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AUTOMATIC TRANSMISSION 5A-3
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N - Neutral allows the engine to be started and oper-
ated while driving the vehicle. The inhibitor switch
allows the engine to be started. There is no power
transferred through the transmission in Neutral. But
the final drive is not locked by the parking pawl, so
thewheels are free to rotate.
D - Overdrive range is used for all normal driving
conditions. 4th gear (overdrive gear) reduces the
fuel consumption and the engine noise. Engine
braking is applied with reduced throttle.
First to second (1 → 2), first to third (1 → 3), second
to third (2 → 3), second to fourth (2 → 4), third to
fourth (3 → 4), fourth to third (4 → 3), fourth to
second (4 → 2), third to second (3 → 2), third to
first (3 → 1) and second to first (2 → 1) shifts are
all available as a function of vehicle speed, throttle
position and the time change rate of the throttle
position.
Downshifts are available for safe passing by
depress-ing the accelerator. Lockup clutch may be
enabled in 3rd and 4th gears depending on vehicle
type.
3 - Manual 3 provides three gear ratios (first through
third) and prevents the transmission from operating
in 4th gear. 3rd gear is used when driving on long
hill roads or in heavy city traffic. Downshifts are
available by depressing the accelerator.
2 - Manual 2 provides two gear ratios (first and
second). It is used to provide more power when
climbing hills or engine braking when driving down
a steep hill or starting off on slippery roads.
1 - Manual 1 is used to provide the maximum engine
braking when driving down the severe gradients.When NORMAL mode is selected upshifts will occur
to maximize fuel economy. When POWER mode is se-
lected, upshifts will occur to give maximum
performance and the POWER mode indicator light is
switched ON.
When WINTER mode is selected, starting in second
gear is facilitated, the WINTER mode indicator light is
switched ON and the POWER mode indicator light is
switched OFF.
Indicator Light
The indicator light is located on the instrument panel.
Auto shift indicator light comes ON when the ignition
switch ON and shows the gear shift control lever
position.
POWER mode indicator light comes ON when the
POWER mode is selected and when the kickdown
switch is depressed.
WINTER mode indicator light comes ON when the
WINTER mode is selected.
CONTROL SYSTEMS
BTRA M74 4WD automatic transmission consists of
two control systems. One is the electronic control
system that monitors vehicle parameters and adjusts
the transmission performance. Another is the hydraulic
control system that implements the commands of the
electronic control system commands.
ELECTRONIC CONTROL SYSTEM
The electronic control system comprises of sensors, a
TCM and seven solenoids. The TCM reads the inputs
and activates the outputs according to values stored
in Read Only Memory (ROM).
The TCM controls the hydraulic control system. This
control is via the hydraulic valve body, which contains
seven electromagnetic solenoids. Six of the seven
solenoids are used to control the line pressure, operate
the shift valves and the torque converter lock-up clutch,
and to turn ON and OFF the two regulator valves that
control the shift feel.
The seventh solenoid is the proportional or Variable
Pressure Solenoid (VPS) which works with the two regu-
lator valves to control shift feel.
Transmission Control Module (TCM)
The TCM is an in-vehicle micro-processor based trans-
mission management system. It is mounted under the
driver’s side front seat in the vehicle cabin.
The TCM contains:
Processing logic circuits which include a central mi-
croprocessor controller and a back-up memory
system.
Input circuits.
Driving Mode Selector
The driving mode selector consists of a driving mode
selector switch and indicator light. The driving mode
selector is located on the center console and allows
the driver to select the driving mode.
The driving modes available to be selected vary with
vehicle types. Typically the driver should have the
option to select among NORMAL, POWER and
WINTER modes.
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Output circuits which control external devices such
as the Variable Pressure Solenoid (VPS) driver, On/
Off solenoid drivers, a diagnostics output and the
driving mode indicator light.
Processing Logic
Shift schedule and calibration information is stored in
an Erasable Programmable Read Only Memory (EPROM).
Throttle input calibration constants and the diagnostics
information are stored in Electrically Erasable Program-
mable Read Only Memory (EEPROM) that retains the
memory even when power to the TCM is disconnected.
TCM continuously monitors the input values and uses
these, via the shift schedule, to determine the required
gear state. At the same time it monitors, via the solenoid
outputs, the current gear state, whenever the input
conditions change such that the required gear state is
different to the current gear state, the TCM initiates a
gear shift to bring the two states back into line.
