Quote Originally Posted by Y33TREKker View Post
Have you seen any info indicating whether aftermarket readers can be used for obtaining the codes?
Never tried to search for that. I know the TechII is rather good. My local GM (Isuzu agent in SA) agent uses it. I've got a good relationship with him. He doesn't mind just quickly plugging in and having a look.

Neg terminal off for 30 seconds works for me for Check Engine, and pin 8 work well for TOD error codes. Of course terminal off don't give you any codes....but it does get rid of the odd intermittent problem.