1997 SSANGYONG KORANDO transfer case

SSANGYONG MY2002
5D1-4 TRANSFER CASE
COMPONENTS OF THE TOD
TRANSFER CASE SYSTEM
Shift Motor
It locates backside transfer case, which drives rotary
helical cam. When mode select switch changes to 4L,
shift fork is on position for 2.48 : 1 by rotation of helical
cam.
Rear Speed Sensor
A hall effect speed sensor which produces a square
wave. 0 to 5 volts direct current signal in response to
a rotating 30-tooth wheel coupled to the rear propeller
shaft inside the transfer case. Each rotation of the rear
propeller shaft will result in 30 speed sensor pulse.
Front Speed Sensor
A hall effect speed sensor which produces a square
wave. 0 to 5 volts direct current signal in response to
a rotating 30-tooth wheel coupled to the front propeller
shaft inside the transfer case. Each rotation of the front
propeller shaft will result in 30 speed sensor pulse.
Electro-Magnetic Clutch
An electromagnetic clutch used to control the amount
of torque applied to the front propeller shaft.
Position Encoder
A set of 4 gray code switches which provide feedback
to the TCCU indicating the position of the shift motor.
Clutch Pedal Position Switch
A switch on vehicles equipped with a manual transmis-
sion which indicates that the clutch pedal is depressed
Park/Neutral Position Switch
A switch on vehicles equipped with an automatic trans-
mission which indicates that the transmission is in neu-
tral.
4H/4L Switch
A switch selects the desired gear ratio.
DEFINITION OF TERMINOLOGY
Shift Inhibit Speed
The vehicle speed limit, which transfer case shifts, is
disallowed. Vehicle speed is indicated by propeller
shaft speed measurement.
Duty Cycle
Duty cycle is the time the electromagnetic clutch is on
divided by the period in which it is being modulated.
Touch-off
A minimum amount of duty cycle applied to the electro
magnetic clutch.
Front Overrun
A condition where the front propeller shaft is turning at
a rate which is faster than the rear propeller shaft.
Rear Overrun
A condition where the rear propeller shaft is turning at
a rate which is faster than the front propeller shaft.
High Range
The highest (numerically lowest = 1 : 1) gear ratio be-
tween the input and outputs of the transfer case.
Low Range
The lowest (numerically highest = 2.48 : 1) gear ratio
between the input and outputs of the transfer case.
OPERATION OF THE TOD
TRANSFER CASE SYSTEM
Initial Operation of TOD Control Unit
When ignition switch is turned to ON, 4WD LOW and
4WD CHECK lamp illuminates for 0.6 second to check
bulb in instrument panel, then perform diagnosis of
system. Refer to “Self-Diagnosis Test” in this section.
Electric Shift System Operation
The electric shift system is responsible for changing
the transfer case gear ratio by controlling the electric
shift motor. The TCCU monitors the 4H/4L switch, park/
neutral position switch, speed sensors, position
encoder, and ignition switch.
A range change is initiated when:
The 4H/4L switch is changed from 4H to 4L or from
4L to 4H.
The motor position (as indicated by the position
encoder) does not match the 4H/4L switch
immediately after the ignition is turned on.
Shift Criteria
When a range change is initiated a diagnostic test will
be completed on the motor, speed sensors, and
position encoder. If the diagnostic test fails, the shift
will not be attempted. If all components are operating
properly, the TCCU will attempt a range change after
the following shift criteria are met:
The transmission is in neutral for 2 seconds after
the shift is requested.
Both propeller shaft speeds are below 87 rpm (2580
pulses/minute). If the transmission is taken out of
neutral before 2 seconds has passed, or either
propeller shaft speed increases above the limit, the
shift will be suspended and the 4L indicator will
continue to blink until the criteria are met again or
the 4H/4L switch is returned to the original position.
Range Change
When the shift criteria are met, the motor is rotated in
the appropriate direction (as determined by the selector
switch) until one of the following occurs:

