SSANGYONG MUSSO 1998 Workshop Repair Manual

5D2-4 TRANSFER CASE (TOD)
FUNCTION DESCRIPTION
lTOD System Select Mode (4H and 4L)
4H is the mode when drive normally of which gear ratio is 1:1 and 4L mode distributes power to front and rear
wheels 50:50 of which gear ratio is 2.48:1.
lTOD System Function (select 4H mode)
TOD system controls clutch mechanism to comply with rotation in front and rear propeller shaft and if its difference
exceeds the permissible range, corresponding power is distributed into front wheel through EMC (Electro-Magnetic
Clutch).
Hall effect sensor signals speed on front and rear propeller shafts going through with TOD control unit.
Transfercase clutch coil is activated by variable current on exceeding difference of speed in front and rear propeller
shafts.
lFunction of 4L Mode
When select 4L mode, EMC is locked to apply maximum torque into front and rear propeller shafts. Shift motor
rotates also 4L position by rotation of cam thus propeller shaft torque changes from 1:1 to 2.48:1 by planetary
gear set.
lShift 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.
lTransfer Case
TOD transfer case distributes power into front and rear axle by operation of 4H/4L switch and shift motor.
Shifting 4H to 4L, is performed towards reducing HI-LO collar by means for connection HI-LO shift fork with
output shaft in order to join with planetary gear. Torque transmits input shaft then sun gear rotating front planetary
gear. Front planetary gear join with output shaft and drives LO position.

TRANSFER CASE (TOD) 5D2-5
Definitions
Rear Speed Sensor A Hall Effect speed sensor which produces a square wave. 0-5Vdc signal in
response to a rotating 30 tooth wheel coupled to the rear propshaft inside the
Transfer Case. Each rotation of the rear propshaft will result in 30 speed sensor
pulse.
Front Speed SensorA Hall Effect speed sensor which produces a square wave. 0-5Vdc signal in
response to a rotating 30 tooth wheel coupled to the front propshaft inside the
Transfer Case. Each rotation of the front propshaft will result in 30 speed sensor
pulse.
EMC An Electromagnetic clutch used to control the amount of torque applied to the
front propshaft.
TOD
TMTorque on DemandTM.
Duty Cycle Duty Cycle is the time the EMC is on divided by the period in which it is being
modulated.
Touch-off A minimum amount of duty cycle applied to the EMC.
Front OverrunA condition where the front propshaft is turning at a rate which is faster than the
rear propshaft.
Rear Overrun A condition where the rear propshaft is turning at a rate which is faster than the
front propshaft.
High RangeThe highest (numerically lowest = 1 :1) gear ratio between the input and outputs
of the Transfer Case.
Low RangeThe lowest (numerically highest = 2.48:1) gear ratio between the input and outputs
of the Transfer Case.
4H/4L Switch A switch which selects the desired gear ratio.
Shift Motor Electric motor which changes the Transfer Case range.
Position Encoder A set of 4 Gray code switches which provide feedback to the TCCU indicating the
position of the Shift Motor.
Clutch Interlock Switch A switch on vehicles equipped with a manual transmission which indicates that
the clutch pedal is depressed.
Neutral Safety Switch A switch on vehicles equipped with an automatic transmission which indicates
that the transmission is in neutral.
Shift Inhibit Speed The vehicle speed above which Transfer Case shifts are disallowed. Vehicle speed
is indicated by propshaft speed measurement.

5D2-6 TRANSFER CASE (TOD)
Input/Output diagram
TOD control unit and main wiring harness is linked by 30 pin
connector. Each pin joins with switche and actuator whose
details refer to the below diagram.
Battery Power
Ignition ON/OFF
Position Encoder 1
Position Encoder 2
Position Encoder 3
Position Encoder 4
4H / 4L Switch Signal
A/T “N” Position Signal
Speed / TPS Supply
Front Speed Sensor Input
Rear Speed Sensor Input
ABS Operation Signal
Brake Switch Signal
4
5
27
10
28
30
9
24
16
11
29
25
26
19
CAN H
CAN L
Shift Motor output port
(LO-HI)
Shift Motor output port
(HI-LO)
EMC
'4L' Indicator
Position Return
'4WD CHECK' IND
TPS/speed Sensor Ground
(Speed / TPS Return)
2
1
3
21
6
7
13 15
14
K-Line20 22
23
17
18

