In2racn

I have 60k on a 2020 Denali Duramax 3500. Some towing... bobcat skid steers, small camper, snowmobiles... nothing too heavy.... seems like the ride is getting a bit rough lately. At what point should I consider new shocks? What are you guys seeing for life from stock shock absorbers? Thanks...

If you hear the actuation, the electric release mechanism needs lube. I would hear the clicking, but the gate would not open. Cleaning and lubing the locking mechanism got it working.

2020 Denali diesel, 60K. When I start the truck in the morning, it wont go over 15 mph. Foot to the floor, zero power. Engine not smoking, no CEL, seems like a dead pedal. A quick stop, shut off and reboot, the truck has power again. Every cold start needs a reboot. Occasionally, even after a restart, at speed it will stutter, downshift and then run ok, Then stutter again.. Almost like it is defueling. Anyone heard of this?

I found it convenient to use the app driven trailer "light test" in the Pro Trailering portion of the My GMC app. It is no longer there. Anyone having the same issue?

Yea, I need to do something... the force needed to disconnect is very close to literally ripping the trailer plug/camera connector port right out of the truck. Regarding the camera connection, it works maybe 30% of the time. I connect the camera... truck off and "sleeping" sometimes I have camera view, most of the times I don't. Cannot believe GM cannot get this right. Has anyone had these issues? Any real solution. I have tried hot connection, cold (truck off) connection, wait for the truck to go to sleep connection... nothing consistently works.

I have 2 different enclosed trailers with GM Trailer cams mounted to the back. I have the camera mounted above the ramp door so I have not worried about the "transparent" trailer thing. I just use the rear camera view. At times, both have worked well, but they are very finicky and sometimes display no video. Now, my snowmobile trailer refuses to display a picture. I have tried shutting the truck off, rebooting, all kinds of things I have seen suggested here to try, nothing works consistently. (Although I am not sure if I have tried reconnecting after the truck has "gone to sleep". Wondering if anyone has found any ideas that work consistently. Another issue I have is the crazy amount of force needed to disconnect the camera from the truck. When disconnecting the camera plug, it feels like I am going to pull the entire 7 pin/camera bumper port right off the truck. I have tried some dielectric grease, some other lubes, most anything to try to lessen the amount of force needed to get the camera plug out of the truck's trailer connector. No real success, it is still very difficult. The round 7 way is fine, however the camera plug on the truck is crazy hard to disconnect from. I see a number of owners here on the forums talking about their dealers replacing the 7-way.... are there known defective units out there? a recall? Even a simple non-camera connection like a single jet ski trailer sometimes require me to wiggle the 7-way plug to get all the lights to work. Maybe a new 7-way/camera plug receptacle would cure all my issues.

I am going to do a 30 inch J pipe to kill the 113 Hz drone noise I get at around 1600 rpm. This is the calculated length to cancel out the sound at that certain frequency. I will let you know how it works.

Be careful with the SOTF... After I posted the above, I saw a video where SOTF is causing the modded ECM's to fail.

Awesome to hear you got it done and are happy. I also experience intense "droning" at around 65 mph. I will be very interested in your results should you try the resonator. The "heavy tow" tune actually has less HP gain than the light tow? Is this because of a loss of torque?