TRANSFER CASE 5D1-5
SSANGYONG MY2002
The motor reaches its destination.
The motor is on for 5 seconds without reaching its
destination. The shift has failed and the TCCU will
respond as default mode.
A fault occurs with either the motor or position
encoder. Refer to the diagnosis requirement.
When the motor is energized, the Ignition, 4H/4L
switch, propeller shaft speeds, and transmission
neutral inputs are ignored.
Indicator Function
Once a range change has been initiated the 4WD LOW
indicator will begin to blink at a rate of 0.3 seconds
on, 0.3 seconds off until the shift is completed or
canceled. If a successful shift has been completed,
the 4WD LOW indicator will be illuminated if the motor
is in low range and it will be turned off if the motor is in
high range.
4WD LOW indicator illuminates as below figure.
KAA5D000
TODTM System Operation
The TODTM System is responsible for distributing torque
between the front and rear axles. The TCCU monitors
the propeller shaft speeds, operating range (high/low),
and ABS activity and then applies a calculated amount
of torque to the front axle by pulse width modulating
(PWM) the current applied to the electromagnetic clutch
(EMC).
Touch-off Torque
The minimum EMC duty cycle is based on the vehicle
speed and throttle position. The TCCU receives the
throttle position (TP) sensor signal from the engine con
trol module (ECM) through CAN bus line.
Wheel Slip Detection and Control
The TCCU continuously monitors the front and rear pro-
peller shaft speeds to detect wheel slip.
When wheel slip is detected the TCCU controls the
EMC duty cycles as necessary until the wheel slip is
reduced below the allowable limit. The EMC duty cycle
will then be reduced to the touch-off value.Brake/ABS Strategy
When the ABS System is active, the EMC duty cycle
is set to a fixed duty cycle (30%) to aid in braking
without counteracting the ABS System.
4L Strategy
When the system is operating in 4WD low range, the
TCCU continues TOD
TM operation provided that the pro
peller shaft speed is below 175 rpm (5220 pulses/min-
ute). When the speed increases above 175 rpm, the
EMC duty cycle is set to the maximum value (88 %)
which applies the maximum available torque to the front
axle.
Position Encoder
The position encoder is used by the TCCU to determine
the position of the shift motor. Each motor position is
identified by a position code as shown.
Motor Position
Left Stop
Left of High
High
Right of High
Zone 1
Neutral
Zone 2
Low
Right Stop Position code 1/2/3/4
1111
1010
0010
0000
1110
1001
0001
0101
0100
Notice:
All other position codes are invalid
Position input : open circuit (> 4.5V) = 1
Position input : Shorted to speed/position return
(< 0.5V) = 0
Position Sensor Interpretation
1. When the module powers up, it will read the position
sensor and the 4H/4L switch input and respond to
the possible codes as following tables.
2. A command to shift will only be acted upon if the
TCCU is reading a valid code at the time the com-
mand to shift is made.
3. After a shift has started, the TCCU will power the
shift motor until the code for the requested position
is read. If an invalid code is read, the TCCU will go
into a default mode.
4. During a shift attempt, the shift motor will be ener-
gized for a maximum of 5 second

SSANGYONG MY2002
5D1-6 TRANSFER CASE
4H
4H
4H
4H
4H
4H
4H
4H
4H
4H
4H
4H
4H
4H
4H
4H
4H
4HLeft Stop
Left of High
High
Right of High
Zone 1
Neutral
Zone 2
Low
Right Stop
Left Stop
Left of High
High
Right to High
Zone 1
Neutral
Zone 2
Low
Right stopNo action required. 4WD LOW indicator off.
Blink 4WD LOW indicator.
After the shift conditions are input, attempt a shift to 4H mode if follow-
ing conditions are maintained for 2 seconds conditions are maintained
for 2 seconds.
Shift lever position is in neutral.
The speed of front and rear propeller shaft is below 87 rpm.
After successfully shifting into 4L mode, stop blinking 4WD LOW indicator.
Blink 4WD LOW indicator.
After the shift conditions are input, attempt a shift to 4L mode if following
conditions are maintained for 2 conditions are maintained for 2 seconds.
Shift lever position is in neutral.
The speed of front and rear propeller shaft is below 87 rpm.
After successfully shifting into 4L mode, stop blinking 4WD LOW indicator.
No action required. 4WD LOW indicator on.
4H/4L Switch
InputAction Motor Position

TRANSFER CASE 5D1-7
SSANGYONG MY2002
COMPONENT LOCATOR
TORQUE ON DEMAND (TOD) TYPE TRANSFER CASE
KAA5D010
1 Transmission
2 Transfer Case
3 Rear Propeller Shaft
4 Bolt5 Bolt
6 Front Propeller Shaft
7 Bolt

SSANGYONG MY2002
5D1-8 TRANSFER CASE
TRANSFER CASE DISASSEMBLED VIEW
KAA5D020

TRANSFER CASE 5D1-9
SSANGYONG MY2002
1 Bearing
2 Bushing
3 Carrier Assembly
4 Sun Gear
5 Thrust Plate
6 Input Shaft
7 Output Shaft Thrust Washer
8 Bearing
9 Snap Ring
10 High-Low Collar
11 Rear Output Shaft
12 Oil Strainer
13 Coupling Hose
14 Hose Clamp
15 Pump Assembly
16 Thrust Washer
17 Sprocket, Drive (214t)
18 lutch Pack Assembly
19 Insulator Washer
20 Armature
21 Snap Ring
22 Wave Washer
23 Apply Cam
24 Ball
25 Cam And Coil Assembly
26 Nut, Metric (2)
27 Output Shaft Yoke Washer
28 Oil Seal
29 Case Flange
30 Bolt
31 Upper Speed Sensor (Rear)
32 Nut
33 Washer
34 Bolt (M10 X 1.5 X 30)
35 Tag, Identification
36 Thrust Bearing
37 Clutch Coil Assembly
38 Fork, Reduction Shift39 Shift Rail
40 Shaft, Shift
41 Spacer
42 Torsion Spring
43 Spring, Electric Shift
44 Transfer Case Shift Motor
45 Bolt
46 J-Clip
47 Connector Retainer
48 Bolt
49 Support Stud
50 Lower Speed Sensor (Front)
51 Plug
52 Identification Decal
53 Case
54 Tone Wheel, Lower
55 Chain, Drive
56 Sprocket, Driven (24t)
57 Oil Pan Magnet
58 Case Flange And Output Shaft
59 Case Assembly
60 Barb, Breather
61 Spirol Pin
62 Oil Seal
63 Pin, Dowel
64 Ring Gear
65 Retaining Ring
66 Snap Ring
67 Bearing
68 Snap Ring
69 Bearing
70 Speedometer Drive Gear
71 Facing, Shift Fork
72 Upper Tone Wheel
73 Oil Seal
74 Bearing Sleeve
75 Bearing

