CAS you dont have to use it if the computer your useing is OBD1 OBD2 computer you would have to use it or it run like shitt,in this case you need to change the oil pump due to your dont have the spot for the sensor to bolt on,and you need a OBD2 computer to pass ...Since you got a OBD1 set up you can throw what I said out the door b/c its not going to read anything threw your DLC so your screwed unless you fix it like I said ... (fix it) change oil pump ,add CAS sensor,plug it in ,change computer, Thanks Joshua