The CAS (the FSM calls it CMPS) has it's own power lead, coming from the ECU, I'd check that first. I believe it's the white wire that should carry +voltage (test light to that and ground).
Because it's such an important component, it is a level 1 check-engine-light part, so there's not really a lot covered in the FSM about checking it (the FSM says either the MIL is on, and it's the CAS, or it's off and it's not). Here's one thing I did find that you could check:
check injector clicks with a flathead screwdriver on the injector body or get your ear real close. It should be pretty obvious.