Transmission - Design and Function: Other Volvo V40 I рестайлинг

General

OBD II is a diagnostics system designed to meet statutory requirements. Fault-tracing instruments can be plugged in to the OBD II socket in order to read diagnostic trouble codes (DTCs) and system parameters. OBD II contains only emission related diagnostic trouble codes (DTCs) and parameters and cannot provide the comprehensive range of information available from the Volvo On-board diagnostics system.

OBD II-codes

*) Activates malfunction indicator lamp (MIL).

Scheme 385

The gear selector is mechanically connected to the transmission by a cable, which operates the gear selector valve in the control system. There are two switches beside the gear selector for selecting the driving mode. One button (S) switches between the ECONOMY (E) and SPORT (S) modes. The other button makes it possible to engage the driving mode WINTER (W).

The gear selector has 6 positions, with the following functions

1. P Park position.
2. R Back-up (reverse) position.
3. N Neutral position.
4. D Automatic shifting between all gears. (Not applicable when mode selector is in the WINTER position.)
5. 3 In this position the 4th gear is blocked. The warning light on the instrument panel lights. Automatic shifting occurs between the other gears. (Not applicable when mode selector is in the WINTER position.)
6. L In this position only the 1st and 2nd gears operate. The warning light on the instrument panel lights. Automatic downshifting occurs, but upshifting is inhibited. If the gear selector is moved to position L at a road speed exceeding approximately 25-40 km/h (ECON) or 10-15 km/h (SPORT), 2nd gear will be engaged. If the speed is reduced to below approximately 25- 40 km/h (ECON) or 10-15 km/h (SPORT), the transmission will shift down to 1st gear. However, upshifting will not take place, regardless of vehicle speed. (The speed variations depend on which engine the transmission is used with and do not apply when the WINTER mode is selected.)

Scheme 386

Mode selector (S), ECONOMY and SPORT modes

The ECONOMY and SPORT mode selector is a rocker switch that remains in the selected position (E or S). ECONOMY and SPORT modes disengage each other.

The switch has one red and one green LED. The red LED lights in SPORT mode and the green LED illuminates the switch. When ECONOMY is engaged the red LED goes out.

ECONOMY or SPORT modes will be used when the ignition is switched on, depending on the position of the button. In SPORT mode the signal to the transmission control module (TCM) is grounded. In ECONOMY mode the signal is 0-2 V below battery voltage.

Mode selector WINTER program (W)

The WINTER mode selector is a spring loaded switch that engages and disengages WINTER mode.

The switch has a green LED that illuminates it.

When the ignition is switched on WINTER mode is always disengaged. WINTER mode is engaged by pressing the button (briefly). WINTER mode remains engaged until the button is pressed again, until ECONOMY or SPORT modes are engaged or until the ignition is switched off.

When the button is pressed the signal to the transmission control module (TCM) is grounded and when it is released the signal is 0-2 V below battery voltage.

Scheme 387

Driving modes

ECONOMY mode

This driving mode is intended for "normal" driving and provides early upshifting combined with lock-up. In addition, the transmission line pressure is modulated to provide smooth gear engagement. At wide open throttle (WOT), the kickdown function is engaged and shifting occurs at higher engine speeds. In this way extra performance is available when overtaking, for example.

SPORT mode

In SPORT mode gear-shift timing is designed to provide maximum performance. As long as acceleration is gently applied, shifts occur as for Economy mode. During increased acceleration, the control module selects the shift and lock-up points for the best possible performance. Kickdown can be activated if necessary.

WINTER mode

Winter mode makes it possible to start driving in high gear to avoid wheelspin on slippery roads. This mode can also be used in other problem situations in which the driver needs more direct control over gear selection. Lock-up is engaged in all gears except 1st. Depending on the gear position, the following combinations can be obtained

1. D The car starts in 3rd gear. Automatic shifting between 3rd and 4th gears occurs according to ECONOMY mode, D position.
2. 3 The car starts in 2nd gear. No up or downshifting.
3. L The car starts in 1st gear. No up or downshifting.

When WINTER mode is selected the warning lamp on the dashboard lights.

If kickdown is activated in Winter mode, the transmission uses all gears for maximum performance.

