Mechanism & Function -- Automatic Transmission (5AT): Other Subaru Outback BP рестайлинг

General

To improve the dynamic performance and fuel efficiency of the vehicle, a new 5-speed automatic transmission is developed. The features of this new automatic transmission are as follows

NEW CONSTRUCTION

1. The planetary gears layout has been changed from the conventional 2-planetary to a 3-planetary arrangement.
2. The construction of the torque converter has been changed to achieve a higher efficiency.
3. The layout of the oil pump has been changed to reduce friction.
4. The drive pinion gear has been changed.
5. Major components are made of aluminum.

IMPROVED SHIFTING PERFORMANCE

1. By using a wide ranged and crossed ratio gears, a high driving power is ensured at a wide vehicle speed range, and the torque differential between before and after shifting is minimized.
2. By using a system that controls the clutch pressure directly and electronically (direct hydraulic control), an accurate and highly responsive control is achieved.
3. By using a one-way clutch, smooth shifting without torque interruption is realized.
4. By using a new adaptive control, the shifting map is automatically switched and a more active shifting control is performed in the manual mode.
5. The control enables manual shifting by operating the steering switch to UP or DOWN while driving in D range, and returns to normal automatic shifting when certain conditions are met.
6. To reduce gear noise from the reduction driven gear and prevent the bending moment of the drive pinion shaft from affecting the engagement of reduction gears, the front and rear ends are supported with bearings.
7. To reduce driving noise, the drive shafts and joints are integrated and the transmission side drive axle shaft is abolished.

OPTIMIZED GEAR RATIO

1. The wider gear ratio range obtained by five speeds contribute to better dynamic performance, while improving fuel efficiency at constant speed cruising by enabling use of lower engine speeds.

IMPROVED EFFICIENCY

1. The efficiency of the torque converter has been increased.
2. Friction in the oil pump and gear train are reduced.
3. Drive pinion gear teeth are changed to uniform height teeth, and their offset amount is reduced.
4. Ranges in which the transmission operates in slipping lockup and full lockup states are widened.

WEIGHT REDUCTION

1. An aluminum bearing plate is used.
2. The planetary carrier, clutch drum and the hub are made of aluminum.
3. The wall thickness of the transmission case is reduced.

CONVENTIONAL MECHANISMS

1. The transfer is provided with a VTD (Variable Torque Distribution) system which consists of a planetary gear type center differential and a hydraulic multi-plated LSD, to electronically control the differential operation and improve safety and drivability.

Scheme 59

CONSTRUCTION

The pump consists of a inner-teeth type rotor, oil pump housing, and an oil pump cover. The inner rotor has nine teeth and the outer rotor has ten teeth.

Scheme 60

The front brake consists of a front brake piston, return spring, drive plates, driven plates, and a retaining plate.

This brake engages to lock the front sun gear when engine braking is used in the 1st, 2nd and 3rd speeds and in the 5th speed and reverse range.

Scheme 61

The input clutch consists of an input clutch piston, retainer spring, drive plates, driven plates, and a retaining plate.

This clutch engages to connect the front internal gear and mid internal gear in the 4th and 5th speeds.

Scheme 62

The direct clutch consists of a direct clutch piston, retainer spring, drive plates, driven plates, and a retaining plate.

This clutch engages to connect the rear carrier and rear sun gear in the 2nd, 3rd and 4th speeds.

(The direct clutch cannot be disassembled.)

Scheme 63

The high and low reverse clutch consists of a high and low reverse clutch piston, retainer spring, drive plate, driven plate, and a retaining plate.

This clutch engages to fix the mid sun gear with the rear sun gear in the 3rd, 4th and 5th speeds.

It also fix the mid sun gear and rear sun gear when engine braking is used in 1st speed.

In reverse, the mid sun gear and rear sun gear are connected.

(The high & low reverse clutch cannot be disassembled.)

Scheme 64

The reverse brake which consists of a reverse brake piston, return spring, dish plate, drive plates, driven plates and retaining plate, is placed in a housing formed in the transmission case.

