355The Candi Module should not plugged into your Tech 2 Scan Tool 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.
Boot screen not showing CANdi present, diagnostics for CANdi says it isn’t seen.
Here I connected OBD I adapter to end of CANdi cable:
OBD I adapter connected.