Scheme 388

The transverse automatic transmission contains three planetary trains with the accompanying brakes, clutches and freewheels. The twin shafts (a primary and secondary shaft), are located side by side. The rear (P1) and front planetary trains (P2) form the primary shaft of the transmission. P1 is a single planetary train. P2 has double planetary gear sets, an inner set consisting of the long planetary gears and an outer set consisting of the short planetary gears. The inner planetary gear, like the sun gear shaft, is common to both P1 and P2. The single planetary train P3 comprises the secondary shaft of the transmission.

The power flow from the primary to the secondary shaft passes through two intermediate gears (12, 13), and from the secondary shaft to the final drive via a driving (14) and a driven (15) final drive gear. There are a total of four brakes (B1- B4); B4 is a band brake, three clutches (C1- C3) and three freewheels (F1-F3).

A built-in oil pump (16) lubricates the moving parts of the transmission and provides the required oil pressure for the hydraulics.

Brakes and clutches are activated by shift valves in the hydraulic control system. By applying them in various combinations, four forward gears and one reverse gear can be obtained.

The torque converter has a lockup clutch. When this clutch is not engaged, some slippage occurs in the torque converter, resulting in torque ratios proportional to the slippage. When lockup is engaged, a mechanical coupling is achieved between the engine and the transmission. This eliminates slippage and results in good fuel economy. The AW 50-42 is electronically controlled, allowing lockup to be engaged in the three highest gears.

Scheme 389

The gear-shift position sensor has a park / neutral position (PNP) function to prevent the engine being started with a gear selected.

This function prevents the engine being started unless the P or N positions are selected. This prevents the car from lurching forwards when started.

Shift lock and ignition switch interlock

(Certain markets only)

Scheme 390

Shift lock

Cars in certain markets are equipped with an electrically operated shift lock function. This is to prevent the gear selector from being inadvertently moved from the P position. This locks the gear selector interlock pin (1) in the interlock section, locking the selector lever in the P position. Figure A.

The ignition must be switched on and the brake pedal depressed before the gear selector can be moved from the P position. (The stop (brake) light is actuated.)

Scheme 391

When the ignition is switched on and the brake pedal is depressed, a solenoid (2) is activated in the gear selector assembly. The solenoid armature (3) is pushed in and the gear selector lock button can be pressed down as usual to select another gear.

Shift lock is supplemented with another safety function, the ignition switch interlock. This is connected to the ignition switch by a cable. The ignition switch interlock is controlled by the gear selector position and the position of the lock cylinder (4) in the ignition switch. This means that the gear selector has to be in the P position before the ignition key can be removed from the ignition. The ignition switch interlock function is only available in combination with the shift lock.

Scheme 392

Shift lock override

To permit the gear selector to be moved from the P-position when there is no battery voltage, or if there is a fault in the shift lock mechanism, the interlock mechanism can be disconnected mechanically. The mechanical release consists of a button (5) on the gear selector assembly marked SHIFT-LOCK OVERRIDE. The ignition key must be in position I or II. When the button (5) is pressed, the solenoid lock pin (3) is released. The gear selector can now be moved from the P position if the gear selector lock button is pressed.

While the fault remains, the mechanical release must be used together with the ignition key every time the gear selector is moved from the P position.

There is a microswitch (6) in the electrical circuit between the stop (brake) light switch and the solenoid. The microswitch only closes the circuit in the P position. This is so that the solenoid is not activated every time the driver presses the brake pedal when driving.

Activating components / functions

Use this function to activate the system components / functions individually at a frequency of 0.5 Hz. To activate

1. Vehicle speed must be 0 km/h
2. The gear selector must be in position P or N

The following components can be activated

1. Shift solenoid S1
2. Shift solenoid S2
3. Lock-up solenoid SL
4. Line pressure solenoid STH
5. The warning lamp in the combined instrument panel
6. Constant idle speed compensation, P/N position and torque limiting

The control module has an integrated diagnostics system (the Volvo On-board Diagnostics (OBD). The control module continuously monitors itself and the input and output signals in the system. If the control module detects a fault it stores a diagnostic trouble code (DTC) and the check and warning lamps begin to flash. When a diagnostic trouble code (DTC) is stored, the system registers and freezes the value of 3 different parameters. These are stored together with the diagnostic trouble code (DTC). The control module can store up to 7 diagnostic trouble codes (DTCs). If the total number of diagnostic trouble codes (DTCs) exceeds 7, the four first diagnostic trouble codes (DTCs) will always be saved, while the last three will be the latest diagnostic trouble codes (DTCs) to be stored.

