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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
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3660-01
The shiftable gear can be adjusted by pressing the
"UP (D+)" or "DOWN(D-)" switch when the gear
Shift lock release button
If the selector lever cannot be moved from
while pushing down this button with finger. For
safety, turn off the engine and depress the
brake pedal before the attempt.Shift up Shift down Tip switches on steering wheel
Meter cluster
This indicator shows the current position of
the gear.
Gear selector lever
Lever positions
P : Park
R : reverse
N : Neutral
D : DriveTip switch (manual shift switch)
The shiftable gear can be adjusted by
moving this switch to forward and rearward
position.
Selection of Manual/Automatic Shift Function
D: Automatic shift according to the driving condition
M: Manual shift
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4. COMPONENTS
HPT 6A/T (6F24)
One-way clutchTorque converter
(with slip lockup)
Oil pumpHarness
Valve bodySide gearDriven gear
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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.
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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2) Operation in Each Gear Position
(1) Neutral/Park
REAR) P/C locked
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Power flow
Description 35R C OD C 26 B UD B LR B O.W.C
P.N
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(2) Reverse (3.385)
Middle planetary gear locked, middle sun gear rotated
When the sun gear rotates with the planetary gear locked in middle planetary gear set, the annulus
gear (front planetary gear) rotates in reverse direction with decreased speed and the power flows
through the front planetary gear.
The rear planetary gear set reduces the rotating speed of rear & front annulus gears and the front
planetary gear set rotates the front sun gear in reverse direction without load. -
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Power flow
Description 35R C OD C 26 B UD B LR B O.W.C
R
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(3) 1st Drive Gear (4.212)
Front sun gear and middle & rear planetary gears locked, and rear sun gear always rotated
When the rear sun gear rotates, the rear planetary gear set reduces the speed at first, and then the
reduced power is transferred to rear & front annulus gear. The power is secondarily reduced at front
planetary gear locked with sun gear and flows to front planetary gear.
At this moment, the middle sun gear rotates in reverse direction without load (idling) by the rotation of
middle annulus gear integrated with front planetary gear. -
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Power flow
Description 35R C OD C 26 B UD B LR B O.W.C
1ST
Operated below 5 km/h of vehicle speed O :