Just a quick question here,
Is the park assist the sound only version (I.E. there is no display on the centre colour LCD screen, the system just beeps at you),
or is it the full beans with the centre screen display and sound ?
If its the sound only version, the module wont be connected on the bus.
(Its just a stand alone device that is connected to the reverse light power feed, and the rear sensors, and turns on when reverse is selected.
(They can have override switches if you have the factory towpack fitted).
It may be a simple case of the speaker being blown, the module has been accidentally switched off, no power going to the unit, or the unit is faulty.
(Luckily these units are easily diagnosed).
If you have the full beans version like what is fitted to Calais V models, then these are connected to the SW Can, so they have the ability to throw DTCs.
Im having trouble with mine, but thanks to RICeY, and some excellent suggestions regarding the modules commonly dying, I am pretty sure in my case the module has died.
(I have replaced my module with one from a wrecked senator, and before park assist was intermittently working when it was cold, now it is not working at all).
Which kinda suggests that I either have another dud module, or the module needs to be programmed for my car.
The Intermittently working bit with my old module is definitely temperature related, so I have the module out, and I am going to try and reflow solder the b@$t@rd and see if I can get it to work again.
Hopefully some of this information may help you, or others that may face the same problem.
Cheers