This brake fixes the rear carrier in reverse range.

Scheme 65

The forward brake consists of a forward brake hub, forward brake piston, dish plate, drive plates, driven plates, and a retaining plate.

The forward brake restricts the reverse rotation of the mid sun gear in 1st and 2nd speeds.

(The forward brake cannot be disassembled.)

Scheme 66

The low coast brake consists of a low coast brake hub, low coast piston, drive plates, driven plates, and a retaining plate.

The low coast brake restricts the reverse rotation of the mid sun gear when engine braking is used in 1st and 2nd speeds of the manual mode.

(The low coast brake cannot be disassembled.)

Scheme 67

Control Valve

The control system of the automatic transmission consists of an oil pump, valve bodies containing valves, clutches, and fluid passages. The operation of the system is controlled by driver's manual inputs and electrical inputs from the TCM.

CONTROL VALVE FUNCTION CHART

Scheme 68

The gear train consists of three sets of planetary gears, three sets of multi-plate clutches, four sets of multi-plate brakes and three set of one-way clutches.

Scheme 69

Scheme 70

N RANGE

Since the forward and reverse brakes are disengaged, driving power from the input shaft is not transmitted to the output shaft.

P RANGE

1. Since the forward and reverse brakes are disengaged as in the N range, driving power from the input shaft is not transmitted to the output shaft.
2. The parking pawl, which is linked with the selector lever engages with the parking gear and mechanically holds the output shaft.

Scheme 71

1st SPEED GEAR OF D RANGE

1. The forward brake and forward one-way clutch operates to control the reverse rotation of the mid sun gear.
2. The 1st one-way clutch operates to control the reverse rotation of the rear sun gear.
3. The 3rd one-way clutch operates to control the reverse rotation of the front sun gear.
4. As the mid sun gear spins during deceleration, the forward one-way clutch spins and engine braking effect will not be available.

Scheme 72

1st SPEED GEAR OF MANUAL MODE

1. The front brake operates to hold the front sun gear.
2. The forward brake and forward one-way clutch operates to control the reverse rotation of the mid sun gear.
3. The high and low reverse clutch operates to engage the rear sun gear and the mid sun gear.
4. The low coast brake operates to hold the mid sun gear.
5. During deceleration, the low coast brake controls the reverse rotation of the mid sun gear and engine braking effect will be available.

Scheme 73

2nd SPEED GEAR OF D RANGE

1. The forward brake and forward one-way clutch operates to control the reverse rotation of the mid sun gear.
2. The 3rd one-way clutch operates to control the reverse rotation of the front sun gear.
3. The direct clutch engages to connect the rear carrier and rear sun gear.
4. As the mid sun gear spins during deceleration, the forward one-way clutch spins and engine braking effect will not be available.

Scheme 74

2nd SPEED GEAR OF MANUAL MODE

1. The front brake operates to hold the front sun gear.
2. The forward brake and forward one-way clutch operates to control the reverse rotation of the mid sun gear.
3. The direct clutch engages to connect the rear carrier and rear sun gear.
4. The low coast brake operates to hold the mid sun gear.
5. During deceleration, the low coast brake controls the reverse rotation of the mid sun gear and engine braking effect will be available.

Scheme 75

3rd SPEED GEAR OF D RANGE OR MANUAL MODE

1. The front brake operates to hold the front sun gear.
2. The direct clutch engages to connect the rear carrier and rear sun gear.
3. The high and low reverse clutch engages to connect the mid sun gear and rear sun gear.

Scheme 76

4th SPEED GEAR OF D RANGE OR MANUAL MODE

1. The direct clutch engages to connect the rear carrier and rear sun gear.
2. The high and low reverse clutch engages to connect the mid sun gear and rear sun gear.
3. The input clutch engages to connect the front internal gear and mid internal gear.
4. Drive power is transmitted to the front internal gear, mid internal gear and rear carrier; the three planetary gears turn together as a unit in the normal direction.

