SsangYong Musso. Manual - part 517

TRANSFER CASE (TOD)  5D2-15

DIAGNOSIS

While the 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 a diagnostic connector (K-line) serial communications using SCAN-
100.

DIAGNOSTIC TESTS

1.TCCU Internal Function

When the Ignition is turned on the TCCU tests its ROM and 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 EEPROM memory 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.

2.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.

a. A shift motor fault when the motor is off is defined as follows:

Motor H-L shorted to Ground

Motor L-H shorted to Ground

Motor open circuit

b. A shift motor fault when the motor is energized is defined as follows:

Motor H-L shorted to Ground

Motor L-H shorted to Ground

Motor H-L shorted to Motor L-H

Motor open circuit

c. 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.

d. If no shifts are in progress when a failure occurs the TCCU will not respond to any shift commands.

e. If a shift command has been received, but not acted upon when a failure occurs the TCCU will cancel the

command and not respond to any subsequent shift commands.

f. 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.

5D2-16  TRANSFER CASE (TOD)

g. If the shift motor/position encoder assembly failure (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.

h. 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.

3. 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:

a. 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.

b. 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 4L.

c. 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.

4. 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:

a. 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.

b. 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 4L.

c. All Electric Shift activity is halted until the Ignition is cycled. If a shift is in progress it will be completed.

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.

5. Both Speed Sensor Faulty

If both the Front and Rear Speed Sensors are faulty continuously for 0.5 seconds the “4WD CHECK” lamp is
illuminated. The TCCU then responds as follows:

a. If the system is in High Range the TCCU sets the EMC Touch Off level based on a vehicle speed of 0 and wheel

slip control is suspended.

b. If the system is in Low Range, the EMC Duty Cycle is set to maximum until the system is shifted out of 4L.

c. All Electric Shift activity is halted until the Ignition is cycled. If a shift is in progress it will be completed.

If both Speed Sensors recover 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.

6. EMC Test

The EMC is tested for open circuit or short circuit to ground. If a fault is detected continuously for 0.8 second the
“4WD CHECK” lamp is turned on and all TOD

TM

 activity is halted.

If the EMC recovers continuously for 0.8 second the TCCU will function normally. The “4WD CHECK” lamp is
turned off but the fault code will remain in memory.

TRANSFER CASE (TOD)  5D2-17

Classification

TCCU

EMC

Speed Sensor

Shift Motor

Position Encoder

DIAGNOSTIC TROUBLE CODES
(DTC’s)

1. Diagnostic Trouble Code Retention

The first time a fault is detected a DTC is stored in the TCCU’s
Non-Volatile memory. This DTC will remain in memory until
the TCCU is instructed to erase DTC’s by SCAN-100. DTC’s
will not be erased by disconnecting power to the TCCU.

2. Diagnostic Trouble Code Assignments

Code

1714

1715

1716

1721

1722

1731

1732

1733

1734

1735

1736

1741

1742

1743

1750

1751

1752

1753

1754

Description

EEPROM Checksum Fault

TPS Loss of Signal

TPS Out of Range

EMC Open / Short to Battery

EMC Short to ground

Front Speed Sensor Voltage Low

Front Speed Sensor Voltage High

Rear Speed Sensor Voltage Low

Rear Speed Sensor Voltage High

Speed Sensor Reference Voltage Low

Speed Sensor Reference Voltage High

Motor Open / Shorted to Battery

Motor Output Shorted to Ground

Shift System Timeout

General Position Encoder Fault (Invalid Code)

Position 1 Shorted to Ground

Position 2 Shorted to Ground

Position 3 Shorted to Ground

Position 4 Shorted to Ground

5D2-18  TRANSFER CASE (TOD)

CODING

Coding Tool

SCANNER

Connection of Coding Tool

Construct SCANNER into diagnosis connector (20 pins) near fuse box in engine room as below figure.

1 Diagnosis Connector

2 SCANNER

Notice

Coding ; An input activity of data for the proper
performance by matching specification, devices and
system with control unit.