When a transmission fault is registered by the control module (permanent fault), an emergency program is activated to deal with the fault. The transmission control module (TCM) takes corrective action to protect the transmission and maintain as much driveability as possible. There are different emergency programs depending on the type of fault and how serious it is

1. Emergency mode I
2. Emergency mode II
3. Emergency mode III
4. Limp home mode

Emergency mode I is activated for minor faults. Limp-home mode is activated for the most serious faults. For a more detailed description of the emergency programs, see Emergency programs .

If the fault disappears (is intermittent), the transmission control module (TCM) returns to normal operation the next time the ignition is switched on. The indicator and warning lamps will stop flashing after the ignition is switched on and off a certain number of times. The ignition may have to be switched on up to five times, depending on the diagnostic trouble code (DTC) that has been stored.

If a fault disappears after a diagnostic trouble code (DTC) has been permanently stored in the control module, information about the fault remains stored in the control module.

For each diagnostic trouble code (DTC) stored, a counter records the total number "fault-free" operating cycles since the diagnostic trouble code (DTC) was stored. When the counter is at 0, the control module treats the malfunction as a permanent fault. If the counter value is greater than 0, the transmission control module (TCM) interprets it as an intermittent fault. If the fault recurs, the counter is reset to 0.

Reading off input and output signals

The values and status of the control module input and output signals can be continuously monitored using this function.

The following parameters can be read off

1. Shifting program, gear-shift position sensor, status
2. Gear-shift position sensor, position
3. Gear-shift position sensor, signal A
4. Gear-shift position sensor, signal B
5. Gear-shift position sensor, signal C
6. Gear-shift position sensor, signal PA
7. Mode selector, ECONOMY / SPORT (E/S), position
8. Mode selector, WINTER (W), position
9. Shifting program, mode selector, position
10. Stop (brake) light switch, position
11. Kickdown switch, position
12. Kickdown position, shifting, status
13. Throttle position (TP) sensor, signal
14. Throttle position (TP) sensor, position
15. Oil temperature sensor, signal
16. Oil temperature, value
17. Battery voltage, value
18. Vehicle speed, value
19. Transmission input speed, value
20. Engine speed (RPM), value
21. Load signal from the engine control module (ECM), value
22. Gear in relation to solenoids S1, S2 and SL, status
23. Gear in relation to gear ratio, status
24. Activation of shift solenoid S1, status
25. Shift solenoid S1, position
26. Activation of shift solenoid S2, status
27. Shift solenoid S2, position
28. Activation of lock-up solenoid SL, status
29. Lock-up solenoid SL, position
30. Line pressure solenoid STH, %, control
31. Line pressure solenoid STH, amperage
32. Constant idle speed compensation P/N position and torque limiting when shifting, status
33. Warning lamp in the combined instrument panel, status
34. Emergency programs in the event of a fault, status.

Information about faults and other data can be read off using the VIDA PC connected to the data link connector (DLC).

With the VIDA PC it is possible to

1. Read and erase diagnostic trouble codes (DTCs), counters and frozen values.
2. Activate components / functions according to certain predetermined patterns.
3. Continuously monitor the value and status of the input and output signals for the system.
4. Read off the control module identification.

To activate the Volvo on-board diagnostic (OBD) system

1. The ignition on must be on.
2. Battery voltage must be above 11 V.

To activate components / functions

1. Vehicle speed must be 0 km/h.
2. The gear selector must be in position P or N.

Scheme 393

The control module has a built-in diagnostic system, the Volvo on-board diagnostic (OBD) system. This system continuously monitors its own system and the input and output signals.

Using this function, the status of the control module input and output signals can be continuously read off.

For further information about parameters, see Description of parameters .

Activating components

This function allows components to be activated so that their functions can be checked.

For further information about activations, see Description of activations .

This function allows a number of components to be activated so that their functions can be checked. The following components can be activated

Shift solenoids S1, S2, S3, S4, S5

Activating shift solenoids S1, S2, S3, S4, S5

"Clicking sound" in the transmission (use a stethoscope) and the status should change between OFF/ON.

Linear pressure solenoid SLU, SLS, SLT

Activating the linear pressure solenoids SLU, SLS and SLT.

