This is the rebuild manual for the new Hydra-matic 8L90 (8 Speed RWD & 4WD). It is a fully automatic eight speed rear wheel drive transmission that is available in both two and four wheel drive configurations. It features clutch to clutch shifting which provides eight forward and one reverse gear.
Covers assembly, dis-assembly, diagnosis, troubleshooting, and electronic controls & operation.
The 8L90 has undergone some parts changes from it’s inception until the present. Some of those changes are indicated in this manual and some are not.