The Candi Module should not plugged into your GM Tech 2 unless you’re working on a later car ..generally 2005 plus. Olders car from 96 should NOT have the Candi Module attached. OBD I only has 1 ground, so 12 pin adapter connects signal and chassis ground to the Tech 2 cable. OBD II has chassis and signal ground and they are connected in the cars wiring. How I was trying to get GM TECH2 CANdi module to work: Nothing on CANdi end of cable. ...