Tech2-ing to a part without rest of car.. possible?

[gazz292]

My trailer interface module is playing up a little, some times it detects the plug insterted and will do the bulb out warning on the dash, sometimes it dosent detect the plug is insterted, 

i've 100% checked the switch in the socket is working, zero ohms when the plug is in, perfect connection when it's out (so the switch is open when plug is inserted) 

i can't talk to the TIM with the tech 2 as it says hardware mismatch or no software available... this is because my chassis number isnt one that should have a tow bar, if i try with the vin the TIM has, it still says hardware mismatch, so it must be reading a module elsewhere in the car and getting my vin from it?

so....  the TIM is on the GM-LAN, shares the data wire with the parking sensors, 
would i be able to talk to the TIM if i disconnected it's data wire and connected it directly into the Tech2's pin 1 of the diagnostic connector, with pin 4 or 5 for signal earth,   and of course power to the Tech2.. prolly via the mains adapter. 

Or do these modules need the BCM present to initiate comms? 

if so, could i change the vin in the BCM to match the TIM's one, just to do a variant set up on it, then change it back, or will i set all sorts or things off like theft protections etc? 

I notice my op-com has a button to change the TIM's vin, i tried that, it changes it to mine, but it still says hardware mismatch on the Tech2,