TRANSFER CASE (TOD) 5D2-7
1. K-LINE : Communication line for coding and diagnosis with SCANNER.
Classification of Pin No.
ClassificationPin No. Pin NameDescription
Power Supply17,18Ground
TOD control unit ground
4,19Battery
TOD control unit battery supply : (Fuse No 13,20A)
5IgnitionIgnition ON / OFF
27Position 1
Position encoder 1 : check of shift motor position
10Position 2
Position encoder 2 : check of shift motor position
28Position 3
Position encoder 3 : check of shift motor position
30Position 4
Position encoder 4 : check of shift motor position
94H/4L SwitchTransfer case mode input
24Auto T/M Neutral
Check of neutral gear position in Auto T/M
16Speed5V supply (TPS / speed sensor)
11Front Speed
Front speed sensor signal input Signal Input
29Rear Speed
Rear speed sensor signal input
25ABS Operation
ABS ON / OFF
6Position Return
Position encoder ground
13Speed / TPS ReturnGround for speed sensor / TPS
22CAN-LCAN bus low line
23CAN-HCAN bus high line
2,15Motor LO-HIMotor output port
- LO to HI : join with battery
- HI to LO (or motor brake) : join with ground
1,14Motor HI-LO
Motor output port
- HI to LO : join with battery
- LO to HI (or motor brake) : join with ground
3EMCTOD output
Signal Output
214L IlluminationIlluminates “4L” indicator
7Diagnosis Display
4WD check lamp illuminator
- Upon defect ; Ground circuit
20K-LINE1)Diagnosis

5D2-8 TRANSFER CASE (TOD)
Position Code 1/2/3/4
111 0
1010
0010
0000
111 0
Initial Operation of TOD Control Unit
When ignition “ON”, “4L” and "4WD check" lamps illuminates
for 0.6second to check bulb in instrument panel, then perform
diagnosis of system.
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.
Notice
1. All other position codes are invalid
2. Position Input Open Circuit (> 4.5V) = 1
3. Position Input shorted to Speed/Position Return (< 0.5V) = 0
Motor Position
Left Stop
Left of High
High
Right of High
Zone 1Position Code 1/2/3/4
1001
0001
0101
0100Motor Position
Neutral
Zone 2
Low
Right Stop

TRANSFER CASE (TOD) 5D2-9
4H/4L Switch Input
4H
4H
4H
4H
4H
4H
4H
4H
4H
4L
4L
4L
4L
4L
4L
4L
4L
4L
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 follows
2. A command to shift will only be acted upon if the TCCU is
reading a valid code at the time the command 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 energized for a
maximum of 5 seconds.Motor Position
Left Stop
Left of High
High
Right of High
Zone 1
Neutral
Zone 2
Low
Right Stop
Left Stop
Left of High
High
Right of High
Zone 1
Neutral
Zone 2
Low
Right StopAction
No action required. 4L bulb off.
No action required. 4L bulb off.
No action required. 4L bulb off.
Blink 4L bulb. After the shift conditions are met, attempt a shift
to 4H under conditions of below 87 rpm in front and rear
propshaft and “Neutral” position. After succesfully shifting into
4H, stop blinking 4L bulb.
Same as above
Same as above
Same as above
Same as above
Same as above
Blink 4L bulb. After the shift conditions are met, attempt a shift
to 4L. After succesfully shifting into 4L, stop blinking 4L bulb.
Same as above
Same as above
Same as above
Same as above
Same as above
Same as above
No action required. 4L bulb on.
No action required. 4L bulb on.

