Land Rover Discovery: Automatic Transmission Transaxle / Description and operation
COMPONENT LOCATION
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- Paddle switches - upshift / downshift
- Transmission Control Switch (TCS)
- Transmission Control Module (TCM)
- ZF 9HP48 Automatic transmission
- Automatic Transmission Fluid (ATF) cooler with integrated thermostat
OVERVIEW
The ZF 9HP48 automatic transmission is a 9 speed, electronically controlled unit manufactured by ZF. The transmission represents the latest in automatic transmission technology for a transverse, AWD (all-wheel drive) unit. The transmission features lock-up slip control, 'CommandShift' functions and automatic and driver selectable modes to give the optimum on and off road performance.
The automatic transmission is controlled by a TCM (transmission control module) which contains software to provide operation as a semi-automatic 'CommandShift' transmission. Driver selections for P, R, N, D and S on the rotary TCS (transmission control switch) are received by the TCM. The TCM operates solenoid valves and clutches to control transmission gear shifts, allowing the system to operate as a 'shift by wire' system, with no mechanical link to the transmission for drive selections.
The TCM allows the transmission to be operated as a conventional automatic unit by selecting P, R, N, D, S on the TCS. Rotation of the TCS to the 'S' position puts the transmission into electronic 'Sport' mode.
Operation of the steering wheel mounted + or - paddle switches puts the transmission into electronic manual 'CommandShift' mode.
For additional information, refer to: External Controls (307-05 Automatic Transmission/Transaxle External Controls, Description and Operation).
The ZF 9HP48 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 lock-up control on gears 1 to 9
- Planetary gearset with 9 speeds, 4 planetary geartrains, and 6 shift elements
- Wide transmission ratio spread with small ratio steps
- The first-ever use of interlocking dog clutches in a passenger car automatic transmission
- Shift programs controlled by the TCM
- TCM has an adaptive capability to ensure efficient gear shift quality throughout the service life of the transmission
- Diagnostics available from the TCM via the high speed CAN (controller area network) Powertrain systems bus.
- Automatic Transmission Transaxle / Component Description
- Valve Block
- Drive Clutches
- Planetary Gear Trains
- Park Lock
- Instrument Cluster
- Transmission Fault Status
- Engine Speed and Torque Monitoring
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Automatic Transmission Transaxle
/ Component Description
The transmission comprises the main casing which houses all of the
transmission components. The torque converter is located in a separate
converter housing, bolted to the main casing.
ZF 9HP48 Cut-Awa
Valve Block
The valve block is located in a vertical position at the front of the
transmission main casing, behind a sealed cover. The valve block contains a
number of solenoids and spool valves to control the t
Drive Clutches
Multiplate Drive or Brake Clutch - Typical
Cylinder
Piston
Disk spring
Metal plates
Friction plates
Baffle plate
Pressure equalization chamber
Piston chamber
There are two multiplate drive
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Parking Exit
Parking Exit Sequence
When parking exit is selected, the park assist sensors search the area for a
space that is big enough to manoeuver out off.
When a space big enough has been identified, the park assist sensors
inform the Parking Aid Control Module (PACM) so that the PACM control
calculate
Front Row Seat
Backrest Blower (G1780403)
/ Removal and Installation
REMOVAL
NOTES:
Some variation in the illustrations may occur, but the essential
information is always correct.
Removal steps in this procedure may contain installation details.
Refer to: Front Seat - Vehicles With: Power Seats (501-10, Removal
and Installation).
INSTALLATION
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