Once the TCM has determined the type of gearshift
required the TCM accesses the shift logic, estimates
the engine torque output, adjusts the variable pressure
solenoid ramp pressure then executes the shift.The TCM continuously monitors every input and output
circuit for short or open circuits and operating range.
When a failure or abnormal operation is detected the
TCM records the condition code in the diagnostics
memory and implements a Limp Home Mode (LHM).
The actual limp home mode used depends upon the
failure detected with the object to maintain maximum
drive-ability without damaging the transmission. In
general input failures are handled by providing a default
value. Output failures, which are capable of damaging
the transmission, result in full limp mode giving only
third or fourth gear and reverse. For further details of
limp modes and memory retention refer to the
Diagnostic Trouble Code Diagnosis Section.
The TCM is designed to operate at ambient
temperatures between - 40 and 85 °C (- 40 and 185 °F).
It is also protected against electrical noise and voltage
spikes, however all the usual precautions should be
observed, for example when arc welding or jump
starting.
TCM Inputs
To function correctly, the TCM requires engine speed,
vehicle speed, transmission fluid temperature, throttle
position, gear position and Kickdown Switch inputs to
determine the variable pressure solenoid current ramp
and on/off solenoid states.
KAA5A030
This ensures the correct gear selection and shift feel
for all driving conditions.
The inputs required by the TCM are as follows;
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Engine Speed
The engine speed signal is derived from the Control-
ler Area Network (CAN) via Engine Control Module
(ECM).
Vehicle Speed
The vehicle speed sensor, which is located in the
transfer case, sends the output shaft speed signal
to the Engine Control Module (ECM). The information
is then transferred to the TCM via the CAN.
Transmission Fluid Temperature
The transmission fluid temperature sensor is a
thermistor located in the solenoid wiring loom within
the valve body of the transmission. This sensor is
a typical Negative Temperature Coefficient (NTC)
resistor with low temperatures producing a high
resistance and high temperatures producing a low
resistance.
If the transmission fluid temperature exceeds 135
°C (275 °F), the TCM will impose converter lock-up
at lower vehicle speeds and in some vehicles
flashes the mode indicator light. This results in
maximum oil flow through the external oil cooler and
eliminates slippage in the torque converter. Both
these actions combine to reduce the oil temperature
in the transmission.
Minimum Temperature
(°C)Resistance (Ohms)
-20
0
20
100
135 (Overheat
Mode Threshold)13,638
5,177
2,278
117
75
Maximum
17,287
6,616
2, 723
196
85
Pin No. Wire ColorConnects to
1 Red Solenoid 1
2 BlueSolenoid 2
3 YellowSolenoid 3
4 OrangeSolenoid 4
5 GreenSolenoid 5
6 VioletSolenoid 6
7 BrownSolenoid 7
8 GreenSolenoid 5
9 White Temperature Sensor
10 Red Temperature Sensor
Pin No. Codes and colors in Solenoid Loom
KAA5A040KAA5A050
Gear Position Sensor
The gear position sensor is incorporated in the inhibitor
switch mounted on the side of the transmission case.
Inhibit starting of the vehicle when the shift lever is
in a position other than Park or Neutral
Illuminate the reverse lamps when Reverse is se-
lected
Indicate to the TCM which lever position has been
selected by way of a varying resistance. The gear position sensor is a multi-function switch pro-
viding three functions;
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Solenoids
The TCM controls seven solenoids. Solenoids 1 to 6
(S1 to S6) are mounted in the valve body, while
Solenoid 7 (S7) is mounted in the pump cover.
Solenoid 1 and 2: S1 and S2 are normally open ON/
OFF solenoids that set the selected gear. These
solenoids determine static gear position by
operating the shift valves. Note that S1 and S2
solenoids also send signal pressure to allow or
prohibit rear band engagement.
Solenoid 3 and 4: S3 and S4 are normally open ON/
OFF solenoids that combine to control shift quality
and sequencing. S3 switches the clutch regulator
valve OFF or ON. S4 switches the front band regula-
tor valve OFF or ON. S5 also provides the signal
pressure for the converter clutch regulator valve.
Solenoid 5: S5 is a variable pressure solenoid that
ramps the pressure during gear changes. This sole-
noid provides the signal pressure to the clutch and
band regulator, thereby controlling the shift pres-
sures. S5 also provides the signal pressure for the
converter clutch regulator valve.
Solenoid 6: S6 is a normally open ON/OFF solenoid
that sets the high/low level of line pressure. Solenoid
OFF gives high pressure.
Solenoid 7: S7 is a normally open ON/OFF solenoid
that controls the application of the converter clutch.
Solenoid ON activates the clutch.
