The Z8's first task is to initialize its' I/O pins. That done, it goes on to determine the presence or absence of the HC-05 module, as I would like to have radio-silence available as an option. Even though the module is present, for some reason, it is not being detected.

Shall I skip over the trials and tribulations of coaxing the updated module in to operation?

Sure, because in the end, the difference was mostly how the reset and "key" pins operated.

The module also handles paired devices a little differently, allowing me to remove the bit of code that facilitated un-pairing a device.

Now having a working bluetooth interface, it's time to put the device in front of the pump monitoring device.