General Description

GENERAL DESCRIPTION

The AW4 electronic transmission is a conventional transmission in that it uses hydraulically applied clutches to shift a planetary gear train. However, the electronic control system replaces many of the mechanical and hydraulic components used in conventional transmission valve bodies.

The AW4 transmission control system has improved significantly since it's introduction. The Park/Neutral switch was replaced by a Transmission Range Sensor (TRS). The Transmission Control Module (TCM) now has the ability to communicate with the Powertrain Control Module (PCM) via the CCD Bus. The TCM also has the ability to monitor transmission faults which could affect emissions. Any transmission fault which will adversely affect emissions will set a DTC in the PCM and will also illuminate the MIL.

An Input Speed Sensor (ISS) was added to the control system. This gives improved functional trouble detection. This results in a new Diagnostic Trouble Code (DTC) to detect ISS malfunctions. The "Solenoid A or TCC Solenoid Functional Fault" DTC was separated into two DTC's "Shift solenoid A functional fault" and "TCC solenoid C functional fault" and there was also a new DTC for internal TCM failures.