SSANGYONG MY2002
5D1-10 TRANSFER CASE
TOD CONTROL UNIT
KAA5D030
1 Transfer Case Control Unit (TCCU)

TRANSFER CASE 5D1-11
SSANGYONG MY2002
DIAGNOSIS
While the transfer case control unit (TCCU) is active it
periodically monitors its inputs and outputs. If a fault
is detected the 4WD CHECK lamp is illuminated and a
fault code is stored in the TCCU memory.
When requested, fault codes are downloaded to scan
tool through a diagnostic connector (K-line) serial com
munication.
SELF-DIAGNOSTIC TESTS
TCCU Internal Function
When the ignition is turned on the TCCU tests its read
only memory (ROM) and random access memory
(RAM). If there is a fault, the TCCU immediately resets
itself and re-tests the ROM and RAM. If the fault
persists the TCCU continues to reset and re-test until
the fault is corrected or the ignition is turned off. All
TCCU functions are inhibited until the fault is corrected.
The 4WD CHECK lamp is not illuminated if there is a
ROM or RAM fault.
If the ROM/RAM passes the electronically erasable
programmable read only memory (EEPROM) is tested.
If there is a fault the 4WD CHECK lamp is illuminated
and the TCCU continues to operate using the default
calibration data stored in ROM. Fault codes are not
stored when there is an EEPROM fault.
An EEPROM fault can only be cleared by cycling
ignition OFF-ON.
Shift Motor Assembly Test
If the TCCU detects a shift motor or position encoder
fault continuously for one second the 4WD CHECK
lamp is turned on and the appropriate fault code is
stored in memory.
1. A shift motor fault when the motor is off is defined
as follows:
Motor HI-LO circuits are shorted to ground.
Motor LO-HI circuits are shorted to ground.
Motor circuits are open.
2. A shift motor fault when the motor is energized is
defined as follows:
Motor HI-LO circuits are shorted to ground.
Motor LO-HI circuits are shorted to ground.
Motor HI-LO circuits are shorted to motor LO
HI circuits.
Motor circuits are open.
3. A position encoder fault is defined as follows:
Any position code which does not correspond
to the valid 9 codes.
A short to ground on any of the encoder lines.
4. If no shifts are in progress when a failure occurs
the TCCU will not respond to any shift commands.5. If a shift command has been received but not
acted upon when a failure occurred the TCCU
would cancel the command and not respond to
any subsequent shift commands.
6. If a shift command is in progress when an invalid
position code is confirmed it will be halted and
the TCCU will turn the motor toward the high
position. Afterwards the TCCU will not respond to
any shift commands.
7. If the shift motor or position encoder assembly
failures, other than a motor failure which occurs
when the motor is energized, recovers continuously
for one second the TCCU will function normally.
The 4WD CHECK lamp is turned off but the fault
code will remain in memory.
8. A motor failure (i.e. open or short circuit) which
occurs when the motor is energized can only be
cleared by cycling the ignition OFF-ON.
Front Speed Sensor Test
If a front speed sensor fault is detected continuously
for 0.5 second the 4WD CHECK lamp is illuminated.
The TCCU then responds as follows:
1. If the system is in high range the TCCU uses the
rear speed sensor to determine the EMC touch off
level and wheel slip control is suspended.
2. If the system is in low range, the EMC duty cycle
is set to maximum, independent of vehicle speed,
until the system is shifted out of low range.
3. All electric shift activity is halted until the Ignition
is cycled. If a shift is in progress it will be
completed.
If the front speed sensor recovers continuously for O.5
second the TCCU will function normally. The 4WD
CHECK lamp is turned off but the fault code will remain
in memory.
Rear Speed Sensor Test
If a rear speed sensor fault is detected continuously
for 0.5 second the 4WD CHECK lamp is illuminated.
The TCCU then responds as follows:
1. If the system is in high range the TCCU uses the
front speed sensor to determine the EMC touch
off level and wheel slip control is suspended.
2. If the system is in low range, the EMC duty cycle
is set to maximum independent of vehicle speed
until the system is shifted out of low range.
3. All electric shift activity is halted until the Ignition
is cycled. If a shift is in progress it will be
completed.
4. If the rear speed sensor recovers continuously for
0.5 second the TCCU will function normally. The
4WD CHECK lamp is turned off but the fault code
will remain in memory.