Scheme 77

5th SPEED GEAR OF D RANGE OR MANUAL MODE

1. The front brake operates to hold the front sun gear.
2. The input clutch engages to connect the front internal gear and mid internal gear.
3. The high and low reverse clutch engages to connect the mid sun gear and rear sun gear.

Scheme 78

R RANGE

1. The front brake operates to hold the front sun gear.
2. The high and low reverse clutch engages to connect the mid sun gear and rear sun gear.
3. The reverse brake operates to hold the rear carrier.

Scheme 79

Used in the transfer is the VTD (Variable Torque Distribution) system which combines a compound planetary gear type center differential installed in the transfer case behind the transmission and a hydraulically operated multi-plate differential action limiting device (LSD) located between the output shafts of the center differential. Differential action limiting control is performed by the TCM according to driving and road surface conditions.

The input torque is transmitted to the 1st sun gear of the center differential through the intermediate shaft. From the 1st sun gear, the torque is transmitted through the 1st pinion to the output carrier in the front wheel output shaft, and through the 2nd pinion to the 2nd sun gear in the rear wheel output shaft.

The center differential performs the differential functions of absorbing the speed difference between the front and rear wheels and also distributes drive forces to the front and rear wheels at a predetermined ratio. In normal conditions (when pressure is not applied to the multi-plate clutch), the drive force distribution ratio is 45.7 % to the front wheels and 54.3 % to the rear wheels. The hydraulic multi-plate clutch connected in parallel with the center differential between the carrier and 2nd sun gear functions as a differential action limiting device (LSD) and also as a device that controls torque distribution according to driving conditions.

Differential action limiting control is performed as a "torque responsive control", where control is based on the input torque to the transfer as calculated from the engine torque, torque converter characteristics, gear ratio, etc. The LSD clutch is controlled by the hydraulic pressure regulated by the transfer valve in the transmission hydraulic control valve assembly, as a result of the TCM directly controlling the linear solenoid. The torque distribution ratio to front and rear wheels changes from 45.7:54.3 to direct connection, in accordance with the hydraulic pressure acting on the pistion.

The speed of the front and rear wheels determine the basic signals for the differential action limiting control. The rear wheel speed is detected by the sensor installed above the rear drive shaft, and the front wheel speed is detected by the sensor on the parking gear above the reduction gear.

MULTI-PLATE CLUTCH (LSD)

The transfer's differential action limiting device (LSD) consists of a piston that press together the wet multi-plate clutch to generate differential action limiting force.

The rear drive shaft has drilled oil passages for lubrication of multi-plate clutch and extension bushing and ball bearing in it.

Scheme 80

TRANSFER HYDRAULIC PRESSURE CONTROL UNIT

The transfer hydraulic control unit consists of the transfer linear solenoid installed in the transmission hydraulic control valve assembly and the transmission hydraulic control valve.

The transfer linear solenoid controls the transfer pilot pressure in accordance with the differential action limiting force determined by the TCM based on driving and road conditions, and the transfer hydraulic control valve regulates the line pressure into transfer pressure in accordance with the transfer pilot pressure.

The transfer pressure is sent through the passages formed in the transmission case and extension case to the clutch piston chamber.

CONTROL ITEMS

CONTROL ITEMS DESCRIPTION CHART

CONTROL OF HYDRAULIC PRESSURE FOR SHIFTS

1. Control of linear solenoid for each shift clutch The linear solenoid for each shift clutch is directly controlled by means of electrical current in accordance with the target gear speed. The control current value is corrected any time when necessary by the learning control and real time feedback functions to improve shift quality and eliminate errors due to aging.
2. Engine braking control In manual mode, the low coast brake solenoid is controlled to make engine braking available in 1st and 2nd speeds.

LOCKUP CONTROL

1. By engaging the lockup clutch in the torque converter, the slip in the torque converter is eliminated and power is transmitted more effectively.
2. Based on signals from the TCM, the lockup solenoid is controlled in order to let the lockup control valve operate and adjust apply pressure/release pressure, to consequently vary the lockup clutch engagement force.

