This is a VERY comprehensive 185 Page PDF Service Guide covering the OBD2 Diagnostics for The GM 4L60E, 4L65E, 4L70E, 4L80E and 4L85E Transmissions. It contains a great many contributions from the Members of the GM Automatic Transmission Service Group (ATSG) imparting arcane knowledge, tips and tricks offered up by the many Professionals working in this largely mysterious branch of Automotive Repairs; one not usually accessible to most of us. THIS one is definitely a 'Download and KEEP' kind of a Document:
http://shop.ukrtrans.biz/wp-content/uploads/catalogs/4L60E_80E_CODE_BOOK.pdf
http://shop.ukrtrans.biz/wp-content/uploads/catalogs/4L60E_80E_CODE_BOOK.pdf