Ray, without opening the car, peer inside and see if the light switch module is illuminated with the car locked.
I had to replace the LSM on my own ZT for this exact fault, and it's not uncommon either
If the LSM is defective, it will not allow the BCU to enter "sleep mode" meaning instead of a quiescent current of around 45mA, you will see a 1.5 to 2 amp current draw at all times
An easy and non intrusive test, with no tools required other than a dark night
Brian