Lockup operation conditions

Scheme 81

Scheme 82

LOCKUP DISENGAGED STATE

When lockup is disengaged, the lockup solenoid causes the lockup control valve to open the clutch disengaging port, and the lockup operating pressure is added to the disengaging circuit. In the meantime, the lockup clutch control valve opens the lockup clutch engaging port and allows the hydraulic fluid in the circuit to flow to the ATF cooler, thus lowering the pressure in the engaging circuit. As a result, the lockup clutch is disengaged due to difference in pressure between both circuits. This operation is performed in all speed gears.

LOCKUP ENGAGED STATE

When lockup is engaged, the lockup solenoid puts the lockup control valve in the lockup state and builds up lockup operating pressure.

The lockup control valve then opens the clutch engaging circuit's port that communicates to the torque converter's impeller chamber, allowing high pressure fluid to flow to the lockup clutch and the clutch is engaged.

This operation is performed in all speed gears, and the lockup engages in response to the vehicle speed when the 5th gear is selected in the D range.

SMOOTH LOCKUP CONTROL

During the transition period from the lockup (disengaged) state to the lockup engaged state, the TCM controls the current output to the lockup solenoid. By changing the current output to the lockup solenoid and gradually raising the lockup clutch pressure, the lockup clutch piston is first put in a partially engaged state and its pressure is gradually increased to reduce shock.

LINE PRESSURE CONTROL

When torque signals corresponding to the engine drive power is sent from the ECM to the TCM, the TCM controls the line pressure solenoid. Using the line pressure solenoid pressure as a signal pressure, the pressure regulator valve is controlled, and the ATF discharged from the oil pump is regulated to an optimum level corresponding to the vehicle's running conditions.

Scheme 83

LINE PRESSURE CONTROL IN NORMAL CONDITIONS

The line pressure which engages shift clutches to create 1st to 4th speeds, is regulated to a pressure required at each clutch according to the input torque.

Scheme 84

LINE-PRESSURE CONTROL DURING ENGINE BRAKING IN SPORTS MODE

When engine braking is used to let the transmission downshift, the line pressure is regulated in accordance with the vehicle speed.

Scheme 85

LINE-PRESSURE CONTROL DURING SHIFTING

During shifting, the line pressure is set to a level suitable for the input speed, input torque and the difference between the required and current gear speed.

Scheme 86

LINE PRESSURE CONTROL WHEN ATF TEMPERATURE IS LOW

When the ATF temperature is low, the line pressure control characteristics is set higher than normal so that the clutches and brakes will operate at an earlier stage.

Scheme 87

REAR VEHICLE SPEED SENSOR

This vehicle speed sensor is a Hall element type sensor and is externally mounted on the extension case. It detects the rear wheel speed in terms of the peripheral speed of the rear drive shaft and sends pulse signals (22 pulses per rotation) to the TCM.

Scheme 88

FRONT VEHICLE SPEED SENSOR

This vehicle speed sensor is a Hall element type sensor and is mounted on the inside of the transmission case. It detects the drive pinion shaft speed and sends pulse signals (16 pulses per rotation) to the TCM.

Signals from the front and rear vehicle speed sensors are used to calculate controlling vehicle speed, which is in turn used for gear shift control.

Scheme 89

ATF TEMPERATURE SENSOR 1,2

These temperature sensors are thermistors and each of them is mounted on the control valve body. ATF temperature sensor 1 detects the ATF temperature in the oil pan, and ATF temperature sensor 2 detects the ATF temperature at the torque converter outlet; each sensor outputs electrical resistance signals.

Scheme 90

TURBINE SPEED SENSOR 1, 2

Wheel speed sensors are hall element type sensors. Turbine speed sensor 1 detects the speed of the front sun gear, and turbine sensor 2 detects the speed of the front carrier. Each sensor sends pulse signals (60 pulses per rotation) to the TCM. From these two speed values, the TCM calculates the turbine speed and uses it for shifting control.

