newdude

OP put new ones in: Alternator shorting wouldn't cause a lack of power when keying the ignition to accessory or run. You can straight up unplug the alternator and the car would still power up and even start.

That could very well have easily been from transport damage. You'd lose your $hit if you see how some of these cars come off the carrier needing work.

No key on power = no DTCs. I'd pull the underhood fuse box as these are known to get nasty with corrosion. See how things look there. I'd suspect internal damage as well to it.

Judging from the rust, that's impact damage that has spread and has been rusting out the roof. Something chipped the paint right at the windshield edge where the heavy rust is and its just been spreading. The rest of that roof looks like bad sun damage and lack of protecting it, or some sort of acid rain damage.

So when you put the key in and turn it on, do you have anything at all? Radio? Lights? Or when you key it on its dead? Or is everything working and it won't crank?

Very true. However. GM did give those trucks with the single speed case Terrain Mode. Terrain Mode mimics 4LO minus the gear reduction and torque capability. It uses the ABS/braking system to perform the operation. It also gives these one pedal driving (sort of) when in Terrain Mode via the active brake during throttle lift. Does it have its limitations over a true 2 speed case? Sure. But it works.

Yea the 1.5T has been fairly stout. The one Achillies heal? The vacuum assist pump. Its driven off the end of the camshaft and is oil fed for lubrication. Clean oil is a MUST. If the pump fails and locks it can shear the cam end or cause the engine to jump time. 8 speed has some teething issues. First few months of production they had bad bolts holding the pump to the case and they'd leak ATF with like no miles on them. Otherwise its electrical snafus. Telematics modules which are being addressed with updates, software snags, etc. CVT is RIP for 2027 also. FWD and AWD go 8 speed only. New 2010? Oh yea. Second year at work they were showing up. Was a breath of fresh air in terms of how they looked, how they felt (interior feel and quality). Time did not treat that generation well however, neither did bankruptcy. At all. The 3rd gen 2018 Equinox made up a LOT for where the 2nd gen faltered.

There's a new PI on 2023-2026 L3B shudder. Possible faulty front oxygen sensor. Dealer can pull up PIP6060A and give it a read.

Also here's the drive cycle for a 2021 Yukon with V8. DO NOT USE THE CRUISE CONTROL WHEN RUNNING DRIVE CYCLE!!!!!: Warning: Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage. Note: You have completed this procedure when all parameters display Complete. Short stops for traffic will not affect the procedure. Note: Do NOT use cruise control during this procedure. Ignition/Vehicle » Off — For greater than 8 h Verify the scan tool parameter: Cold Start-Up = Yes If not the specified state Ignition/Vehicle » Off — For greater than 8 h & Repeat this step If the specified state Ignition » On / Vehicle » In Service Mode — For 1 min Engine » Idling — For 2 min Drive the vehicle while maintaining the following conditions for 20 min: Part Throttle Vehicle Speed = 24 to 97 km/h (15 to 60 MPH) Safely stop the vehicle Operate the engine/vehicle within the following conditions: Accelerate the vehicle to 64 km/h (40 MPH) Accelerate the vehicle from 64 to 97 km/h (40 to 60 MPH) @ Throttle position between 10% and 13% Release the accelerator pedal and let the vehicle coast down with the brake pedal released — For greater than 20 s Accelerate the vehicle from 64 to 97 km/h (40 to 60 MPH) @ Throttle position between 13% and 16% Release the accelerator pedal and let the vehicle coast down with the brake pedal released — For greater than 20 s Accelerate the vehicle from 64 to 97 km/h (40 to 60 MPH) @ Throttle position between 16% and 19% Release the accelerator pedal and let the vehicle coast down with the brake pedal released — For greater than 20 s Accelerate the vehicle from 64 to 97 km/h (40 to 60 MPH) @ Throttle position between 19% and 22% Release the accelerator pedal and let the vehicle coast down with the brake pedal released — For greater than 20 s Accelerate the vehicle from 64 to 97 km/h (40 to 60 MPH) @ Throttle position between 22% and 25% Release the accelerator pedal and let the vehicle coast down with the brake pedal released — For greater than 20 s Maintain steady state throttle at 89 km/h (55 MPH) — For 10 min Safely stop the vehicle

Do you have any DFM defeat devices like the Range modules?