5D2-10 TRANSFER CASE (TOD)
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, neutral switch, speed sensors, position encoder, and ignition switch.
A range change is initiated when
1. The 4H/4L Switch is changed from 4H to 4L or from 4L to 4H.
2. The motor position (as indicated by the position encoder) does not match the 4H/4L Switch immediately after the
ignition is turned on.
1. 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:
a. The transmission is in neutral for 2 seconds after the shift is requested.
b. Both propshaft speeds are below 87 rpm (2580 pulses/minute).
If the transmission is taken out of neutral before 2 seconds has elapsed, or either propshaft 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.
2. 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:
a. The motor reaches its destination.
b. The motor is on for 5 seconds without reaching its destination. The shift has failed and the TCCU will respond
as default mode.
c. 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, propshaft speeds, and transmission neutral inputs are
ignored.
3. Indicator Function
Once a range change has been initiated the 4L 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 4L Indicator will be illuminated if the motor is in Low and it will be
turned off if the motor is in High.
4L Indicator illuminates as below figure.
· 4H ® 4L

@ : shift is completed
· 4L ® 4H

@ : shift is completed

TRANSFER CASE (TOD) 5D2-11
4. Electric Shift Default Mode
If the motor fails to reach its destination, the TCCU will attempt the following (in order):
a. The TCCU will wait 3 seconds then attempt the shift again.
b. If the second attempt to reach the destination fails the TCCU will wait 3 seconds then attempt to rotate the
motor back to the original position. If successful, all future shifts will be inhibited until the Ignition is cycled.
c. If the attempt to return to the original position fails, the TCCU will wait 3 seconds then attempt to rotate the
motor to the original position again. If the second attempt to return to the original position is successful, the
“4WD CHECK” lamp will be illuminated, and all future shifts will be inhibited until the Ignition is cycled.
d. If the second attempt to return to the original position fails the motor will be turned off, the “4WD CHECK” lamp
will be illuminated, and all future shifts will be inhibited until the Ignition is cycled.
TODTM System Operation
The TODTM System is responsible for distributing torque between the front and rear axles. The TCCU monitors the
propshaft speeds, operating range (High/Low), and ABS activity and then applies a calculated amount of torque to
the front axle by Pulse Width Modulating the current applied to the EMC.
1. Touch-off Torque
The minimum EMC Duty Cycle is based on the vehicle speed and throttle position
The TCCU receives the TPS signal from the following sources:
On vehicles equipped with CAN, the TCCU receives the TPS signal from the CAN bus.
2. When Slip Detection
The TCCU continuously monitors the front and rear propshaft speeds to detect wheel slip.
3. Wheel Slip Control
When wheel slip is detected the TCCU controls the EMC duty cycle 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.
4. 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.
5. 4L Strategy
When the system is operating in 4L, the TCCU continues TOD
TM (operation provided that the propshaft speed is
below 175 rpm (5220 pulses/minute)). 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.

5D2-12 TRANSFER CASE (TOD)
Pin
1
2
3
4
5
6
7
8Function
Motor HI-LO
Motor LO-HI
EMC
Battery (+)
Ignition
Position Return
Diagnosis Display
-Pin
9
10
11
12
13
14
15
16Function
HI / LO Switch
Position 2
Front Speed
TPS Supply (Diesel)
Speed/TPS Return
Motor HI-LO
Motor LO-HI
Speed ReferencePin
17
18
19
20
21
22
23
24Function
Ground
Ground
Battery (+)
K-LINE
4L Illumination
CAN-H
CAN-L
Auto T/M, NeutralPin
25
26
27
28
29
30
-
-Function
ABS Input
Brake Switch
Position 1
Position 3
Rear Speed
Position 4
-
-
TOD CONTROL UNIT
Shape and function of TOD Control Unit

TRANSFER CASE (TOD) 5D2-13
Speed Sensor/Clutch Coil and Motor Connector
Speed senso /clutch coil and shift motor connector locate upper
backside transfer case (upper part of shift motor).
- Shift motor connector : Black
- Speed sensor and clutch coil connector : White
Shift Mtor Connector Speed Sensor/Clutch Coil Connector
Rear View for Connector
Pin
A
B
C
D
E
F
GFunction
Position 4
Motor (Counter-Clockwise)
Position 3
Position 2
Position 1
Position Retum
Motor (Clockwise)Pin
H
I
J
K
L
M
NFunction
Clutch Coil (EMC)
Front Speed Return
Front Speed
Front Speed Sensor Supply
Rear Speed Sensor Supply
Rear Speed
Rear Speed Return Rear View for Connector