1) is the OBD (self test)part of the ECM unit or is it a totally different unit
2) if i go to auto zone to get (forget what its called) the scanning tool or the diagnostic trouble code reader,will that show me the failures that accure during my OBD self test?
the reason why i am asking is because i was told that you could have failures during the OBDself test and they wont trigger any codes to show or make the check engine light come on or blink.......thanks for any help would appreciate it

 

If you have OBD2, (1996 or later model year), the OBD connector is wired right into the ECU (ECM). It is a two-way serial digital interface. Sometimes the ECU will not communicate with the OBD, assuming it's not a broken wire or something the only cure is replacing the ECU. This is very rare.

You can take your car to autozone and they'll hook up a scan tool and do a scan for free without you having to buy one.

 

thanks for the response i foud out what the problem was ......i guess when i bought the car the previous owner took the RADIO/ BACKUP fuse out of the under hood fuses compartment and that was reseting my ecm constantly