2013 SSANGYONG KORANDO clutch control

5. TRANSAXLE ELECTRONIC CONTROL SYSTEM
1) General Information
The transmission control unit (TCU) and its input/output network control the following transmission
operations:
Shift timing
Line pressure
Clutch pressure (shift feel)
Torque converter clutch -
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also uses these signals when determining transaxle 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 transaxle
operation.
2) TCU (Transmission Control Unit)
The transaxle control unit (TCU) is mounted
under the driver's seat and controls the operation
of the transaxle.
The TCU is activated and deactivated by the
ignition power supply and is connected to the
transaxle link harness by a 26 pin connector. The
TCU processes information received from internal
sensors and signals received across the CAN
bus in analogue and digital forms such as:
Transaxle input speed
Transaxle output speed
Accelerator pedal position
Gear selector position
Engine torque
Engine speed
Transaxle fluid temperature
Brake pedal status
Engine oil temperature
Engine coolant temperature
Ambient air temperature
Barometric pressure -
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This information is used by the TCU to decide which shift pattern to select and for shift energy
management. Electro-hydraulic solenoid valves and variable bleed solenoids control the transaxle gear
changes.
Six variable bleed solenoids and four on/off solenoids are used to direct transaxle fluid flow to control the
fluid pressure within the three clutches and two bands. Separate pressure regulators are used
exclusively for torque converter clutch control and main transaxle line pressure.
The TCU monitors all TCU inputs and outputs to confirm correct system operation. If a fault occurs the
TCU is able to perform default action and inform the driver of the problem through the instrument cluster
warning lights. Detailed information is available via trouble codes which can be read with the service tool.

3660-01
1. ABBREVIATION
No Abbreviation Name
1 DTC Diagnostic trouble code
2 TCU Transmission control unit
3 ATF Automatic transmission fluid
4 DC Damper clutch
5 PCSV Pressure control solenoid valve
6 UD Under drive
7OD Over drive
8 LR Low reverse
9 LP Line pressure
10 SOL Solenoid
11 VFS Variable force solenoid
12 PG-A Input speed sensor
13 PG-B Output speed sensor

2. GENERAL INFORMATION
Automatic transaxle (6F24)
The Model 6F24 six speed automatic transaxle is
available in two variants: four wheel drive and two
wheel drive.
Six forward speeds
One reverse gear
A toruqe converter with an integral converter lock-
up clutch with slip control capabilities
Planetary gear-set (3EA)
Clutches (2EA)
Brake (3EA)
O.W.C (1EA)
All hydraulic functions are directed by electronic
solenoids to control: -
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Engagement feel
Shift feel
Shift scheduling
Modulated torque converter clutch
applications 1)
2)
3)
4) Inhibitor switch
Oil pan
Torque converter
TCU (located under driver's seat)
TCU is located under the driver's seat and controls
the transaxle operations.
TCU receives and uses the signals from sensors
and switches through CAN bus with analog and
digital types.
E-coupling unit
TCU

3660-01
1. OVERVIEW
2WD4WD
The Model 6F24 6 speed automatic transaxle is electronically controlled. The control system is
comprised of the following components:
External transaxle control unit (TCU)
Input and output speed sensors
Six variable force solenoids(VFS) and two on/off solenoids
Torque converter
ATF temperature sensor -
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TCU controls the oil pressure for various internal clutches and brakes to select the gear. It also controls
the electronic elements, shift pressure and torque converter slip. If the system is defective, TCU provides
FMEC (Failure Mode Effect Control) to maintain the functionality of transaxle. This keeps the basic
function of transaxle (gear selection) even when there are failure in controls and power supply.
There are selector shaft position sensor (inhibitor switch) and oil temperature sensor in transaxle. In
manual mode, TCU receives the information from TGS (Transmission Gear Selector) through PCB
(Printed Circuit Board) when driver selects the manual shift mode. TCU communicates with other electric
control modules through CAN. In order to ensure a safe driving state and to prevent damage to the
automatic transmission, TCU switches to Limp-Home mode in the event of critical faults.

3660-01
2) Transaxle Cooling
The transaxle cooling system ensures rapid warm-up and constant operating temperature resulting in
reduced fuel consumption and refined shift quality.
It also includes a cooler by-pass within the hydraulic system to allow sufficient lubrication to the transaxle
drivetrain in the event of a blockage in the transaxle cooler.
3) Shift Strategy
Gear Change
Transaxle gear change is controlled by the
TCU. The TCU receives inputs from various
engine and vehicle sensors to select shift
schedules and to control the shift feel and
torque converter clutch (TCC) operation at each
gear change.
Coast down
Coast down down shifts occur at 0% pedal
when the vehicle is coasting down to a stop.
Torque Demand
Torque demand down shifts occur
(automatically) when the driver demand for
torque is greater than the engine can provide at
that gear ratio. If applied, the transaxle will
disengage the TCC to provide added
acceleration.

4. LIMP HOME MODE
When the transaxle is defective
In the event of a system fault, the TCU also provides for failure mode effect control (FMEC) to maintain
maximum functional operation of the transaxle. (There are 3 FMEC modes, mechanical limp-home
mode, electrical limp-home mode, limp-home mode C.)
In the event of a total loss of control or electrical power, the basic transaxle functions (Park, Reverse,
Neutral and Drive) are retained. The 4th and reverse gear ratios with the torque converter clutch in the
unlocked state are the retained gear states the hydraulic system supports without any electrical
assistance. (Mechanical limp-home)
If the speed sensor circuit is failed, the gear is fixed to 4th gear, but manual shifting
If the inhibitor switch signals are invalid, shifting to1st and 2nd gear is forbidden. (Limp-home C)
The TCU communicates with other vehicle electronic control modules by the controller area network
(CAN). If a major fault is developed, the transaxle may not accomplish the intelligent shift control. The
TCU controls the transaxle with preset values.
The TCU also provides for transaxle diagnostics, which meet the requirements of OBD II regulation,
monitoring all components which may effect vehicle emissions. 1.
2.
3.
4.
5.
6.
Towing the automatic transaxle equipped vehicle
Flat-bed equipment is the best method of moving a disabled vehicle to avoid any damages.
For AWD vehicle: The vehicle must be towed with a wheel lift and dollies or flatbed equipment with
all the wheels off the ground.
For 2WD vehicles: It is acceptable to tow the vehicle with the rear wheels on the ground without
dollies and the front wheels off the ground. When being towed by a commercial towtruck and
wheel dollies are not available, the front of the vehicle should be lifted, not the rear. -
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3660-01
5. TRANSAXLE ELECTRONIC CONTROL SYSTEM
1) General Information
The transmission control unit (TCU) and its input/output network control the following transmission
operations:
Shift timing
Line pressure
Clutch pressure (shift feel)
Torque converter clutch -
-
-
-
also uses these signals when determining transaxle 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.
2) TCU (Transmission Control Unit)
The transaxle control unit (TCU) is mounted
under the driver's seat and controls the operation
of the transaxle.
Internal sensors and signals received across the
CAN bus in analogue and digital forms such as:
Transaxle input speed
Transaxle output speed
Accelerator pedal position
Gear selector position
Engine torque
Engine speed
Transaxle fluid temperature
Brake pedal status
Engine oil temperature
Engine coolant temperature
Ambient air temperature
Barometric pressure -
-
-
-
-
-
-
-
-
-
-
-
The TCU monitors all TCU inputs and outputs to confirm correct system operation. If a fault occurs the
TCU is able to perform default action and inform the driver of the problem through the instrument cluster
warning lights. Detailed information is available via trouble codes which can be read with the service tool.