Transfer case SSANGYONG MUSSO 2003 Workshop Manual

5D2-2 TRANSFER CASE (TOD)SCHEMATIC AND ROUTING DIAGRAMS
TOD

TRANSFER CASE (TOD) 5D2-3
T.C.C.U

5D2-4 TRANSFER CASE (TOD)FUNCTION DESCRIPTION
TOD 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.
TOD 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-MagneticClutch). 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.
Function 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 planetarygear set.
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.
Transfer 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 inresponse 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 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 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 TM
Torque 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 Range The highest (numerically lowest = 1 :1) gear ratio between the input and outputsof the Transfer Case.
Low Range The 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 theposition 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 indicatesthat the transmission is in neutral.
Shift Inhibit Speed The vehicle speed above which Transfer Case shifts are disallowed. Vehicle speedis 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 whosedetails 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 5271028309241611292526
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 13216713
1514
K-Line
20
22
23
17 18

TRANSFER CASE (TOD) 5D2-7
1. K-LINE : Communication line for coding and diagnosis with SCANNER.
Classification of Pin No.
Classification
Pin No. Pin Name Description
Power Supply 17,18
Ground
TOD control unit ground
4,19 Battery TOD control unit battery supply : (Fuse No 13,20A)
5 Ignition Ignition ON / OFF
27 Position 1
Position encoder 1 : check of shift motor position
10 Position 2 Position encoder 2 : check of shift motor position
28 Position 3
Position encoder 3 : check of shift motor position
30 Position 4
Position encoder 4 : check of shift motor position
9 4H/4L Switch Transfer case mode input
24 Auto T/M Neutral Check of neutral gear position in Auto T/M 16 Speed 5V supply (TPS / speed sensor)
11 Front Speed
Front speed sensor signal input
Signal Input
29 Rear Speed Rear speed sensor signal input
25 ABS Operation
ABS ON / OFF
6 Position Return
Position encoder ground
13 Speed / TPS Return Ground for speed sensor / TPS
2 2 CAN-L CAN bus low line
23 CAN-H
CAN bus high line
2,15 Motor LO-HI Motor output port
- LO to HI : join with battery
- HI to LO (or motor brake) : join with ground
1,14 Motor HI-LO Motor output port
- HI to LO : join with battery
- LO to HI (or motor brake) : join with ground
3 EMC TOD output
Signal Output
21 4L Illumination Illuminates
“4L ” indicator
7 Diagnosis 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 bya 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 1 Position Code 1/2/3/4
1001 0001 0101 0100 Motor Position
NeutralZone 2
Low
Right Stop

TRANSFER CASE (TOD) 5D2-9
4H/4L Switch Input4H 4H 4H 4H 4H 4H4H4H4H
4L 4L 4L4L 4L 4L4L4L 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 ismade.
3. After a shift has started, the TCCU will power the shift motor until the code for the requested position is read. If an invalidcode 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 Stop Action
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 shiftto 4H under conditions of below 87 rpm in front and rearpropshaft and “Neutral ” position. After succesfully shifting into
4H, stop blinking 4L bulb. Same as above Same as aboveSame as aboveSame as aboveSame 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 aboveSame as aboveSame as above Same as above Same as aboveSame as aboveNo 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 theignition 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, theTCCU 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 selectorswitch) 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 ModeIf 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.
TOD TM
System Operation
The TOD TM
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 tothe 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 positionThe 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 tothe maximum value (88%) which applies the maximum available torque to the front axle.