Land Rover Range Rover Automatic Transmission System Rover Manual

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© Rover Group 1998Page 5 of 52 2.2 Interface specification
2.2.1 Gear Shift Solenoids
2.2.1.1 Pin 5 - Pressure regulator
The purpose of the Pressure regulator is to generate modulation pressure for the gearbox clutches.  The
pressure regulator is mounted between the common output supply (pin 53) and pin 6.  It is driven by a
pulse width modulated power signal that is generated and regulated in the CG202 ASIC.
+
The pulse width modulated signal frequency f
0 is generated permanently; the free running duty cycle
corresponds to the minimal current and the maximal modulation pressure
- Component
- Type2/2-way relief jet with falling characteristic line; the control edge 
is closed when the valve is without power supply.
- Coil resistance R5.5W +/- 6% @20°C
- I_max700mA mean value
- I_min150mA mean value
- Chopper frequency1000Hz +/- 50Hz @ +25°C
- Control Unit
- Interface characteristiccurrent regulated, chopped output stage, pulse width modulated.
- Current range145mA 
						

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© Rover Group 1998Page 6 of 52 - Control unit
- Interface characteristicPower output
- Output voltage lowU_sat 
						

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© Rover Group 1998Page 7 of 52 If the battery supply is different from that expected, the following details the functionality of the
transmission controller:
VoltageSystem behaviour
16.0-26.0Jump start; excess voltage without damage, limphome mode, output stanges for
solenoid valves and pressure regulator switched off (max 1min at 40°C).
9.0-16.0Voltage range for normal operation of the EAT with CAN-Bus corresponding to the
specification.
6.5-9.0Operation of the EAT with diagnostic functions and CAN-Bus enabled, limp home
mode, output stages for solenoid valves and pressure regulator switched off.
3.0-6.5Under voltage with data retention in SRAM, limp home mode, unreliable
communication over the CAN bus.
0-3.0Undervoltage without reliable function
-14-0
Reversed polarity without damage (-14V max 1 min at 25°C)
- Recommended wire size:1.5mm2
2.2.3 Serial information - inputs
2.2.3.1 Pins 16 and 44 - CAN information from Engnine management system
Both Discovery Series II and 99MY Range Rover vehicles use a CAN specification owned by ZF called
CAN 22H.  This communication protocol operates at 500kBit/sec. Both the engine management system
and the transmission controller should be fitted with 120W terminating resistors.  For more information
on the CAN bus, please refer to the CAN specification.
2.2.4 Serial information – outputs
2.2.4.1 Pins 16 and 44 - CAN information sent to Engine Management system
See section the relevant section - CAN information from the Engine management system.
2.2.5 Digital inputs
2.2.5.1 Pins 8, 9, 36, 37 - Position switch
The position switch is the electrical input to the Transmission ECU regarding the drivers requested gear.
It is not however, exactly the same as the gear which the Transmission may have selected.  The
transmission assumes a new selector position has been selected after it has recognised a stable input /
code from the position switch lines for a filter time TPO_FILT. 
						

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© Rover Group 1998Page 8 of 52 Discovery Series II (GS8.87.0):
A 12V supply is required to the position switch whenever there is an ignition feed to the Transmission
controller.  If this is not realised, the transmission will be unable to function correctly and so limphome
mode will permanently be selected.  The movement of the gear lever will make or break with 4 different
sliding contacts.  This creates a coded representation of the selected gear.  These 4 wires go directly to
the Transmission ECU (Terminals L1, L2, L3 and L4) where they are decoded.  The software will then
decide if the selected gear can be safely engaged without damage to the Transmission and Engine.
- Component
- TypeMake contact to +12V
- LocationGearbox, assembled together with the switch block
- PositionsMechanicalP R N D 3 2 1
HydraulicP R N D 1
ElectricalP R N D 3 2 1 Z
- Control Unit
- Interface characteristicDigital input, acitve high
- Threshold U_low to U_high=2.0V, label U_US_AD
- HysteresisU_low to U_high >= U_high to U_low + 0.5V
- Input circuit(1.15 +/- 0.2) kW (pull down to Ground)
- Input current12.2 mA; input shorted to U_batt = 14V, R_in = 1.15 kW
- Reference pointU_batt, pin 54
- Coded position inputs (a 1 represents a high potential, pulled high by the position switch)
Position
SwitchECU
PinPZ1RZ1NZ2DZ33Z42Z41Line 1 (W)361101111100000Line 2 (X)80111100110000Line 3 (Y)370000111111011Line 4 (Z)90000001111110 
						