Actually. Wait. I just re-read your original post. Are you talking from INSIDE the truck you have to hit unlock? Or from the key fob? I had assumed from the key fob. IF you are talking the inside unlock button, I assume you are shifting to park and its not unlocking the doors? If so, that is changed via the settings page in the radio. Go to SETTINGS, then VEHICLE and then it should be under LOCKS or DOOR LOCKS or something like that.

Just pull the inside door handle. It has mechanical override to the lock.

DISREGARD! MISREAD ORIGINAL POST!

The engine was done as part of the 6.2 recall? You'd have to see if your VIN also has the 6.2 engine special coverage on it. Coverage number is N252494003. If you have this, your engine is covered under this and NOT the GM replacement part engine warranty which is 3yr/100k from the date of install. The 3yr/100k mi warranty is in effect for non warranty purchases. This is not any different if it was replaced under warranty without a recall or special coverage. So if you had a 5.3 and it popped at 3 years in at 50,000mi during the 5yr/60k powertrain, the replacement engine would not get the 3yr/100k, and instead gets the remainder of the 5yr/60k as coverage. So N252494003 gives 10 years or 150,000mi of coverage, which ever comes first, starting at the vehicle in service date. So if your in service date is 01/01/2022, N252494003 gives you special coverage of the engine until 01/01/2032 or 150,000mi, whichever comes first. So if your start date was 01/01/2022, you'd have left 5 years and 4 months (lets round to august 1st), or 62,000mi left of coverage. So you need to know your in service date to know how much coverage is left.

More than just programming. Wiring (different chassis harnesses with and without JL1 brake controller), modules, programming.

Sometimes these updates can disable or enable settings in the car. Did you check to see if the park assist is all turned on in the settings?

Part is $233.87. Not sure where $900 came from?

It happens. Someone peeled it. Someone swapped it with a junkyard one. etc.

Parts department or service department at the dealer.

No. Idea. That's just where GM set it to. Why?

Rise more slowly? Debatable. It would run slightly cooler, yes if anything after adding the thermostat delete kit from PPE. PPE makes a larger front aux cooler which they "claim" will lower temps 45 degrees but I have not used it. IMO, especially in cold states, I would not want to mess with the first cooler, the oil to water one. Cold states, you want heat in the transmission for it to shift properly, and you don't want moisture in the ATF. Ideal temps for automatic transmissions to do their job the best is 175-220F. Hotter than 220F you start heading towards fluid degradation and shortened fluid life/service intervals. 240F can start varnishing things like the fluid, clutches, etc.

We've done a bunch of them. Very common failure. They don't sell the park position switch separate from the shift control assembly which is stupid, because they ended up selling a switch on some other products like 2016-2019 Malibu, 2018-2019 Traverse, 2019 Blazer, and another car or two as those were having the same issue for years (but these have a console mounted shifter not column mounted).

It is working as designed. NHT and non NHT trucks have the same exact transmission cooling setup. NHT just gets a larger radiator. The transmission cooler loop on these is as follows. -Transmission out goes into an oil to water heat exchanger (item #1 in the first illustration below). This exchanger has engine coolant opposite the transmission fluid and uses engine coolant to warm and then regulate the transmission fluid temperature when its in the operating window. - From the cooler it goes to a thermal bypass valve (item #11 in the 2nd illustration below). If the ATF has not reached the temp to open the bypass (194F), it loops back. - When it reaches 194F, the thermostat opens and ATF then flows out to the oil to air auxiliary cooler (item #17 in the 2nd illustration) at the front of the truck. From there it goes back to the transmission. Your only fix would be to swap for the PPE thermal bypass delete block which will open the loop to the aux cooler all the time. It will STILL run warm, probably 170-200F, but that's as low as you'll get it as its still flowing through the oil to water exchanger.

That's the proper range for the gas 10 speed with the thermostat still in the valve body. TBV opens at 143F. 3.0 Duramax runs different temp.

The exchanger is bolted right to the driver's side of the transmission. Would I go as far as to call it a heater? No. Does it aid in warming up the ATF to reduce friction as quickly as possible? Yes. What's the internals to it? No idea. Never cut one open. However, it's primary role is maintaining transmission temperatures once up to temp. No different than an oil to water exchanger for an engine oil cooler setup like GM uses on say 2010-2024 Camaro with V8, or 6.6 Duramax. Gas 10L80s (so 1500 truck with gas V8) have a thermostat in the valve body but not the cooler lines. 2019-current. 3.0 Duramax with 10L80 don't have a thermostat in the valve body. They have one in the lines going to the auxiliary cooler. 2020-current.