railguy777

The last couple of times that I started my truck there was a message on the screen that "Update failed" When I try to update manually it says "no update available " Anyone have any ideas what is going on here?

Got this from the owners manual. Apparently if you are not driving aggressively it returns to normal after a short period. When you enter this mode you will immediately feel a down shift. In this mode, the vehicle also monitors driving behaviors and automatically enables Performance Shift Features when spirited driving is detected. These features maintain lower transmission gears to increase available engine braking and improve acceleration response. The vehicle will exit these features and return to normal operation after a short period when no spirited driving is detected

I found this on the Husky website. Looks like it might be what you are looking for. https://www.huskyliners.com/Wheel-Well-Guards-Wheel-Well-Liners/2020/gmc/sierra-1500

I had this same problem in my 2017 Acadia. I did not get it every time but was always worse when I parked on an incline .The dealer replaced a transmission sensor and the problem went away.

I have a 2020 SLT with a block heater. There is no thermostat in the cord. It must be in the block heater itself. I checked the cord with and ohmmeter and it always conducts. Plugged my heater in when it was -15 C and no current draw. The other day it was -21 C and the current draw was 3.5 amps. So the thermostat must be set somewhere around -20 C.

Today it was -20 C . Plugged in the block heater and it worked. Current draw is 3.5 amps. Glad it works but still not impressed that its has to get so frigging cold before I can make use of it

Welcome fellow Canadian. I am also from northern Ontario, although not living there now. I have the same model truck as yours but I have not experienced the problem you are having. Hopefully your dealer can do something for you, keep us posted.

Do you happen to have the TSB number?

Mine does it as well. Only in reverse when backing out of the driveway, after that nothing

I have the 5.3 .It started ok in that weather just wish I could warm it up before. I don't like not having the option

My truck came with a block heater. It was -20 last night here in Ottawa and no more than -15 today so I thought I would plug in the block heater and see how it worked. I plugged in the heater cord that came with the truck and checked the voltage =120 v. Was curious about how much draw there is but my amp probe showed zero amps when plugged in. I checked the continuity of the cord, all good. I checked the resistance of the heater at the plug on the truck , it shows open circuit. I read on other posts about block heaters that the thermostat is in the cord itself. It appears that GM has moved the thermostat into the heater itself on the new models so that the cord cannot be tampered with. For me I would just like the heater to work when I want it to, not when GM feels its necessary, I think -15 is cold enough to warrant use of the heater. Attached are pics of the cord that came with the truck -2020 Sierra SLT

My truck came with a block heater. It was -20 last night here in Ottawa and no more than -15 today so I thought I would plug in the block heater and see how it worked. I plugged in the heater cord that came with the truck and checked the voltage =120 v. Was curious about how much draw there is but my amp probe showed zero amps when plugged in. It appears there is no load Just wondering if anyone else experienced this and if there is something I need to do under the hood to connect the heater .

I have been playing with sport mode recently and I have noticed and increase in fuel economy along as I can remember to select when I start the truck. I find especially in city driving it gets the beast up to speed quicker so I don't have to stay on the gas as long.

Just wondering why all the truck leveling? Is there a practical reason or is it just aesthetics ? If it is actually better does GM or any other truck manufacturer offer it as an option?