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© Rover Group 1998Page 9 of 52 99MY Range Rover (GS8.87.1):
The position switch feed must be attached to ground at all times.  If this is not realised, the transmission
will be unable to function correctly and so limphome mode will permanently be selected.  The movement
of the gear lever will make or break with 3 different sliding contacts.  This creates a coded representation
of the selected gear.  These 4 wires go directly to the Transmission ECU (Terminals L1, L2 and L3)
where they are decoded.  The software will then decide if the selected gear can be safely engaged without
damage to the Transmission and Engine.
- Component
- TypeMake contact to Ground
- LocationGearbox, assembled together with the switch block
- PositionsMechanicalP R N D 3 2 1
HydraulicP R N D 1
ElectricalP R N D 3 2 1 F
- Control Unit
- Interface characteristicDigital input, acitve low
- Threshold U_low to U_high=2.0V, label U_US_AD
- HysteresisU_low to U_high >= U_high to U_low + 0.5V
- Input circuit(1.21 +/- 0.2) kW (pull up to U_batt)
- Input current-11.2 mA; input shorted to Ground, R_in = 1.21 kW
- Reference pointDigital ground, pin 28
- Coded position inputs (a 0 represents a low potential, pulled low by the position switch)
Position
SwitchECU
PinPRND321Line 1 (W)360011000Line 2 (X)81000011Line 3 (Y)371110001 
						

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© Rover Group 1998Page 10 of 52 2.2.5.2 Pin 13 - High / Low range input
Discovery Series II (GS8.87.0):
The high / low range switch is electrically connected both to the transfer box and the EAT.  It sets the
transmission ratio of the transfer box and indicates the selected range to the EAT.
The closed switch indicates Low range, and open switch indicates high range.  After a change of the
signal (a rising or falling edge), the EAT ratains the signal vaue before the change for the applicable time
THL_WAIT.
- Component
- TypeMake contact to ground
- LocationCentre console
- Switch openHigh range
- Switch closed (to ground)Low range
- Control Unit
- Interface characteristicDigital input, active low
- Threshold U_low to U_high=< 6.0V, U_OS_AD
- Threshold U_high to U_low=> 2.0V, U_US_AD
- HysteresisU_low to U_high => U_high to U_low +0.5V
- Input circuit(1.2 +/- 0.2) kW (pull up to Ubp)
- Input current-10mA, input grounded, U_batt = 14V, R_in = 1.2kW
- ReferenceDigital ground, pin 28 
						

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© Rover Group 1998Page 11 of 52 99MY Range Rover (GS8.87.1):
The high / low range switch on 99My Range Rover is a component of the H-gate.  It is electrically
connected to the transfer box; the input signal to the EAT is generated in the control unit of the transfer
box.
A constant high signal indicates Low range, a constant low signal indicates high range.  When the range
is changing from Low range to High range, the transfer box ECU sends a periodic pulse whilst in the
neutral position.
After a change of the signal (ie a rising or falling edge), the EAT retains the signal value before the
change for the applicable time THL_WAIT.
- Component
- TypeActive low
- LocationTransfer box
- Signal open circuit / highLow range
- Signal active / lowHigh range
- Control Unit
- Interface characteristicDigital input, active low
- Threshold U_low to U_high=< 6.0V, U_OS_AD
- Threshold U_high to U_low=> 2.0V, U_US_AD
- HysteresisU_low to U_high => U_high to U_low +0.5V
- Input circuit(1.2 +/- 0.2) kW (pull up to Ubp)
- Input current-10mA, input grounded, U_batt = 14V, R_in = 1.2kW
- ReferenceDigital ground, pin 28 
						