Solenoid Logic for Static Gear States
Gear S1 S2
1st ON ON
2nd OFF ON
3 r d OFF OFF
4th ON OFF
Reverse OFF OFF
Neutral OFF OFF
Park OFF OFF
Shift Lever Position Resistance (k
Ω ΩΩ Ω
Ω)
Manual 1 1 ~ 1.4
Manual 221.8 ~ 2.2
Manual 3 3 3 ~ 3.4
Drive4.5 ~ 4.9
Neutral6.8 ~ 7.2
Reverse10.8 ~ 11.2
Park18.6 ~ 19
Kickdown Switch
The Kickdown Switch is used to signal the TCM that
the driver has pressed the acclerator to the floor and
requires a kickdown shift. When this switch is used,
the POWER light comes ON and the POWER shift
pattern is used.
Diagnostic Inputs
The diagnostic control input or K-line is used to initiate
the outputting of diagnostic data from the TCM to a
diagnostic test instrument. This input may also be used
to clear the stored fault history data from the TCM’s
retentive memory. Connection to the diagnostic input
of the TCM is via a connector included in the vehicle’s
wiring harness or computer interface.
Battery Voltage Monitoring Input
The battery voltage monitoring input is connected to
the positive side of the battery. This signal is taken
from the main supply to the TCM.
If the battery voltage at the TCM falls below 11.3 V,
the transmission will adopt a low voltage mode of
operating in which shifts into first gear are inhibited.
All other shifts are allowed but may not occur because
of the reduced voltage. This condition normally occurs
only when the battery is in poor condition.
If the battery voltage is greater than 16.5 V, the trans-
mission will adopt limp home mode and all solenoids
are turned OFF.
When system voltage recovers, the TCM will resume
normal operation after a 30 seconds delay period.
TCM Outputs
The outputs from the TCM are supplied to the compo-
nents described below;
Solenoids
Mode Indicator Light Readings for Resistance / Shift Lever Positions
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SSANGYONG MY2002
Shift To Initiate Shift Typical S5 Current Ramp To Complete Shift
1-2 S1 OFF 750mA to 600mA S4 OFF
S4 ON
1-3 S1 OFF S3 OFF
S2 OFF 850mA to 750mA S4 OFF
S3 ON
S4 ON
1-4 S2 OFF S3 OFF
S3 ON 850mA to 750mA S4 OFF
S4 ON
2-3 S2 OFF 700mA to 500mA S3 OFF
S3 ON S4 OFF
S4 ON
3-4 S1 ON 750mA to 600mA S4 OFF
S4 ON
4-3 S4 ON 750mA to 900mA S1 OFF
S4 OFF
4-2 S3 ON S1 OFF
750mA to 950mA S2 ON
S3 OFF
4-1 S3 ON S2 ON
S4 ON 600mA to 1000mA S3 OFF
S4 OFF
3-2 S2 ON S4 OFF
S4 ON 600mA to 450mA @ 20 kph.
550mA to 400mA @ 60 kph.
800mA to 650mA @ 100 kph.
3-1 S3 ON S1 ON
S4 ON S2 ON
S3 OFF
700mA to 950mA S4 OFF
2-1 S4 ON 800mA to 950mA S1 ON
S4 OFF
Conv. Clutch
ON S7 ON 700mA to 400mA S7 OFF
OFF 600mA to 100mA
Solenoid Operation during Gearshifts
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Solenoid Valve Symbols
(ON/OFF Solenoids)
The solenoid symbol shown adjacent to each solenoid
on the hydraulic system schematics indicates the state
of the oil flow through the solenoid valve with the power
ON or OFF.
Normally Open (NO) Solenoid
POWER ON: Line 500 port is closed. The output port
is open to exhaust at the solenoid valve.
POWER OFF: The exhaust port is closed. The output
port is open to line 500.
Variable Pressure Solenoid Multiplexing System
Friction element shifting pressures are controlled by
the Variable Pressure Solenoid (VPS).
Line pressure is completely independent of shift pres-
sure and is a function of throttle position, gear state
and engine speed.
S5 is a proportional or variable pressure solenoid that
provides the signal pressure to the clutch and band
regulator valves thereby controlling shift pressures.
VPS pressure is multiplexed to the clutch regulator
valve, the band regulator valve and the converter clutch
regulator valve during automatic gearshifts.
A variable pressure solenoid produces a hydraulic
pressure inversely proportional to the current applied.