Scheme 91

INHIBITOR SWITCH

The inhibitor switch is installed in the control valve and is connected to the TCM with 4 signal lines. The TCM uses this signal to detect range positions and to perform various controls. Relation between signals from the 4 lines (INH1 to 4) and range positions are as shown below

INHIBITOR SWITCH SPECIFICATION CHART

When the range position is detected as P or N as shown above, the TCM sends a signal (PN signal) allowing operation of the starter. On the other hand, in R or D range, starter operation is inhibited to ensure safety.

Additionally, when the range position is detected as R, the TCM turns the backup light relay output to ON and lets the backup lights illuminate.

Scheme 92

LINE PRESSURE SOLENOID

The line pressure solenoid is mounted on the control valve and is directly controlled by electrical current instructions from the TCM. This controls the pressure modifier valve and accumulator control valve A to adjust the line pressure to an optimum pressure level suitable for operating conditions.

Scheme 93

LOCKUP SOLENOID

The lockup solenoid is mounted on the control valve and is directly controlled by electrical current instructions from the TCM. It then controls the lockup control valve to provide smooth engagement and disengagement. It also enables stable slip lockup control while supported by learning control and real time feedback functions.

Scheme 94

FRONT BRAKE SOLENOID

The front brake solenoid is mounted on the control valve and is directly controlled by electrical current instructions from the TCM. This solenoid is activated when the front brake is to be engaged. Control values are corrected any time when necessary by the learning control and real time feedback functions to improve shift quality and eliminate errors due to aging.

Scheme 95

INPUT CLUTCH SOLENOID

The input clutch solenoid is mounted on the control valve and is directly controlled by electrical current instructions from the TCM. This solenoid is activated when the input clutch is to be engaged. Control values are corrected any time when necessary by the learning control and real time feedback functions to improve shift quality and eliminate errors due to aging.

Scheme 96

DIRECT CLUTCH SOLENOID

The direct clutch solenoid is mounted on the control valve and is directly controlled by electrical current instructions from the TCM. This solenoid is activated when the direct clutch is to be engaged. Control values are corrected any time when necessary by the learning control and real time feedback functions to improve shift quality and eliminate errors due to aging.

The direct clutch pressure can be switched to two range pressures with the direct clutch piston switch valve.

Scheme 97

HIGH AND LOW REVERSE CLUTCH SOLENOID

The high and low reverse clutch solenoid is mounted on the control valve and is directly controlled by electrical current instructions from the TCM. This solenoid is activated when the high and low reverse clutch is to be engaged. Control values are corrected any time when necessary by the learning control and real time feedback functions to improve shift quality and eliminate errors due to aging.

Scheme 98

LOW COAST BRAKE SOLENOID

The low coast brake solenoid is mounted on the control valve and is directly controlled by ON/OFF instructions from the TCM. This solenoid is activated when the low coast brake is to be engaged during usage of engine braking in 1st or 2nd speed in manual mode.

Scheme 99

TRANSFER SOLENOID

The transfer solenoid is mounted on the control valve and is directly controlled by electrical current instructions from the TCM. This ensures optimum AWD control in accordance with the varying road conditions by engaging/releasing the transfer clutch.

Scheme 100

MEMORY BOX

The memory box is mounted on the control valve and stores hydraulic correction values and learned values for the initial shifting pressures for each solenoid, based on its hydraulic characteristics at the time delivered from the factory. The TCM acquires data from this memory box and performs correction based on these data to control each solenoid. This ensures high quality shifting from the time the vehicle was delivered from the factory.

Scheme 101

Transmission Control Module (TCM)

The TCM receives various sensor signals and determines the running conditions of the vehicle. It then sends control signals to each solenoid according to the preset gearshift characteristic data, lockup operation data, and transfer clutch torque data.

CONTROL SYSTEM

INPUT SIGNALS REFERENCE

Scheme 102

ORDINARY SHIFT CONTROL

The TCM controls each solenoid based on input signal information such as inhibitor switch signals, vehicle speed signals and accelerator pedal position signals, to automatically select the optimum gear position from the shifting map.

