2020 l5p issues after swapping tcm

engine reduced power all tc/esc lights on truck gear indicator doesnt work(wont show PRNDL) has a lot of codes had to disconnect batteries to shut truck off followed their instructions on swapping tcms
infolog below


2024-03-24 9:56:42 PM
VCM Suite Product: VCM Scanner 5.1.2449 Beta

Operating System: Windows 11 (build 22621)
Microsoft .NET: 6.0.28, 4.7.1 or later
CPU: Intel(R) Celeron(R) N4020 CPU @ 1.10GHz
Available Memory: 1,189 MB
DpiX: 96, DpiY: 96

OS Database: 2022-10-11
OS Mods Database: 2022-10-11


Device ID: 2181815585
Credits Purchased: 8
Credits Used: 8
Credits Available: 0
Licensed Features: Pro Feature Set,

[Specific Controller]
GM E41, 3A20070200700085, (8)


ConnectionMethod: USB
ID: 2181815585
HardwareVersion: 2.1.2
ManufactureDate: 2023-08-03 7:09:14 PM
PartNumber: 6250
FirmwareVersion: 5.3.45
FirmwareStageName: Release
FirmwareControllerGroup: 0
PoweredOnTime: 00:01:59
VehicleConnectedTime: 00:01:57
VehicleDiagnosticConnector: 1
Bluetooth HardwareVersion: 2.3.0
Bluetooth FirmwareVersion: 1.0.0


Protocol Info: ISO 15765-2: Standard 11 bit Normal, J1962: CAN 500 kb/s

ECM: 7E8, CAN, ECM -EngineControl - E41, GM, 2017+ 6.6L Duramax
VIN: 1GT49WEY9LF257670 - 2020 GMC Sierra 3500 Denali, 6.6 L, V8
Serial: 3A20070200700085
Programmed State: Fully Programmed
Boot OS: 12723940
OS: 12718488
Calibration IDs: 12718488, 12719455, 12719379, 12666733, 12678346, 87836557, 87836559, 13536793, 13526562, 13530651, 13536797, 12719473, 12719572, 12719540
Calibration VNs: 00007525, 00009034, 00007EE5, 0000FB1D, 00009661, 0000F5E9, 0000900D, 000049C1, 000046DC, 0000AAA8, 000046B1, 00006C91, 00005617, 00004AF4
Basic PIDs: 67
Trouble Codes:
P0700 - Transmission Control System (MIL Request) (Pending, Current)
P1919 (Pending, Current)
U0101 - Lost Communication with TCM (Pending, Current, Permanent)
Controller Type ID By OS: 41

None: 7EA, CAN, TCM -TransmisCtrl - T93, GM A10/Allison 2019+
Serial: 61230740000X0076
Boot OS: 24296531
OS: 24295683
Calibration IDs: 24295683, 24042985
Calibration VNs: 00005D42, 00009C0D
Basic PIDs: 4
Trouble Codes:
P27A7 (Pending, Current, Permanent)
P27AA (Pending, Current, Permanent)
P27AB (Pending, Current, Permanent)
P27AC (Pending, Current, Permanent)
P27AD (Pending, Current, Permanent)
P281B - Pressure Control Solenoid "H" Control Circuit/Open (Pending, Current, Permanent)
U0100 - Lost Communication With ECM/PCM A (Pending, Current, Permanent)
P182A (Pending, Permanent)
P182B (Pending, Permanent)
P182D (Pending, Permanent)
P182E (Pending, Permanent)
P1839 (Pending, Permanent)
P1840 (Pending, Permanent)
P27A8 (Permanent)
P27A9 (Permanent)
Controller Type ID By OS: 73

None: 7ED, CAN, BSCM-BrakeSystem
Calibration IDs: 84744979, 84561049, 84561079
Calibration VNs: 00007CFF, 00001132, 00009FB0
Basic PIDs: 3

None: 7EE, CAN, GPCM-GlowPlugCtrl
Calibration IDs: 12704709, 12688412
Calibration VNs: 00009C94, 00004BC1
Basic PIDs: 6

Post your file so we can help.

But it sounds like you need to flash a file to it so the TCM knows what it?s supposed to do.

Unsure on this because I have only done a few L5P TCM?s

Firstly, the variety of codes, especially U0101 (Lost Communication with TCM) and U0100 (Lost Communication With ECM/PCM A), point towards a communication breakdown between the ECM and the new TCM. This could be due to incorrect installation, a fault in the TCM itself, or potentially incorrect serial/hardware that doesn’t match your truck’s specifications (PCM/ECU)

The engine power reduction and the lit traction control lights, paired with the gear indicator not working and the myriad of transmission-related codes like P0700, which signals a broader transmission control system issue, suggest the new TCM isn’t correctly communicating or operating with the rest of your vehicle’s systems. The specific P27 series codes (P27A7 through P27AD, P27A8, P27A9, and P281B related to pressure control solenoids) imply there’s a deeper issue within the transmission control, possibly linked to how the new TCM is managing pressure control solenoids or interpreting signals from the ECM. The first step should be a thorough check of the TCM installation to ensure it’s properly seated, and all connections are secure and not damaged.