The ABS is now part of the 'start enable' section of the immobiliser on some modern vehicles.

Without the correct responce from the ABS when requested the vehicle remains immobilised.

The ABS can also store the mileage so not a good idea to plug another unit in to test as it could be an expensive mistake!

This is part of the reason why it is difficult to answer alot of the requests for help nowadays on forums as you are always unsure of the testers understanding of the system (TRAINING/RESEARCH)so therefore cannot have any idea how/what they have tested.

Regards
Sean