Jay P

The 10L90 was used in high horsepower cars and SUVs (higher HP/torque version of 10L80). The HD trucks have the 10L1000 which was co-developed with Allison and is not related to the 10L80/90 which was co-developed with Ford. The 10L1000 replaced the 6L90 used with gas HD trucks in the current generation of the HD trucks.

If you can roll the window down you may be able to look down at the latch and use something to pop the latch. Or you may be able to see the loose end of the cable and pull on it to pop the latch. Not sure about the 24 Silverado but this worked on a 2012 Silverado (bent a hanger to pull on the latch release). ***BEWARE OF AIR BAGS*** Jay

Try this. Programming may be necessary if the vehicle battery has been disconnected or discharged. If the window is unable to express-up, program each express-close window: Close all doors. Turn the ignition on or to ACC/ACCESSORY. Partially open the window to be programmed. Then close it and continue to pull the switch briefly after the window has fully closed. Open the window and continue to press the switch briefly after the window has fully opened.

Did you remove/replace or clean the screen under the oil pressure sensor? When they get plugged they cause all kinds of odd oil pressure issues. Not sure the other issues are related but the screen may explain your oil pressue issues.

Check this out. It caused some weird electrical issues with the 19 Sierra I had at the time. May not be your issue but pretty easy to check. MC-10178357-9999.pdf

There are some GM techs on here who may be able to find out what was done/fixed. Hopefully one will see this and check for you.

I take back this may be the reason. The 2023 Silverado/Sierra are not part of this issue, only the 23 Tahoe/Yukon/Escalade are affected. It's only for the LM2 and the 23 ad newer pickups had the LZ0 3.0l diesel. There was a design change to the cooling system when the LZ0 came out and an updated control valve for the LM2 starting in late 23 models and newer. The SUVs didn't get the LZ0 at the same time as the trucks did. I would want to know it has a good warranty (maybe beyond the factory warranty) before buying. FWIW our 23 Tahoe with the 3.0l diesel has gotten 32 MPG on open interstate across SD & MN on I90 (some areas in SD have an 80 mph speed limit). Also remember that the diesel will need DEF about every 4000 to 5000 miles if you are driving empty/no trailer. The emission systems on the 3.0l diesel are far more forgiving to short trips than the systems on the 6.6l diesel in the 2500/3500 trucks.

Probably this. Coolant Control vale update. MC-11023152-0001.pdf

This worked for my Tahoe today. Just put your VIN at the end (must change VIN in the web browser after pasted). https://cws.gm.com/vs-cws/vehshop/v2/vehicle/windowsticker?vin=1GKS2CKD3RR266985

Found this pic, it may help. Supposed to be a 22 Sierra.

I agree that $600 is way too much for just the transfer case. A good practice if you are going to change it your self is to make sure you can get the fill plug out before removing the drain plug (applies to diffs also). Kind of hard to fill if you can't get the fill plug out.

There is an extended warranty. See attached. N252494003 Bulletin.pdf

Known issue with no known fix yet. https://static.nhtsa.gov/odi/tsbs/2025/MC-11016986-0001.pdf

I wouldn't get your hopes up. Your transmission should already have the updated fluid. The original fluid for the 8 speed was hygroscopic (absorbs water) which is what caused the problem. They replaced it with a Mobil synthetic fluid which didn't absorb water (don't remember the year it was changed but it was around 2020). Other manufactures like VW/Audi have had the same issue with moisture so GM is not alone with this issue. https://gmauthority.com/blog/2019/08/tsb-seems-to-fix-8-speed-automatic-gm-transmission-problems/

The DEF tank level works just like the water level in your RV. There can't be a float in the DEF tank because it's allowed to freeze so the level is not very accurate. There is also a TSB for incorrect DEF level reading (see attached). The file I attached is not the most recent and the TSB does include newer 1500 trucks. MC-10244205-0001.pdf