Under the dash on the drivers side.
The 1996 Mercury Grand Marquis OBD 2 port is on under driver side dash next to center console
I believe the obd port is located by the parking brake and just above it.
The OBD II port connector is located to the left of the steering wheel, just beneath the dash panel.
On a 1993 Mercury Grand Marquis ( which is OBD I , EEC IV ) ( there should be an EEC TEST connection in the engine compartrment )
On my '93, there is no consumer serviceable port. I think the recharge has to be done by a technician.
The OBD connector is under the dash on the driver side.
The OBDII diagnostic port is under the dash to the right of the steering column.
To add Freon to a 2000 Mercury Grand Marquis, locate the low-pressure service port on the AC system, which is typically found near the accumulator or the firewall. Remove the cap from the service port, attach the refrigerant gauge and hose, and then add the appropriate type of refrigerant. Be sure to check the system pressure with the gauge to avoid overcharging. Always follow safety precautions and consult the vehicle's manual for specific instructions.
You must have a code reader to interface with the OBDII data port under the dash.
The 1991 Ford Mustang does not have an OBDII port, because OBDII was not standardized in the United States until 1996.
Not an OBDII, it is ODBI. the conecter is the black "L" shaped connecter near the battery.
OBDII was mandated on all cars by 1996. Some 1994 and 1995 models had an OBDII port, but most (if not all) only provided OBDI information. These were called OBD1.5. I have never seen a 1993 model with an OBDII port.