Transmission Description (G2257834): Overview
The ZF 8HP45 transmission is an electronically controlled, hydraulically operated, eight 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'.
The ZF 8HP45 transmission has the following features:
- Designed to be maintenance free.
- Automatic Transmission Fluid (ATF) 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).
- Adaptive Shift Strategy (ASIS), 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 ECM (Engine Control Module) via the HS (High Speed) CAN (Controller Area Network) Powertrain bus for communications
- Default mode if major faults occur
- Diagnostics available from the TCM via the HS CAN Powertrain bus
- Reduced weight
- Optimized to engine torque.
The transmission selections are made using the Transmission Control Switch (TCS) in the floor console. For additional information, refer to: EXTERNAL CONTROLS
On vehicles featured with Start/Stop system, the 8HP45 Automatic Transmission is fitted with a HIS (Hydraulic Impulse Storage) device to ensure ATF is available to the shift elements as quickly as possible when the engine is started.