ENGINE COOPERATIVE CONTROL

During shifting, the TCM outputs a torque-down requirement signal, and the ECM receives this to retard the ignition timing of each cylinder to temporary decrease the output torque from the engine. Simultaneously with this control, the TCM constantly monitors the shift sequence through vehicle speed sensors and the turbine speed sensor to perform feedback control and optimize gear shifts. Because of this control, a smooth and comfortable gear shifting is ensured under all conditions.

ABS COOPERATIVE CONTROL

When the ABS is operating, the optimum gear speed for the vehicle speed is selected by cooperative operation with the ABSCM to prevent degrading the operation of the ABS.

CONTROL AT HIGH OIL TEMPERATURES

If the ATF temperature becomes extremely high, shifting control is performed by automatically switching to a shifting map that is less likely to cause temperature rise.

CONTROL WHEN ATF OR ENGINE COOLANT TEMPERATURE IS LOW

When the ATF temperature or engine coolant temperature is extremely low at engine start, etc., shifting control is performed by automatically switching to a shifting map that causes temperature rise easier.

ADAPTIVE CONTROL

This control is performed to improve the drivability of the vehicle by optimizing gear shifts in accordance with the driver's intention to accelerate or decelerate, and driving conditions such as hill climbing, winding road driving, etc.

Scheme 103

Scheme 104

1. Shift pattern automatic switching control This control enables selection of the optimum gear speed by automatically switching the shift pattern by estimating driver's intentions and driving conditions through sensor information such as driving resistance, engine speed, acceleration, vehicle speed, and also from calculated values. Any of the three patterns NORMAL, SPORTS, and SLOPE are continuously and automatically selected under the following conditions. D range NORMAL, SPORTS, SLOPE D range, in sports mode SPORTS, SLOPE Normal pattern: covers a wide range from normal driving to high speed driving. Sports pattern: a shift pattern suitable for driving conditions requiring deep accelerator pedal positions, such as winding road driving. Slope pattern: this shift pattern controls upshifting to prevent too frequent gear shifting during climbing or descending hills. By combining braking control (in sports mode only) (explained later), automatic engine braking will be available when descending hills.
2. Accelerator pedal quick depressing control When the accelerator pedal is quickly depressed, the TCM interprets this as acceleration is required, and the transmission is downshifted earlier to obtain a greater drive force.
3. Accelerator pedal quick return control When the accelerator pedal is quickly released, the TCM interprets this as deceleration is required, and upshift is prohibited in order to hold the transmission in the current gear speed to prevent frequent shifting and to maintain engine braking effect (operates in sports mode only).
4. Braking control According to the braking force (deceleration) during braking, downshifts are hastened to ensure engine braking effect and obtain a larger driving power for accelerating after braking (operates in sports mode only).
5. Control during cornering When the system interprets that the vehicle is turning a corner by the lateral acceleration and the change rate in vehicle speed, it prevents unwanted upshifts to maintain a stable drive force and cornering performance.

SPORTS MODE CONTROL

When the shift lever is moved toward the manual gate side in D range, the SPORT light in the combination meter illuminates and the system enters the Sports mode. Gearshift timings are set at higher vehicle and engine speeds to make more use of low speed gears. The full lockup vehicle speed in 5th is also set higher than in the normal mode.

MANUAL MODE CONTROL

By operating the "+" or "-" switch on the select lever or steering wheel in D range with the sports mode switch ON (in sports mode), the system switches to manual mode. In this mode, operating the "+" switch causes upshifting while operating the "-" switch causes downshifting; manual shifting is enabled and the selected gear position is held while driving.

However, at certain vehicle speeds or ATF temperatures, the following inhibiting control is performed.

