5.9 "liftgate ajar" intermittent electrical issue
Recently my 5.9 is getting a "liftgate ajar" indication when the liftgate (rear hatch) is closed. This is a pain in the neck because:
a) I can't leave the doors locked or the alarm horn will sound (even though it's disarmed...but that's another subject)
b) The interior lights are on or flashing on/off at a random rate (extremely annoying and dangerous at night). When leaving the vehicle, I have to disconnect the battery so it doesn't drain.
I have the wiring diagrams, and it implies that there is a short to ground somewhere in the circuit. The diagram also shows that the "liftgate" switch is in parallel with the "liftglass" switch, so it could be either circuit.
Any suggestions where to begin before I start troubleshooting? Any particular components with a history of failure?