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© Rover Group 1998Page 12 of 52 2.2.5.3 Pin 45 - Driver mode request
Discovery Series II (GS8.87.0):
The program selector is used to select shift strategies depending on the setting of the High/Low range
switch.  The strategies can be selected independently for High range and Low range.  After ignition on
and after changing between High range and Low range, the EAT assumes a default shift strategy (normal
mode).
The number of implemented shift strategies can be individually set for High range and Low range by the
label KPG_MAX
The program selector is a push button that is debounced and latched by software in the EAT.  The EAT
changes the shift strategy after it has recognised the stable input voltage U_low for the time period
TPG_FILT
- Component
- TypeMake contact to ground
- Max bounce time 2.0V, U_US_AD
- HysteresisU_low to U_high => U_high to U_low +0.5V
- Input circuit(1.2 +/- 0.2) kW (pull up to Ubp)
- Input current-10mA, input grounded, U_batt = 14V, R_in = 1.2kW
- ReferenceDigital ground, pin 28
99MY Range Rover (GS8.87.1):
The purpose of the program selector is to select shift strategies depending on the setting of the High /
Low range input.  The strategies can be selected independantly for High Range and Low Range.  After
ignition on and after changing between high range and low range, the EAT assumes a default shift
strategy (normal mode).
The number of implemented shift strategies can be inndividually set for high range and Low range by the
label KPG_MAX.
The program selector is a switch that is debounced and latch internally.  The EAT changes shift strategy
after it has recognised a stable input voltage for a time period TPG_FILT. 
						

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© Rover Group 1998Page 13 of 52 - Component
- TypeMake contact to ground
- Max bounce time 2.0V, U_US_AD
- HysteresisU_low to U_high => U_high to U_low +0.5V
- Input circuit(1.2 +/- 0.2) kW (pull up to Ubp)
- Input current-10mA, input grounded, U_batt = 14V, R_in = 1.2kW
- ReferenceDigital ground, pin 28
2.2.6 Digital outputs
2.2.6.1 Pin 25 and 51 - MES lines 1 and 2
The MES signal lines drive lights in the instrument pack that display the selected shift strategy and the
EAT’s fault state.  Pin 51 and Pin 25 are open drain outputs.  The following table shows the switching
function; a “0” represents a low output, a “1” represents a high output voltage.
MES 1 - Pin 51MES 2 - Pin 25Normal11Sport01Manual10Fault00- Component
- U_lowU < 1.2V
- U_highU > U_batt - 3.0V
- R to U_batt1.0kW
- Control unit
- Interface characterisicsDigital output / open drain, active low
- U_low= U_batt - 2.0V at I 
						

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© Rover Group 1998Page 14 of 52 2.2.7 Analogue inputs
2.2.7.1 Pins 14,15,42 - Output shaft speed sensor
The transmission output shaft speed is captured by an inductive sensor that is mounted at a magent wheel
with 36 teeth.  The signal is transmitted to the EAT over a shielded 2-wire connection.
- Component (inductive sensor)
- locationGearbox housing
- output36 pulses per revolution
- f_min102Hz (170 rpm)
- f_max5.0kHz (8333 rpm)
- sensor voltage Ui_min0.7 Vs at 102Hz (peak voltage)
- sensor voltage Ui_max1.3 Vs at 102Hz (peak voltage)
- sensor distance0.85mm
- load resistanceR_1 = 20kW
- Control unit
- Interface characteristicFrequency input
- R_in Pin 14 to Pin 4220kW
- sensitivity U_min1.2Vss (peak to peak) @  100 Hz
- sensitivity U_max200 Vss @ 100 Hz
- f_max6.0 kHz
- Rotational limit
- n_min170 rpm
- n_max8333 rpm
- Switching voltage of input(U @ Pin 42 - U @ Pin 14) /2
- Signal processing in the EAT
- The EAT calculates the mean period time over one program loop.