"Clicking sound" in the transmission (use a stethoscope) and the current must vary.

Emergency programs

An emergency program is activated to deal with the fault when the transmission control module (TCM) detects a transmission fault (permanent fault). The control system takes corrective action to protect the transmission and maintain as much driveability as possible. Minor malfunctions do not activate an emergency program. There are different programs depending on the type of malfunction detected.

Emergency mode I

Emergency mode II

Emergency mode III

Limp-home mode

Emergency mode I is activated in the event of minor faults and the Limp-home mode is activated for the most serious faults. If the malfunction is intermittent, the transmission control module (TCM) returns to normal operation the next time the ignition is switched on.

Emergency mode I

1. The combined instrument panel warning lamp flashes for certain diagnostic trouble codes (DTCs).
2. The transmission shifts in all gears but transmits no signal to the lock-up solenoid. This means that lock-up is not available.
3. There is no adaptation of the gear slippage times at high altitude (High Altitude Compensation) which can result in poor gear shifting quality.

Emergency mode II

1. As for Emergency mode I
2. No reduction of line pressure when moving the gear selector between positions P-R, N-R and N-D. This results in harsh shifting.
3. No torque limiting request to engine control module (ECM) when shifting.
4. The warning lamp in the combined instrument panel flashes.

Emergency mode III

1. Remedy as for Emergency modes I and II.
2. No control of line pressure solenoid STH. Constant maximum system pressure. This results in harsh shifting and harsher gear engagement in positions P-R, N-R and N-D.

Limp-home mode

1. The transmission control module (TCM) stops activating solenoids, which results in the transmission not shifting at all. The transmission operates only in 3rd gear in positions 3 and L, 4th gear in position D and reverse in position R. Shifting can only be carried out manually between 3rd and 4th gear (D position) and reverse gear.
2. No control of line pressure solenoid STH. Constant maximum system pressure. This results in harsh shifting and harsher gear engagement in positions P-R, N-R and N-D.
3. The warning lamp in the combined instrument panel flashes.

Note. When starting and driving, the gear selector should first be moved to position L to minimize stress on the transmission.

Scheme 394

Clutches

1. C1- Engages the input shaft with the rear planetary train (P1) ring gear.
2. C2 - Engages the input shaft with the sun gear shaft for the primary shaft planetary trains (P1, P2).
3. C3 - Engages the planetary gear carrier with the sun gear for the secondary shaft planetary gear (P3).

Brakes

1. B1 - Locks the sun gear shaft for the primary shaft planetary trains (P1, P2) so that it cannot rotate in any direction.
2. B2 - Locks, using F1, the sun gear shaft for the primary shaft planetary trains (P1, P2) so that it cannot rotate counter-clockwise.
3. B3- Locks the front planetary train (P2) ring gear so that it cannot rotate in any direction.
4. B4 - Locks the sun gear for the secondary shaft planetary train (P3) so that it cannot rotate in any direction.

Freewheel

1. F1 - Prevents the sun gear shaft for the primary shaft planetary trains (P1, P2) from rotating counter-clockwise when B2 is engaged.
2. F2 - Prevents the front planetary train (P2) ring gear from rotating counter-clockwise.
3. F3 - Prevents the sun gear for the secondary shaft planetary train (P3) from rotating clockwise.

Gear shift solenoids

1. S1 - Controls shifting in the transmission. Activated in 2nd and 3rd gears.
2. S2 - Controls shifting in the transmission. Activated in back-up (reverse) gear, 1st and 2nd gears.

Scheme 395

The transmission control module (TCM) is located by the engine control module (ECM) inside the center console under the dashboard.

Scheme 396

The transmission control module (TCM) P/N and serial numbers are stamped on a plate on the unit.

1. Volvo P/N
2. Identification code
3. Version
4. Serial number
5. Number according to car specification, type code

Scheme 397

The transmission control module (TCM) exactly determines gear shift and lock-up engagement points based on the driving mode selected. To do this it receives information about the following

1. Selected gear - from the gear-shift position sensor (8).
2. Selected driving mode - from the mode selector (11).
3. Vehicle speed - from the ABS system (17).
4. Transmission input shaft RPM - from transmission speed sensor (5).
5. Engine speed and load - from the engine control module (ECM) (18).
6. Throttle opening - from the engine control module (ECM) (18).
7. Brake pedal position - from the stop (brake) light switch (19).
8. Whether the accelerator pedal (AP) is fully depressed - from the kickdown switch (20) on the floor under the accelerator pedal (AP).
9. Transmission fluid temperature - from a temperature sensor (6) in the transmission.

