New TCM and battery, but won’t start

[Lui828]

2019 sierra slt 5.3l 8spd , so last week going to work my truck went into limp mode and just stopped moving after a couple miles, had to get it towed home and got these codes  ( u0101, u0100, p2535) I assumed it was the tcm so I went and bought one online and had it programmed to my vin, I just installed it today with a new battery and the truck doesn’t even start anymore just the dashboard and radio turns also I got the same codes, has anybody had this problem ?

 

Edited August 2, 2024 by Lui828

[repairman54]

P2535 engine-codes.com is a good code resource. 

Possible Causes

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

• Faulty Ignition On/Start Switch
• Ignition On/Start Switch harness is open or shorted
• Ignition On/Start Switch circuit poor electrical connection
• Faulty Body Control Module (BCM)

 

[silveradosid]

https://static.nhtsa.gov/odi/tsbs/2022/MC-10224856-0001.pdf

[19 Denali ultimate]

The "u" codes are module connection error codes and are bullshit. My 19 Denali has thrown these u codes about 3 times now and the dealer never finds anything even though there are codes stored. If this happens again with my 19, I'm tempted to remove and replace all the ground straps with something better, or st the very least clean all their connections very well.

[Brian Bohm]

I’m having exact same problem.  Truck will not crank after installation of new programmed tcm

[silveradosid]

are you sure you replaced the tcm, transmission control module, or was it the bcm or ecm. if it was the bcm or ecm the keys will have to be relearned