LR3/Disco 3
When the driver selects the Terrain Response rock crawl special program, which is only available with the transfer box in
low range, the TCM uses a specific shift map which maximises torque delivery at slow speeds associated with this type of
terrain.
TRANSMISSION FAULT STATUS
If the TCM detects a fault with the transmission system, it will enter a default mode to prevent further damage to the
transmission and allow the vehicle to be driven.
When a fault is detected a CAN message is sent from the TCM and is received by the instrument cluster. The instrument
cluster illuminates the MIL and displays 'TRANS. FAILSAFE' in the message centre.
Some transmission faults may not illuminate the MIL or display a fault message, but the driver may notice a reduction in
shift quality.
ENGINE SPEED AND TORQUE MONITORING
The ECM constantly supplies the TCM with information on engine speed and torque through messages on the CAN bus.
The TCM uses this information to calculate the correct and appropriate timing of shift changes.
If the messages are not received by the ECM, the TCM will implement a back-up strategy to protect the transmission from
damage and allow the vehicle to be driven.
In the event of an engine speed or torque signal failure, the transmission will adopt the electrical limp home mode with the
transmission operating in a fixed gear.
TOWING FOR RECOVERY
The following procedure must be used to ensure that the vehicle is towed in a safe condition and damage to the vehicle
transmission systems is prevented.
Secure the towing attachment from the recovery vehicle to the towing eye of the vehicle to be recovered.
Make sure that the hand brake is on. Turn the ignition key to the ignition position II.
Apply the footbrake and move the automatic transmission selector lever to the neutral position. If electrical power
is not available, use the manual interlock release tab on the selector lever to move the lever to the neutral
position.
Make sure that the ignition is in the auxiliary position I or, if the stop lamps and turn signal indicators are required,
in the ignition position II.
Make sure that the hand brake is released before the vehicle is towed.
The vehicle can only be towed for a maximum of 31 miles (50 km) at a maximum speed of 30 mph (50 km/h).
Towing the vehicle for longer distances and/or faster speeds will damage the transmission.
CONTROL DIAGRAM
NOTE :
WARNING : Do not remove the key or move the ignition switch to position 'O' when the vehicle is being
towed. The steering lock will be engaged preventing the steering from being turned. With the engine not
running, the brake booster and power steering pump will be inoperative. Care must be taken to ensure the
vehicle is manoeuvred and driven accordingly.
A = Hardwired; D= High Speed CAN Bus
