Planetary Gear Trains

The 8 forward gears and the reverse gear are produced by a combination of 4 simple planetary gear sets, 3 clutches, 1 brake and a launch clutch. The front 2 gear sets share a common sun gear. Power is output always through the planetary carrier of the fourth gearset.

The 5 shift elements comprising 3 clutches, 1 brake and a launch clutch, are responsible for all 8 forward and reverse gears. High efficiency is achieved by the use of only 2 shift elements disengaged in each gear which reduces drag.

Over Temperature Messages 

The transmission clutch temperatures are modelled within the TCM  . The 8P75XPH transmission incorporates additional monitoring of the B clutch as this is worked hard on low speed crawl situations. The TCM  uses algorithms to detect high load on the launch clutch and when detected provides a message to the driver to select low range. Further monitoring then provides a critical warning to the driver with a notification sound from the instrument cluster to select low range. The critical warning occurs if this first message is ignored.