Introduction

Introduction

The electronic automatic transmission is similar to that of a conventional hydraulic automatic transmission. However, in a conventional automatic transmission there are no electronics and the gear shifting is achieved via a hydraulic valve block. This means the transmission calibration is a compromise to give acceptable gear changes wherever possible.

In an electronic automatic transmission, the hydraulic valve block is replaced with an electronically controlled hydraulic valve block. This allows the shift points and valve pressures to be calibrated individually for every possible situation. The result is an improvement in shift quality.

The electronic control module is programmed with software which monitors all the relevant electrical inputs required to decide what type of shift should be made. As well as this information, several strategies exist within the software to improve the driveability and functionality of the vehicle.

Diagnostic Trouble Codes (DTCs) and Freeze Frames (FRZF)

In the event that a fault occurs which results in a noticeable deterioration of vehicle functionality, the driver will be informed by a message in Message Centre and by an audible beep. If the vehicle is a North American Specification (NAS) and the fault will cause an increase of emissions of >15%, then the Malfunction Indicator Lamp (MIL) will also be illuminated after the fault has occurred on two consecutive faulty driving cycles.