1. Upshift inhibiting and auto downshift control The gear upshifts each time the "+" switch is operated, however, when the vehicle speed is too low for the selected gear speed, the TCM inhibits further upshifting. If the vehicle speed becomes too slow for the current gear speed, a downshift will be made automatically to prevent engine stall. When the vehicle comes to a stop, the transmission will always be controlled to shift to 1st speed unless the vehicle was in manual 2nd hold control.
2. Downshift inhibiting control The gear downshifts each time the "-" switch is operated, however, when the vehicle speed is too low for the selected gear speed, the TCM inhibits further shifting. A manual shifting inhibiting buzzer will sound to warn the driver.
3. Control when oil temperature is low When the ATF temperature is low as in cases such as immediately after start in winter, upshifting to 5th is inhibited to quicken warm up.
4. Engine over speed prevention control If the engine speed exceeds the preset value during accelerating, the fuel supply is cut to prevent over-revving of the engine.

2nd HOLD CONTROL (IN MANUAL MODE)

When the "+" switch is operated when the vehicle is in manual mode and not moving, the transmission shifts to 2nd speed enabling start in 2nd. This status is held unless the manual mode is canceled, or a speed other than 2nd is selected with the "-" switch. Also, the transmission is held in 2nd when the vehicle is stopped.

STEERING SPORTS SHIFT CONTROL

By operating the "+" or "-" switch on the steering wheel in D range during Normal mode, the system can be temporary switched to manual mode to perform manual shift operations. In this mode, the mode automatically returns to the previous mode when the next operation is not performed within a specified time or when the vehicle is put in the straight forward accelerating state.

Scheme 105

ILLUMINATION CONTROL OF VARIOUS INDICATORS

Illuminations of the various indicators on the combination meter are controlled in accordance with the shift pattern selection as shown below.

Scheme 106

CONTROL VALVE HYDRAULIC PRESSURE CORRECTION CONTROL AND LEARNING CONTROL

1. Control valve hydraulic pressure correction control During this control, the TCM acquires the hydraulic pressure correction data stored for each control valve in the memory box installed on the control valves, and then correctively controls the instruction current to each solenoid based on the data. This ensures stable shifting quality irrespective of variance between units.
2. Learning control of shifting hydraulic pressures To constantly ensure excellent shift quality regardless of the variance between friction material and aging, learning control of shifting hydraulic pressures is used. Learning takes place for every normal shifting under certain conditions, and the learned values are saved in the flash ROM of the TCM. The values are not cleared even when the power is turned OFF (or the battery's negative terminal disconnected).

NORMAL CONTROL

The input torque to the multi-plate clutch is calculated according to various factors such as engine torque signals, torque converter turbine speed and selected gear position. Based on the calculation result, the basic coupling force of the clutch is determined.

START CONTROL

When the vehicle speed is 0 km/h (0 MPH), the TCM increases the engaging force of the multi-plate clutch to a higher level compared to that of normal control.

This enables the vehicle to start smoothly without swerving even on a slippery road.

TURNING CONTROL

The TCM makes a correction such that the engagement force of the multi-plate clutch is reduced as the steering angle increases.

This function is performed to improve turning performance at certain vehicle speed range.

SLIP CONTROL

When front or rear wheels start slipping with the vehicle running slower than the predetermined speed, the TCM makes control to increase the differential action limiting torque.

This function maintains traction and improves driving stability.

Scheme 107

ABS CONTROL

When the TCM receives an ABS operation signal from the ABSCM, it adjusts the differential action limiting torque to the predetermined level.

This function improves ABS control.

BASE BRAKE CONTROL

When the brake switch is ON and the throttle valve is fully closed, the TCM makes control to decrease the differential action limiting torque. The ABS control has priority over this control.

This function improves stability during braking.

RANGE LOCK CONTROL

This control prevents the select lever from being moved to the R position when the vehicle is running. Thus damage to components such as the reverse clutch is prevented.

When the specified speed is exceeded the TCM turns off the shift lock solenoid for the select lever. Therefore the range lock control works to inhibit operation from N range to R range, preventing the transmission from put into reverse.

