Try a search for fault code reader, aka Arthur Dalton code reader. You can build the code reader yourself with inexpensive parts from Radio Shack. Here's some more info on 8 pin code reading including the list of faults on CIS pin 3.

http://mywebpages.comcast.net/chwilka/Error_Code%20_reader_reset_tool.htm#Reading%20SRS%20Codes%20(copied%20from%20MBCoupes%20archive,%20e mail%20sent%20by%20Randy%20D.)