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Frelander 2. Manual - part 320

Automatic Transmission/Transaxle - Transmission Description

Description and Operation

COMPONENT LOCATION

Item

Part Number

Description

Transmission selector lever assembly

Cable bracket

Automatic transmission

Transmission Control Module (TCM)

Lever arm

Transmission fluid cooler

OVERVIEW

The AW F21 automatic transmission is a 6 speed, electronically controlled unit manufactured by Aisin AW in Japan. The
transmission represents the latest in automatic transmission technology for a transverse, All Wheel Drive (AWD) unit. The
transmission features lock-up slip control, 'CommandShift™' functions and automatic and driver selectable modes to give
the optimum on and off road performance.

The transmission is controlled by a TCM which contains software to provide operation as a semi-automatic
'CommandShift™' transmission. The TCM allows the transmission to be operated as a conventional automatic unit by
selecting P, R, N, D on the selector lever. Movement of the selector lever across the gate to the 'M/S' position puts the
transmission into electronic 'Sport' mode. Further movement of the lever in a longitudinal direction to the + or – position

puts the transmission into electronic manual 'CommandShift™' mode.
For additional information, refer to:

External Controls

(307-05 Automatic Transmission/Transaxle External Controls,

Description and Operation).

The AW F21 transmission has the following features:

Designed to be maintenance free
Torque capacity of 450 Nm
Transmission fluid is fill for life
The torque converter features a controlled slip feature with electronically regulated lock-up control on gears 2 to 6
Shift programs controlled by the TCM
TCM has an adaptive capability to ensure efficient gear shift quality throughout the service life of the transmission
Diagnostics available from the TCM via the high speed Controller Area Network (CAN) bus.

TRANSMISSION

The transmission comprises the main casing which houses all of the transmission components. The torque converter is
located in a separate converter housing.

AW F21 Automatic Transmission - Sectional View

Item

Part Number

Description

Clutch - C2

Brake - B2

One-way clutch - F1

Clutch - C1

Brake - B1

Clutch - C3

Torque converter

Fluid pump

Differential assembly

Counter driven gear

Counter drive gear

The main casing retains the fluid at the bottom. A combined drain/filler plug is located in the bottom of the casing. The oil
level is checked by removing the inner fill plug when the transmission fluid is at a temperature of between 50 to 60°C (122
to 140°F). W hen the oil flow becomes a drip from the plug hole, the level is correct.

The transmission has a fluid cooler which is located on the Left Hand (LH) end of the radiator. The cooler is connected to
the transmission converter housing by 2 pipes. The fluid cooler is connected into the engine cooling system and cools the
transmission fluid by heat transfer through the cooler to the engine coolant.
For additional information, refer to:

Transmission Cooling

(307-02 Transmission/Transaxle Cooling, Description and

Operation).

TORQUE CONVERTER

Item

Part Number

Description

Torque converter housing

Lock-up clutch

Turbine

Impeller

Stator

Fluid pump

Input shaft

The torque converter is the coupling element between the engine and the transmission and is located in the transmission
housing, on the engine side of the transmission. The driven power from the engine crankshaft is transmitted hydraulically
and mechanically through the torque converter to the transmission. The torque converter is connected to the engine by a
drive plate.

The torque converter comprises an impeller, a stator and a turbine. The torque converter is a sealed unit with all
components located between the converter housing cover and the impeller. The two components are welded together to
form a sealed, fluid filled housing. W ith the impeller welded to the converter housing cover, the impeller is therefore
driven at engine crankshaft speed.

The torque converter contains a hydraulically operated lock-up clutch which is controlled by the TCM via a solenoid in the
valve block which actuates spool valves to control the hydraulic pressure applied to the clutch. This allows the TCM to
provide 3 modes of converter operation; unlocked, partially locked and fully locked.

VALVE BLOCK

The valve block is located in a vertical position at the front of the transmission main casing, behind a sealed cover. The
valve block contains a number of solenoids, dampers and spool valves to control the transmission operation. The solenoids
are controlled by the TCM to provide gear changes and smooth transition between ratio changes.

Solenoids

Item

Part Number

Description

3-W ay solenoid - S1

3-W ay solenoid - S2

Line pressure control solenoid - SLT

Shift control solenoid - SLC2

Shift control solenoid - SLC1

Lock-up control solenoid - SLU

Shift control solenoid - SLC3

Shift control solenoid - SLB1

Valve block

Shift Control Solenoids - SLC1, SLC2, SLC3, SLB1

The shift control solenoids (SLC1, SLC2, SLC3 and SLB1) are installed on the front valve body. The solenoids respond to
inputs from the TCM and control the hydraulic pressure applied to the clutches (C1, C2 and C3) and to the brake B1 to
provide smooth shifting. The TCM uses a single or a combination of these solenoids to provide shifts from 1st to 6th gear.

If a solenoid fails, the TCM will remove the current to the shift control solenoids and the transmission will use limp home
mode, to prevent damage to the transmission.

Line Pressure Control Solenoid - SLT

The line pressure control solenoid (SLT) is installed on the front valve body. The solenoid is controlled in a linear manner
by the TCM which uses throttle opening degree signals and engine torque information from the Engine Control Module
(ECM) to determine the solenoid operation. The solenoid controls the line pressure applied to the clutches and brakes to
provide smooth shifting.

If the solenoid fails, the TCM will remove the current supplied to the solenoid. Maximum line pressure will be applied to
the clutches and brakes unless the failure is due to the solenoid valve sticking, which may result in low line pressure.

Lock-Up Control Solenoid - SLU

The lock-up control solenoid is installed on the front valve body. The solenoid is controlled in a linear manner by the TCM
which uses engine speed, throttle opening degree signals and transmission speed sensor signals to determine the
solenoid operation. The solenoid controls the amount of lock-up or slip required for the torque converter lock-up clutch.

If the solenoid fails, the TCM removes the current supplied to the solenoid which results in no torque converter lock-up
being applied.

3-W ay Solenoid - S1, S2

The 3-way solenoid (S1) is located on the center valve body and solenoid (S2) is located on the front valve body. The
solenoids are on/off solenoids controlled by the TCM. A combination of the 2 solenoids is used to operate either the 1st
gear engine braking or enable gear shifts.

If a solenoid fails, the TCM will remove the current supplied to both solenoids.

Speed Sensors

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