1. The on-board diagnosis system detects and indicates a fault by generating a code corresponding to each fault location. The engine malfunction indicator light (SPORTS indicator light) on the combination meter indicates occurrence of a fault or abnormality.
2. When the engine malfunction indicator light comes on as a result of detection of a fault by the TCM, the corresponding diagnostic trouble code (DTC) is stored in the TCM.
3. On OBD-II available vehicles, it is necessary to connect the SUBARU Select Monitor (SSM) to the data link connector in order to check the DTC.
4. To provide various functions and to facilitate fault isolation, a diagnosis system compatible with the SSM is used.
5. The on-board diagnostics system detects the following electrical system faults or abnormalities in the system.

ATF TEMPERATURE SENSOR REFERENCE

If a fault is detected, the system tells the fault by causing the SPORTS indicator light to blink.

Fail-safe Function

1. Front and rear vehicle speed sensors, rear wheel speed sensor abnormal If a fault is detected in either or both of the front vehicle speed sensor and rear vehicle speed sensor, the vehicle speed information received from the ABS unit via CAN communication is substituted for control. This enables normal quality shifting.
2. Inhibitor switch abnormal If an input of other than the specified pattern is entered to the TCM, the select position indicator lights in the combination meter are turned off, the starter is disabled, the reverse light is disabled, the transmission is fixed in D range, and manual mode is inhibited.
3. PN signal abnormal The output is turned OFF (starter inhibited) if an abnormality is detected in the PN signal output. However, if the ECM is receiving range signals through the backup of CAN communication, the starter can be used in P and N ranges.
4. AT interlock decision If an AT interlock decision is made, the vehicle's minimum mobility is maintained by fixing the transmission in 2nd, 4th or 5th speeds in accordance with the engaging pattern detected by the hydraulic switch. Relation between the hydraulic switch detection pattern and fixed gear speeds are as shown in the following table.
5. Engine braking in 1st abnormal decision If 1st engine braking abnormal decision is made, the low coast brake solenoid is deactivated to cancel the engine braking effect.
6. Line pressure solenoid abnormal The solenoid is deactivated and the line pressure set at maximum, 5th speed is inhibited. Except for this, the system is controlled normally.
7. Lockup solenoid abnormal The solenoid is deactivated and lockup is inhibited.
8. Low coast brake solenoid abnormal If the solenoid is failed and stuck in its ON state (electrically or mechanically) the transmission is fixed in 2nd speed, and when the solenoid is failed and stuck in its OFF state (electrically or mechanically) the solenoid is constantly turned OFF. (Engine braking is made not available in 1st and 2nd speeds.)
9. Input clutch solenoid abnormal If the solenoid is failed and stuck in its ON or OFF state (electrically or mechanically) the transmission is fixed in 4th speed to maintain mobility.
10. Direct clutch solenoid abnormal If the solenoid is failed and stuck in its ON or OFF state (electrically or mechanically) the transmission is fixed in 4th speed to maintain mobility.
11. Front brake solenoid abnormal If the solenoid is failed and stuck in its ON state (electrically or mechanically) the transmission is fixed in 5th speed, and when the solenoid is failed and stuck in its OFF state (electrically or mechanically) the transmission is fixed in 4th speed to maintain mobility.
12. High and low reverse clutch solenoid abnormal If the solenoid is failed and stuck in its ON or OFF state (electrically or mechanically) the transmission is fixed in 4th speed to maintain mobility.

1. Transfer clutch solenoid abnormal If the solenoid is failed and stuck in its ON or OFF state, the transfer solenoid output is constantly turned OFF.
2. Turbine sensor 1, 2 abnormal Shifting control is performed without using turbine sensor values to maintain minimum mobility. 5th speed and manual mode are inhibited.
3. TCM data communication abnormal If communication with the memory box on the control valves fails, backup values stored in the TCM are used for controlling the solenoids.
4. CAN communication abnormal If an abnormality occurs in CAN communication, data received via CAN communication are fixed to preset values to perform shift control and maintain minimum mobility. Lockup and manual mode are inhibited.

Scheme 108

The transmission mounting consists of a pitching stopper, cushion rubber, and a cross member.

In addition to support the transmission, these components absorb noise and vibration caused by the transmission.

Scheme 109