I have a reasonable, though not ideal, solution for getting the rear hatch locked. The lock system rocker switch (on the console) behaves as follows on my car:
- Only locks when the ignition switch is in Accessory or Run position. (I believe it's supposed to work in any ignition switch state).
- Only locks when driver's door is closed.
- When system is locked by the console rocker switch, both doors and rear hatch lock. (I believe the fuel hatch is supposed to lock, but mine does not).
- Opening the driver's door activates unlocking of everything.
- The result is that I can only lock the doors manually with the passenger door lock plunger and driver door key lock. The car cannot be left with the rear hatch locked.
I figured that the rear hatch should stay locked if the system "thinks" the driver's door is closed. Some fiddling around revealed that the unlocking is dependent on the door position switch, conveniently located in the door jamb just above the latch striker. It's easy to access by removing the door seal and peeling back the sidewall carpet, then pushing the switch out from the inside. Just pulling the connector works, but I didn't want a loose connector, so I removed the spring from inside the switch so the plunger stays retracted.
Now I can stop, hit the console switch, *then* turn off the ignition, and everything is locked. The driver's door handle will mechanically unlock the door, which I can re-lock from the outside with the key. I doubt I'll be able to lock the fuel door without restoring normal operation to the whole system, which is doubtful.
Not great, but at least the car can be secured now.