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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.
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2. FEATURES
1) Advantages
Early Downshift with Hard Braking and Skip Shifts
When heavy braking is detected, the transaxle downshifts early and skips gears to provide increased
engine braking to provide gear selection for tip-in.
Gear Hold going Uphill/Downhill
If the accelerator pedal is released when traveling uphill, upshifts are prevented to reduce busyness on
grades. If the accelerator pedal is released when traveling downhill, upshifts are prevented to enhance
engine braking.
Drive and Reverse Engagement
A soft engagement feature avoids harsh take up of drive when selecting Drive or Reverse. This is
achieved by limiting engine speed and engine torque which results in a rapid, but progressive
engagement of either Drive or Reverse when moving from the Park or Neutral positions. Drive and
Reverse engagements from either Park or Neutral are performed in less than 2.2 seconds. There is no
drive engagement prevention strategy implemented on the transaxle system as there is sufficient engine
strategy to protect the system. However, reverse engagement is prevented until vehicle speed is less
than 7 km/h.
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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.
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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.
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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 -
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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.
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 -
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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.
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6. CAN NETWORK
The TCU sends signals to be used by other vehicle systems via the CAN bus, such as:
Selector lever position
Selected gear state
Manual mode activation
Transaxle fluid temperature
Engine torque reduction requests -
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Schematic Diagram of Network Communication
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3190-01
2. TIGHTENING TORQUE
Part name Tightening torque Remark
1. Drive gear mounting bolt of differential carrier 166.6 to 176.4 Nm 10 EA
2. Reverse shaft mounting bolt 74.5 to 89.2 Nm
3. Transmission case mounting bolt 19.6 to 26.5 Nm 22 EA
4. Concentric slave cylinder mounting bolt 11.8 to 14.7 Nm 3 EA
5. Backup lamp switch 29.4 to 34.3 Nm
6. Neutral switch 29.4 to 34.3 Nm
7. Oil filler plug 58.8 to 78.4 Nm
8. Oil drain plug 58.8 to 78.4 Nm
9. Oil plug 58.8 to 78.4 Nm
10. Shift lever mounting nut 42.2 to 53.9 Nm
11. Selector lever mounting nut 42.2 to 53.9 Nm
12. Control shaft assembly mounting bolt 9.8 to 11.8 Nm 7 EA
13. Guide bolt 42.2 to 53.9 Nm
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Front view Rear view
1. OVERVIEW
This vehicle is equipped with WM6F1 M/T (Manual Transmission). This transmission is integrated with an
axle and designed to maximize the driving performance by optimizing the gear ratio according to the
engine torque.
WM6F1 M/T assembly