2004 L322 no EGS from Automatic transmission

Hi guys hope y’all doing well , new member here and I need some advice on my 2004 Range Rover vogue L322 TD6 engine. So I bought the car from a friend who packed it for 3 years, started with the suspension and done and then had to change the AC evaporator so I stripped the dash and after installing everything my transmission went into limp mode with a code
No EGS message received from Automatic transmission. The car starts and run but no gear change, I have checked all fuses and connections but couldn’t find the culprit. To my understanding the transmission ECU is out of the CAN network but the engine ECU is and in the wiring the TCM CAN wires passes through the Engine ECU so why is the engine on the CAN but TCM not? Any advice will be very much appreciated

Ok so found the problem
The TCM was dead but somehow was signaling the car to start
Changed it and problem solved

Sorted, à bit light on the replies