swathdiver

Well, it could be a coincidence and the blower motor resister died and needs replacing.

Get a Tech-2, your truck was designed to be worked on by it, it will pay for itself in the first repair or near so.

You can press a button between the cigar lighters to turn park assist on or off. Try that and see what happens.

Did you put the old radio back in to eliminate the chance that the new one caused the problem?

As clean as you keep your fluid Marty, I doubt it. Mine is almost there too. Never seen anything about it or how it works save for that explanation given to me once. Just stumbled across it while exploring the Tech-2.

The first sign of trouble usually occurs around 160K miles when the solenoids need to be rebuild in the TECHM and this can be done on your kitchen table. Change the fluid before 50K and it will last a long long time. Not sure about the T1s, the K2s introduced a thermostat to keep the fluid temp at 195 like the coolant, bad for long life, get rid of it if you can. On my 900, there is a place in the computer to enter the kind of tires you are running. A technician on here said it was to adjust how the brakes operate if I remember correctly. Using a Tech-2, it knows it has Load Range C tires and at what air pressure and the truck stops on a dime, about 130 feet or so from 70.

Timken.

You may have inadvertently had your truck tell you about a previous tamper condition too. See page 35, left side of that book.

Well, it wasn't the transmission that failed then, it was the converter! 6L80s are very reliable but were made less reliable when GM put the thermostat on them to help with emissions. Get rid of it and change the fluid every 40K miles or less if towing a lot and they'll last a long time. Average life in a GMT900 is about 170K miles and that is usually just the solenoids that need rebuilding which costs $100 plus fluids and you do it on your kitchen table.

Sounds like the Shock Sensor doing the warn away. See page 34 here: https://chevytrucks.org/wp-content/uploads/2020/07/2020-Chevy-Silverado-1500-Owners-Manual.pdf

I did this for years with a '96 F-150 with a 302, never an issue, fired it up at 5 AM and the thing ran all day I got home around 4 or 5, never shut it off in between. Run my truck the same way, about 200 hours between oil changes, same with the 3208 Cat in the old dive boat.

You're not going to hurt your fuel pump by refueling when the light comes on, there is still plenty of fuel on board for that. At 13 MPG you can still easily attain 275 miles per tank and if towing, you're getting what, about 8-9 MPGs? That's about 175 miles per tank.

Looks like a massive vacuum leak on the left bank of cylinders, check the intake gasket.

Your tank has a 26 gallon capacity. When the tank is on: E = 0-13% fuel remaining or 0-3.1 gallons (2.5V or 197-250 ohms) 1/4 = 30-35% fuel remaining or 8.7 gallons (2.2V or 150-190 ohms) 1/2 = 50-55% fuel remaining or 13.5 gallons (1.6V or 118-140 ohms) 3/4 = 72-78% fuel remaining or 19.7 gallons (1.25V or 83-110 ohms) F = 88-100% or 24.5 to 25.9 gallons (1.0V or 40-66 ohms) Low Fuel Indicator On = 11-17% or 4.3 gallons (2.4V or 208-218 ohms) Low Fuel Indicator Off = 14-25% or 5 gallons (2.3V or 195-206 ohms) On a normal system, when the light comes on you should be able to take on 21-22 gallons of fuel. In normal city driving a Denali like yours should average about 14 MPG and go about 300 miles until the light comes on. Another 100 miles or so for an all highway mileage trip. In my older GM cars, they would stay on full forever and then swing over towards empty. On my 2009, the needle moves off of full quickly and once down near empty stays at 11% for 50-100 or more miles. My tank is 31.5 gallons and it has never taken more than 29.76 gallons and the average fill once the light comes on is 26 gallons. So how far are you travelling between refueling events? Have you run it down to the light and then filled it up shortly after? If so, how much fuel did she take on?

On a GMT900 with the Tech-2, which occurred first; CTD Trigger History 1 or CTD Trigger History 2? Is there a manual that explains how the Inclination and Tamper sensors work, or the basic Content Theft system and how it reports information on the Tech-2?