Good luck with the delete. My truck is running well. I wish I never had to delete. My 2020 was extremely quiet in the cab, had enough power and I didn't mind DEF fluid refills. The biggest problem is Check Engine lights... and even the lights don't bother me if they came on like a gas truck. In another words, "Oh ******,another CEL, I need to get that fixed before the next inspection or I need to make an appointment". But no, I HATE when my truck threatens me with limp mode. In past years, it would be 3AM deep in Quebec, 20 below zero, on the way back to NY after a snowmobile ride and I would get the "Speed limited in 47 miles". This should be against the law. I am not sure if it is required of the OEM's to do this, but it is total BS. One time on my 2011, my tank heater went when I was miles from home.... it was 90 degrees outside! No tank heater needed... yet my truck threatened limp mode. If the EPA, Emissions idiots want us to comply, how about making it reasonable? Any way... rant over... As I hinted at, I enjoyed the ultra quiet cab of the 2020... the delete, even with a muffler is certainly more noisy than stock. At certain loads and RPM levels, the truck resonates in the cab, a bit of a droning sound. Going to manual and downshifting gets rid of the howl. It it not a big deal and I have gotten used to it, but I miss my "Cadillac-like" quiet cab. However, on the other hand, under acceleration, passing, climbing hills, it is cool to hear the real rumble of a 500+ horse diesel. I do not have the multi-tune SOTF as of yet. I was hesitant at first. I figured, less options and tunes, less chance of CEL or issues. But, the more I read and hear, it appears the tuners have the SOTF bug-free, so I may add that to my truck. I see you have the cool intake stuff... please keep me posted on how that works and how your tune comes out. Also, I would be interested on what the 5 tunes are on the SOTF.... do they simply alter the HP produced with each tune? Stay in touch, good luck to both of us with our unwarranted $80K vehicles! Well.... $85K after you count the 6 - 8K on a delete. (We need to have our heads checked!)

I had the exact same tank heater issue. It was the second time my truck had Limp Mode warnings in 19k miles. This was about the same time frame as your issues, mid January 2021. They had no idea when parts would be available, and I understand there were hundreds of dead 2020 L5P's sitting around North America. After sitting 3 weeks, I couldn't take it any longer, $1000 a month to sit at the dealer with no end in sight. I had the truck deleted with a lot of anxiety about the warranty. Cost me about $7k. So far so good (about 6k miles on the delete). I have a mild towing tune (550HP) with a 4 inch pipe and muffler. I did not tune it for power, mileage or towing... I tuned it to get my truck back instead of waiting months for parts. Like you, I didnt want to roll coal or race the truck, but I do drive fast and try to keep moving in traffic. I pull snowmobiles, skid steers and dump trailers. With the tune, it certainly has more power, the "dead pedal" is better but still not as punchy as I would like off idle. Overall, I think my deleted LML was more powerful, but that truck did not quite get as good mileage as the L5P. Maybe the 10 speed makes the mileage better? Even deleted and tuned, the 10 speed shifts smooth, although it should improve when they crack the TCM. I recently had to run about 125 miles and was in a hurry. During the trip that included flat and hilly terrain, I ran at around 80 mph on the GPS and broke 100 mph about 3 times making passes. I averaged 26 mpg going a a good clip. Some of these Youtube videos showing multiple 2020 L5P's blowing injectors has me very nervous.

Thanks for the reply. The sad thing about this.... the camera is on a snowmobile trailer. Last season (start of Covid), that trailer was used 6 times. Then stored inside for the summer. Then when I go to use it this past season, it is defective. So in reality, that $500 camera lasted for 6 uses. Last week, before this camera issue, the dealer reached out and asked me to reserve a Hummer EV pickup. Maybe I will get it maybe I wont. But, I put my refundable deposit down on one. I currently have and have owned a number of GMC products that I get from this same dealer. In my mind, a small business owner.... if I have a good customer that has a problem with something I sell, I will go ahead and replace it on my dime to take care of the customer, even if the manufacturer is slow to help out. Then deal with the manufacturer later. GM and this dealer are quickly turning me into a Ford and Ram guy.

Got a 2020 Denali HD 1 ton in September 2019. I purchased 2 GMC trailer camera in December 2019, one for my snowmobile trailer and one for my wife's craft trailer. The sled trailer went one winter fine, trailer stored inside all summer. This December (2020), I noticed sporadic trailer camera function. It wouldn't come on right away, then it would be fine for a short time, then flicker out and not work. Sled season was short but it was strong for the 6 or 7 weeks from late January to first week in March. I was too busy riding to address the camera issue. In addition, it is damn cold to be working on top of an enclosed trailer. Mid March, I contact my GM dealer for a replacement and they tell my I am screwed. The offer to sell me another at a "good deal". Their "deal" is still more than Shopchevyparts.com. In any case, has any one tried GMC direct for help on an issue like this? Between getting a "DEF tank heater" code with limp mode, having no tank heaters in stock and now this camera, I am ready to burn anything with a GMC logo or bowtie.

