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Range Rover. Manual - part 154

ZF AUTO

DESCRIPTION AND OPERATION

EAT ECU connector - Petrol vehicles from 99MY

EAT ECU connector pin details - Petrol vehicles from 99MY

Pin No.

Description

Input/Output

1 to 4

Not used

Pressure regulator solenoid valve (MV 4)

Output

Power earth

Not used

Gear position switch, Y contacts

Input

9 to 12

Not used

Transmission high/low switch

Input

Gearbox output shaft speed sensor, negative

Input

Gearbox output shaft speed sensor, cable screen

CAN high

Input/Output

17 to 24

Not used

MES 1 - message centre display

Output

Battery supply

Input

Not used

Electronics earth

Not used

Shift control solenoid valve (MV 1)

Output

AUTOMATIC GEARBOX

NEW RANGE ROVER

DESCRIPTION AND OPERATION

EAT ECU connector pin details - From 99MY (continued)

Pin No.

Description

Input/Output

Diagnostics, K line

Input/Output

Converter lock-up solenoid valve (MV 3)

Output

Shift control solenoid valve (MV 2)

Output

34/35

Not used

Gear position switch, X contacts

Input

Gear position switch, Z contacts

Input

38 to 41

Not used

Gearbox output shaft speed sensor, positive

Input

Not used

CAN low

Input/Output

Mode switch

Input

46 to 50

Not used

MES 2 - message centre display

Output

Not used

Solenoid valves power supply

Output

Ignition power supply

Input

55 to 75

Not used

ZF AUTO

DESCRIPTION AND OPERATION

OPERATION

General

The gear position switch outputs are monitored by the
BeCM and the EAT ECU. The BeCM outputs gear
position signals to illuminate the position indicators
each side of the gear selector lever and on the
message centre in the instrument pack.

In D, 3, 2, and 1, the EAT ECU outputs control signals
to the gearbox to select the required gear.

In D, all forward gears are available for selection by
the EAT ECU. In 3, 2 and 1, a corresponding limit is
imposed on the highest gear available for selection.
When R is selected, reverse gear only engages if the
vehicle is stationary or moving at 5 mph (8 km/h) or
less.

Selector Lever Interlock (where fitted)

The interlock solenoid on the selector lever is
de-energised unless the foot brake is applied while
the ignition is on. While de-energised, the interlock
solenoid allows the selector lever to move through the
range unless P is selected.

On entering the P position, the interlock solenoid
engages a latch which locks the selector lever. When
the ignition is on and the foot brake is applied, the
BeCM energises the interlock solenoid, which
disengages the latch and allows the selector lever to
be moved out of P.

Economy, Sport and Manual Modes

During the power-up procedure after the ignition is
switched on, the EAT ECU defaults to an economy
mode. Pressing the mode switch causes the EAT
ECU to change between the economy mode and the
sport or the manual mode, depending on the range
selected on the transfer box:

•

If the transfer box is in high range, the EAT ECU
changes to the sport mode and illuminates the
sport mode lamp on the selector cover and
displays ’S’ in the instrument pack message
centre. In the sport mode the gearbox is more
responsive to accelerator pedal movement.
Downshifts occur earlier and upshifts occur later.

•

If the transfer box is in low range, the EAT ECU
changes to the manual mode and illuminates the
manual mode lamp on the selector cover and
displays ’LM’ in the instrument pack message
centre. Kickdown is disabled and the EAT ECU
maintains the gearbox in the gear selected on
the selector lever (D = 4th gear) to give
improved off road performance. Downshifts
occur only to prevent the engine stalling.

From a standing start, the vehicle pulls away in
1st gear and, if a higher gear is selected,
upshifts almost immediately to the selected gear
(shifts of more than one gear can occur).

•

After a second press of the mode switch the EAT
ECU reverts to the economy mode, for the range
selected on the transfer box, and extinguishes
the related mode lamp on the selector cover and
removes the ’S’ or ’LM’ display in the instrument
pack message centre.

