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01-16
4. LIMP HOME MODE
In case of transmission malfunction ▶
If a serious fault occurs in the automatic transmission, the TCU enters the limp home mode to
secure safe driving and protect the automatic transmission.
As power is no longer supplied to the solenoid, the current basic function (P, R, N, D) is
maintained and the 4th gear can be maintained only by the operation of the hydraulic system
without electrical operation.
The ECU communicates with other electric modules with CAN. If a serious fault occurs, the
transmission automatically enters the limp home mode for service.
The TCU monitors all factors which can affect to the performance of the transmission and
diagnose the system according to OBD II regulation. 1.
2.
3.
4.
In case of overheated transmission ▶
The TCU enters the limp home mode when the batter voltage drops below 8 V.
If the transmission is overheated, the shift pattern is changed to the hot mode to cool the
transmission more efficiently.
While the transmission is overheated, the selector lever symbol and engine temperature warning
lamp on the instrument cluster blink until the transmission is cooled down to the normal operation
temperature. If the transmission is excessively overheated, the gear cannot be shifted but
remains in the neutral position. 1.
2.
3.
Towing the vehicle with A/T ▶
The best way to transport the vehicle is to load it to a truck and transport it, especially if the vehicle is
4WD.
If towing the vehicle with the propeller shaft connected, the transmission or oil pump of transfer case
may malfunction, resulting in internal damage due to poor lubrication. -
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01-173680-01
5. ELECTRONIC CONTROL SYSTEM
1) Overview
The transmission control unit (TCU) and its input/output networks control the operations of transmission:
Shift timing
Line pressure
Clutch pressure (shift feel)
Torque converter clutch -
-
-
-
In addition, the TCU receives input signals from certain transmission-related sensors and switches. The
TCU also uses these signals when determining transmission operating strategy. Using all of these input
signals, the TCU can determine when the time and conditions are right for a shift, or when to apply or
release the torque converter clutch. It will also determine the pressure needed to optimise shift feel. To
accomplish this, the TCU operates six variable bleed control solenoids and four ON/OFF solenoids to
control the operations of transmission.
2) Transmission Control Unit (TCU)
The transmission control unit (TCU) is mounted under the driver's seat and controls the operation of the
transmission.
TCU processes the analog information from the internal sensors and the digital information through CAN
communication lines. TCU monitors all the input and output signals. If there is any failure, TCU changes
the system to “Limp Home Mode” and alerts to the driver through the warning lamp on the
instrument cluster.
(1) Hard-wired (Analog) Input/Output
Input/Output Data between TGS Lever and TCU ▶
Position and conditions of gear select lever
Driving moded (Winter or Standard) -
-
Position of inhibitor switch - Input/Output Data between Inhibitor and TCU ▶
6 control signals for variable bleed solenoid
4 control signals for ON/OFF solenoid
Transmission input speed
Transmission output speed
Transmission oil temperature
EMM (Embeded Memory Module) -
-
-
-
-
- Input/Output Data between Automatic Transmission and TCU ▶
Input/Output Data between Self Diagnostic Connector and TCU ▶
Various DTC codes and TCU information -
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07-4
Side View Rear View
1. OVERVIEW
By using the planetary gear sets, two-gears shift type part time transfer case achieves direct connection
when selecting 4WD "HIGH" and 2.48 of reduction gear ratio when selecting 4WD "LOW". The silent
chain in transfer case transfers the output power to front wheels.
The simple operation of switches on instrument panel allows to shift between "2H" and "4H" easily while
driving (for 4L: stop vehicle first). The warning lamp warns the driver when the system is defective.
Front Rear
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07-8
3. SYSTEM LAYOUT
Indicators ▶
4H: 4WD HIGH indicator ON
4L: 4WD LOW indicator ON
2H: Indicator OFF
System failure: 4WD CHECK
warning lamp ON 4WD mode switch ▶
4H: 4 Wheel drive, high speed
4L: 4 Wheel drive, low speed
2H: 2 Wheel drive
TCCU
Solenoid valve
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09-54850-01
3) Parts Arrangement
Part nameVehicle with
CBSVehicle with ABS/EBDVehicle with ESP
HECU
Not appliedAppliedApplied Front wheel speed sensor
Rear wheel speed sensor
ABS warning lamp
EBD indicator
Longitudinal G sensor 2WD: N/A, 4WD: Applied Not applied
Sensor cluster
(Yaw rate sensor,
lateral/longitudinal G sensor)
Not applied Applied
ESP indicator
ESP OFF switch and warning
lamp
Steering wheel angle sensor
4) Components
ABS ESP+ARP
2WD 4WD 2WD 4WD
Whhel speed sensor 4 4 4 4
Sensor cluster N/A N/A Applied Applied
G-sensor N/A Applied N/A N/A
2H G-sensor - Operating - -
4H G-sensor - Operating - -
4L G-sensor - Operating - -
2H sensor cluster - - Operating Operating
4H sensor cluster - - Operating Operating
4L sensor cluster - - Operating Operating
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09-6
LampIndicator/Warning Lamp
Description
EBD warning lamp ON when EBD function is failed
ABS warning lamp ON when ABS function is failed
ESP indicator Blinking when ESP function is operating
ESP OFF indicator ON when the ESP OFF switch is pressed
ESP warning lamp ON when ESP function is failed
ESP buzzer Sound when ESP function is operating
5) Indicators and Warning Lamps for ABS/ESP
Page 588 of 751
10-8
ABS warning lamp
Rear wheel speed sensor
(4WD)
Located at both ends of rear axle.
Rear discRear caliper assembly
(2WD/4WD)
Located on the knuckle.
G-sensor
Located on the floor under center
fascia.
2. COMPONENT
EBD warning lamp
(two indicators come on)
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10-114892-01
4. WARNING LAMPS
1) ABS Warning Lamp
ABS warning lamp module indicates the self diagnosis and malfunction.
ABS warning lamp ON:
When turning the ignition switch to ON position, ABS warning lamp comes on for 3 seconds for
self diagnosis and goes off if the system is OK (initialization mode).
When the system is defective, the warning lamp comes on.
When disengaging the connector, the warning lamp comes on.
ABS is not available during lamp ON. In this condition, Only the conventional brake system
without ABS function is available.
When the communication between warning lamp CAN modules in meter cluster is failed, the
warning lamp comes on. A.
B.
C.
D.
E.
ABS warning lamp (2)
Brake warning lamp
(EBD warning lamp: two indicators come
on simultaneously) (1)