During a gearshift the TCM applies a progressively
increasing or decreasing (ramped) current to the
solenoid. Current applied will vary between a minimum
oaf 200 mA and a maximum of 1000 mA. Increasing
current decreases output (S5) pressure. Decreasing
current increases output (S5) pressure.
Line 500 pressure, (approximately 440 to 560 kPa), is
the reference pressure for the VPS, and the VPS output
pressure is always below line 500 pressure.
When the VPS is at standby, that is no gearshift is
taking place, the VPS current is set to 200 mA giving
maximum output pressure.
Under steady state conditions the band and clutch
regulator valve solenoids are switched OFF.This applies full Line 500 pressure to the plunger and
because Line 500 pressure is always greater than S5
pressure it squeezes the S5 oil out between the
regulator valve and the plunger. The friction elements
are then fed oil pressure equal to Line 500 multiplied
by the amplification ratio.
When a shift is initiated the required ON/OFF solenoid
is switched ON cutting the supply of Line 500 to the
plunger.
At the same time the VPS pressure is reduced to the
ramp start value and assumes control of the regulator
valve by pushing the plunger away from the valve.
The VPS then carries out the required pressure ramp
and the timed shift is completed by switching OFF the
ON/ OFF solenoid and returning the VPS to the standby
pressure.
This system enables either the band or clutch or both
to be electrically controlled for each gearshift.
Mode Indicator Light
Depending on the application, the mode indicator light
may be used to indicate the mode that has been se-
lected or if an overheat condition exists. The mode
indicator light is usually located on the instrument
cluster.
Communication Systems
CAN
The Controller Area Network (CAN) connects various
control modules by using a twisted pair of wires, to
share common information. This results in a reduction
of sensors and wiring. TCM obtains the actual engine
speed and throttle position, vehicle speed and
accelerator position etc. from ECM via CAN without
any additional sensors.
K-Line
The K-line is typically used for obtaining diagnostic
information from the TCM. A scan tool with a special
interface is connected to the TCM via Data Link
Connector (DLC) and all current faults, stored faults,
runtime parameters are then available. The stored
trouble codes can also be cleared by scan tool.
The K-line can be used for vehicle coding at the
manufacturer’s plant or in the workshop. This allows
for one TCM design to be used over different vehicle
mod-els.
The particular code is sent to the microprocessor via
the K-line and this results in the software selecting the
correct shift and VPS ramp parameters.
Data Link Connector (DLC)
The Data Link Connector (DLC) is a multiple cavity
connector. The DLC provides the means to access the
serial data from the TCM.
The DLC allows the technician to use a scan tool to
monitor the various systems and display the Diagnostic
Trouble Codes (DTCs).
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The DLC connector is located within the driver’s
compartment, directly below the instrument panel on
the driver’s side.
HYDRAULIC CONTROL SYSTEM
The hydraulic controls are located in the valve body,
pump body and main case.
The valve body contains the following;
Manual valve
Three shift valves
Sequence valve
Solenoid supply pressure regulator valve
Line pressure control valve
Clutch apply feed regulator valve
Band apply feed regulator valve
Solenoid S1 to S6
Reverse lockout valveThe pump cover contains the following;
Primary regulator valve for line pressure
Converter clutch regulator valve
Converter clutch control valve
Solenoid S7
The main case contains the following;
B1R exhaust valve
All upshifts are accomplished by simultaneously
switching on a shift valve(s), switching VPS pressure
to the band and/or clutch regulator valve, and then
sending the VPS a ramped current. The shift is
completed by switching the regulators OFF and at the
same time causing the VPS to reach maximum
pressure.
All downshifts are accomplished by switching VPS pres-
sure to the band and/or clutch regulator valve and send-
ing a ramped current to the VPS. The shift is completed
by simultaneously switching the regulators OFF,
switching the shift valves and at the same time causing
the VPS to return to stand-by pressure.
The primary regulator valve is located in the pump
cover and supplies four line pressures; high and low
for forward gears, and high and low for reverse. This
pressure has no effect on shift quality and merely
provides static clutch capacity during steady state
operation. Low pressure can be obtained by activating
an ON/OFF solenoid with high line pressure being the
default mode.
Torque converter lock-up is initiated by toggling the
converter clutch control valve with an ON/OFF solenoid.
The actual apply and release of the clutch is regulated
by the VPS via the converter clutch regulator valve.
The solenoid supply pressure regulator valve provides
reference pressure for all the solenoids.
KAA5A080
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5A-10 AUTOMATIC TRANSMISSION
SSANGYONG MY2002
HYDRAULIC CONTROL CIRCUIT
KAA5A08A