•

When the vehicle is in the default mode (i.e. high
range and economy) and towing or driving up
steep gradients, the EAT ECU will select a shift
pattern appropriate to the driving conditions. If a
heavy trailer is being towed or a steep gradient
is encountered, the transmission will hold in the
gears longer than in normal operation.

Shift Control

To provide the different driving characteristics for each
mode of operation, the EAT ECU incorporates
different shift maps of throttle position/road speed.
Base shift points are derived from the appropriate shift
map. When a shift is required, the EAT ECU sends a
request to the ECM for a reduction in engine torque, in
order to produce a smoother shift. The percentage of
torque reduction requested varies according to the
operating conditions at the time of the request.

AUTOMATIC GEARBOX

NEW RANGE ROVER

DESCRIPTION AND OPERATION

When the EAT ECU receives confirmation of the
torque reduction from the ECM, it then signals the
shift solenoid valves in the gearbox to produce the
shift. To further improve shift quality, the EAT ECU
also signals the pressure regulating solenoid valve to
modulate the hydraulic pressure and so control the
rate of engagement and disengagement of the brake
clutches.

With time, the components in a gearbox wear and the
duration of the gear shifts tends to increase, which
has an adverse affect on the brake clutches. To
counteract this, the EAT ECU applies a pressure
adaptation to each shift. To calculate the adaptations,
the EAT ECU monitors the pressure modulation used,
and time taken, for each shift. If a subsequent shift of
the same type, in terms of throttle position and engine
speed, has a longer duration, the EAT ECU stores an
adaptation for that type of shift in a volatile memory.
The adaptation is then included in future pressure
calculations for that type of shift, to restore shift
duration to the nominal.

Kickdown

The EAT ECU monitors the input of the throttle
position sensor to determine when kickdown is
required and select a gear to give the best available
acceleration. When it detects a kickdown situation, the
EAT ECU immediately initiates a down shift of one or
two gears or will maintain the current gear to avoid
engine overspeed.

Torque Converter Lock-Up

The EAT ECU energises the lock-up solenoid valve to
engage the lock-up clutch. Lock-up clutch operation is
dependent on throttle position, engine speed,
operating mode and the range selected on the
transfer box.

High Range

Unique lock-up maps, similar to the shift maps, are
incorporated in the economy and sport modes for all
forward gears. Engagement and disengagement of
the lock-up clutch is dependent on throttle position
and engine speed.

Low Range

To enhance off road control, particularly when
manoeuvring at low speeds, torque converter lock-up
does not occur when there is any degree of throttle
opening. When the throttle is closed above a preset
engine speed, the lock-up clutch engages to provide
maximum engine braking.

Increased Load/Reduced Torque Compensation

To aid performance and driveability in the high range
economy mode, the EAT ECU has three adaptive shift
and lock-up maps. These maps delay upshifts and
torque converter lock-up similar to the sport mode if
the inputs from the engine indicate:

•

A sustained high load on the engine, such as
occurs when the vehicle is ascending a steep
gradient or towing a trailer.

•

The EAT ECU monitors the engine inputs and
selects the most appropriate adaptive map for
the prevailing conditions.

•

On vehicles from 99MY, a lower than normal
engine torque, such as occurs at altitude or high
ambient temperatures.

Diagnostics

While the ignition is on, the EAT ECU diagnoses the
system for faults. The extent of the diagnostic
capability at any particular time depends on the
prevailing operating conditions, e.g. it is not possible
to check torque converter lock-up while the vehicle is
stationary, or to check for a short circuit to earth if the
circuit concerned is already at a low potential.

If a fault is detected, the EAT ECU immediately stores
a fault code and the values of three operating
parameters associated with the fault. Depending on
the fault, there are four possible effects:

•

The fault has little effect on gearbox operation or
vehicle emissions. The driver will probably not
notice any change and the warning lamps
remain extinguished.

•

All gears are available but kickdown does not
function. ’GEARBOX FAULT’ will be displayed
on the instrument pack message centre. The
MIL remains extinguished.

•

Limp home mode is selected and vehicle
performance is greatly reduced. ’GEARBOX
FAULT’ will be displayed on the instrument pack
message centre. If the fault is detected on a
second consecutive drive cycle, the MIL
illuminates.

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