trying to trace a short, help?

[krkkeith]

01 Boxster S used as track only car. Durametric reports a short with these fault codes
Current Fault Codes 34: Passenger compartment monitoring sensor, short circuit to ground Status: present Occurance Counter: 1
16: Voltage failure at terminal 30 with alarm system active Status: present Occurance Counter: 1

This blows 15A fuse C3. It is a dead ground for 20 minutes or so after running car then goes away. Car runs fine even with fuse blown, but windows and lock will not work with blown fuse.

Any thoughts on how to trace this short?