Transmission Description: Introduction

The ZF 6HP28 transmission is an electronically controlled, hydraulically operated, six speed automatic unit. The hydraulic and electronic control elements of the transmission, including the transmission control module (TCM), are incorporated in a single unit located inside the transmission and is known as 'Mechatronic'.

3.0L diesel models use an uprated derivative of the ZF 6HP28 transmission used in the 5.0L naturally aspirated models.

The ZF 6HP28 transmission has the following features:

• Designed to be maintenance free
• Transmission fluid is 'fill for life'
• The torque converter features a controlled slip feature with electronically regulated control of lock-up, creating a smooth transition to the fully locked condition
• Shift programs controlled by the transmission control module (TCM)
• ASIS (adaptive shift strategy), to provide continuous adaptation of shift changes to suit the driving style of the driver, which can vary from sporting to economical
• Connected to the engine control module (ECM) via the high speed controller area network (CAN) bus for communications
• Default mode if major faults occur
• Diagnostics available from the transmission control module (TCM) via the high speed controller area network (CAN) bus.

The transmission selections are made using the selector lever in the floor console and two paddle switches on the steering wheel. Refer to External Controls article.