Do you know if he is getting power to the data link connector? Pin 16 should have 12v at all times.
If it is, then what needs to be done is the have the CAN scanned for diagnostic codes. CAN stands for controller area network. Basically, all computers/modules are tied together via a few wires. If there is a breakdown in communication via the CAN bus system, that can prevent communication.
Here is a quick video showing how it's done:
I attached the schematic of the CAN system below for you to review. I had to cut the pic in half to make it readable for you, but I did overlap them so you can follow from one to the next.
Take care and let me know if you have other questions.
See pics below.
Images (Click to enlarge)
Tuesday, September 14th, 2021 AT 8:40 PM