I have the same problem. 2020 Denali HD... have 2 enclosed trailers, bought a camera for each trailer. My snowmobile trailer camera worked for the first season, an occasional issue, but a reboot would fix it. Now, I have nothing but a black screen with an X in the upper right corner. I tried every fix, reboot, truck off... nothing works. I will try the other trailer to see if it the camera or the truck.

Mine sits waiting for parts - P20C1, DEF tank heater. 20K miles. This is the second CEL with limp mode warnings.

Thanks.... the info from my dealer cannot be more "vague". Service guy - "We do not have a SPAC number yet" The service clerks goes on to say " I talked to the parts guy says he see's the part moving just no one has answered it yet." When I asked him, "Is it moving to us, to our dealership?" His response - "The parts guy said the part is in transit just doesn't know where too did not get a tracking number yet ." In transit to "somewhere". WTF.

Hi Guys! Thanks for your input on my P20C1 tank code issue. That DEF tank/heater combo.... you are fairly confident that this part is simply not available anywhere? Another member mentions "2 or 3 months" before there are parts available? I cannot be without a truck that long. My dealer says he "sees" the part 200 miles away. He goes on to tell me "Unfortunately we do not have a SPAC number yet, I talked to the parts guy says he see's the part moving just no one has answered it yet. The parts guy said the part is in transit just doesn't know where too did not get a tracking number yet ." What's the chances of me getting this part?

This is unreal. So an $80k truck that a company depends on to make money sits for possibly months because of no parts? Who is accountable? GM? The government for making rules the manufacturers obviously cannot reach. I don't understand how the consumer has to pay the price for this BS. I had a 2011 Denali... the first year of DEF. I could understand some growing pains with the early models... but 10 years later? Really? how are these over the road truckers keeping their diesel rigs rolling? If there is truly months of waiting for parts, this truck will be deleted, I don't care where I have to send it.

Thank you for the info. I think I saw somewhere you work for GM? How long has this back order been going on? Do you know the part number? 84996345? Is there any light at the end of a tunnel? Is the tunnel short or very long... scary deal.

As expected, no parts. So my 2020 truck sits while the $1100 per month payment keeps right on going. And of course, they offer me a little ******-box to drive in the meantime. I have a snowmobile trip to Maine and need a truck. I am not a happy camper. Anyone know what part number is needed for the P20C1 Reductant Heater "C" Control Circuit/Open code? 2020 3500HD Denali

Mine just went down with a P20C1 Reductant Heater C code. Second DEF issue in 20000 miles. I will see tomorrow (Monday) to see if I can get in and if parts are available. I told myself I wouldn't delete my 2020 like I did my 2011. I tried to convince myself that "they must have DEF reliable by now", but here we are 10 years later, still unreliable junk. My 2011 was first year DEF, I cut them some slack.... still junk in 2020.

Mine has the exact same issue. They are replacing some parts in my steering column. I am not exactly sure what needs replacing yet, but I will report back after the repair. The noise occurs as the steering crosses center when you steer left and right.

I have, still chimes in with "Check trailer wiring". Then a couple seconds later, the bad connection "reconnects" and I see in the dash - "trailer brakes connected" (no chime). The a second later - "Check trailer wiring" with it's accompanied chime. It will drive you nuts.

Im on the way home with a trailer and evidently somewhere there is a bad connection to the trailer brakes. The damn "check trailer wiring" error CHIMES in every 3 seconds as the trailer brakes connect for a second and then disconnect causing the dash warning and Chime to go off. How can I disable the chime until I can figure out was is wrong with the trailer? The trailer is empty and brakes are not even needed, yet I am ready to take an ax to the dash as the chime will not stop. In the "trailer" settings app on the dash, for my profile on the trailer there is a "electric brake warning" function that you can turn on and off. Neither position stops the annoying dash warning and associated warning chime. Is there a fuse? Where is the chime, I am ready to unplug it, cut the wire, anything to stop this noise. Thanks!

Actually took 2 containers of Blue DEF.... 2.5 gallons each.