L322 Range Rover System Description and Operation
AUTOMATIC TRANSMISSION – ZF 5HP24
DESCRIPTION AND OPERATION 44-2-49
Operation
Driving Modes
There are a number of different driving modes of operation. Some can be selected by the driver and some are
automatically initiated by the EAT ECU during driving:
l
Normal mode
l
Sport mode
l
Manual (Steptronic) mode
l
Engine warm up mode
l
Hill Descent Control (HDC) mode
l
Cruise mode
l
Hill mode
l
Default (Limp home) mode
l
Reverse lock-out mode
l
Cooling strategy.
Normal Mode
Normal mode is automatically selected by the EAT ECU on power up. In this mode all automatic and adaptive modes
are active. Normal mode uses gear shift and lock-up maps to allow vehicle operation which is a compromise between
performance, fuel consumption and emissions. If the transmission is operated in sport or manual mode and the
selector lever is moved to the 'D' position, normal mode is automatically resumed.
Sport Mode
The sport mode operates in high range only and provides enhanced acceleration and responsiveness. In sport mode
the EAT ECU uses shift maps which allow the transmission to downshift more readily, hold gears for longer at higher
engine speeds, and limits the transmission to 4th gear.
Sport mode is selected by moving the selector lever to the left into the 'M/S' position. When the sport mode is first
selected, 'SPORT' is displayed in the message centre for 6 seconds and, if 5th gear is currently engaged, the EAT
ECU downshifts to 4th.
Manual (Steptronic) Mode
Manual mode allows the transmission to operate as a semi-automatic 'Steptronic' unit. The driver can change up and
down the five forward gears with the freedom of a manual transmission.
Shift maps are provided for manual mode to protect the engine at high engine speeds. The EAT ECU will automatically
change up to a higher gear ratio to prevent engine overspeed and change down to a lower gear ratio to avoid engine
labouring and stalling.
When kickdown is requested the EAT ECU downshifts at least 2 gears.
When the vehicle is stationary, to drive off the driver can select 1st gear in high range, or 1st, 2nd or 3rd gear in low
range. Any other gear selection will be rejected by the EAT ECU.
When driving off, upshifts can be pre-selected by making + selections with the selector lever for the number of upshifts
required. The EAT ECU then automatically performs a corresponding number of upshifts when the appropriate shift
points are reached. So, for example, when starting off in 1st gear, if three + selections are made in quick succession,
the EAT ECU will automatically change up through the box to 4th gear as the vehicle accelerates, without any further
selections being made.
In manual mode a low gear can be selected to provide engine braking for descending a slope without HDC or
continuous use of the brake pedal. The driver can prepare for the end of the descent by moving the selector lever to
D. The EAT ECU will maintain the low gear and only revert to automatic shift control when the throttle is opened and
vehicle speed increases.