some of the places I race have no lights in the parking lots. In the past I pull 12V power and the reverse light as a trigger wire for the relay for the lights, off the trailer wire connector. Well.......this 2021 does not light up that plug unless the trailer is connected. Once you plug in the truck recognizes a trailer is hooked up. For some reason there is 12V that is on but none of the other wires are live till a trailer is hooked up. I thought something was wrong so hooked up the trailer and boom everything then works and the display states trailer hooked up. So...I can get the 12v for the relay but now I am trying to find which wire on the rear tailight harness is the reverse lights? Appears to be the light green one I think?? But this truck is all LED and its a very light gauge wire. Does this truck have a LCM like the german cars.? Light control module. Will it sense a larger load and screw up something?? Pretty common with german cars. Also afraid to mess up any modules? I have wired 10 different pickups this way but the new generation is definetly different! Any advice for a trigger wire on relay?? Is that much of a load to the relay?? Thanks

Any luck solving it??

I had the same issue with my dog recently traveling cross country. We rented the 2021 suburban. We were told and it did work, to when you first start the vehicle to hold the start button till message came up on the DIC. cant remember what it said but something about auto shutoff disabled. I hit ok and that doubled the time to 30 minutes. We set the timer on our iPhones and would just come out of the restaurant to reset if needed. I dont have my new 2021 Sierra here to check but this did work on the suburban. Good luck.

Wow, happy to see your post today!! I am contemplating this exact mod. We just rented a 2021 suburban and I loved the screen. Camera resolution seemed much better but the bigger screen was much nicer. A week later my 2021 Sierra came in and a feel deprived of that 10" screen!!! Knowing GM, I figured the plugs would be the same and I would mock up the screen to look factory. Great work so far, following your solution closely I really hope you get a fix, this will be an awesome upgrade! Thank for posting