All of this information is processed by the transmission control module (TCM) (21). The control module calculates which gear will provide the best driving performance for the driving mode selected. The transmission control module (TCM) orders gear shifting by transmitting gear shifting signals to two shift solenoids (S1, S2) in the transmission. Depending on the input signals, the control module determines if and when torque converter lock- up should be activated. Lock- up is engaged with the help of a special solenoid (SL).

During gear shifting the transmission control module (TCM) modulates the transmission oil pressure via a line pressure solenoid (STH), while simultaneously sending a torque limiting signal to the engine control module (ECM) (18).

The transmission control module (TCM) is also connected to the data link connector (DLC) (22). Faults occurring in the electronic system are recorded in the control module memory for subsequent display as diagnostic trouble codes (DTCs). If a fault is serious enough to require immediate attention, the warning lamp (23) in the combined instrument panel flashes.

The gear-shift position sensor (8) provides the transmission control module (TCM) with information about the selected gear.

Engine torque is reduced during some gear shifts to provide smoother gear shifting and to minimize transmission wear. To control these functions a torque limiting request is transmitted to the engine control module (ECM) via a cable. This cable is also used to inform the engine control module (ECM) which position the gear selector is in. This is so the engine control module (ECM) can adjust the engine speed (RPM) when a gear is engaged.

The speed signal comes from the vehicle speed sensor (VSS) (17) which receives pulses from a pulse wheel, the locking wheel for the shift-lock on the output shaft. Transmission speed information is transmitted by the transmission speed sensor (5).

Information about engine speed and load comes from the engine control module (ECM). The engine control module (ECM) also provides information about the throttle opening.

If the brake pedal is depressed, the brake light switch closes and transmits a signal to the control module.

When the accelerator pedal (AP) is fully depressed, the kickdown switch (20) closes.

The transmission control module (TCM) uses the above signals to calculate the following

1. The control module determines the engine power output by comparing information about the throttle opening with the values for engine load and speed. This forms the basis for calculating gear shift engagement pressure.
2. Signals from the stop (brake) light switch are used to disengage lock- up during braking in order to avoid slap in the transmission.

Scheme 398

The transmission control module (TCM) activates the indicator and warning lamp in the combined instrument panel. The lamp lights continuously when the ignition is switched on and when driving if

1. The gear selector is in positions 3 or L
2. Driving mode W (winter) has been selected.

The lamp flashes when the engine has been started if

1. The transmission control module (TCM) has detected a fault in the transmission.

If the fault becomes intermittent, the indicator and warning lamp will go out after the ignition has been switched on and off a certain number of times. The ignition may have to be switched on up to five times, depending on the diagnostic trouble code (DTC) that has been stored. For diagnostic trouble code (DTC) AT-235, High Oil temperature, the lamp flashes only as long as the temperature of the oil exceeds +140°C.

Scheme 399

In addition to the manually-selectable gear-change programs (ECON, SPORT, WINTER), the control module incorporates a number of pre-programmed functions which ensure that the correct gear is selected at all times based on the prevailing driving conditions. These functions vary by market and engine variant.

1. A When driving at high altitude, engine power is reduced because there is less oxygen in the air. The control module provides High Altitude Compensation by adjusting gear engagement times to suit the prevailing conditions, thereby maintaining high shifting quality.
2. B When the gear shift selector is in position D and the mode selector is set to ECON/SPORT, and the control module simultaneously senses the throttle position and any increase or decrease in the road speed. The relationship between the throttle opening and speed change is a measure of road gradient. The control module uses this information to select a gear. This function is known as "Up Slope Mode".
3. C If the transmission temperature increases abnormally as a result of heavy load under high ambient temperature conditions, the torque converter lock- up function is activated as often as possible (temperature controlled lock-up). This reduces slippage and the generation of heat in the transmission. If the temperature drops below +20°C the lock-up function will not be engaged. (This temperature can vary slightly depending on transmission type.) At low temperatures the transmission control module (TCM) increases the transmission line pressure, shortening gear engagement times.
4. D/E The transmission control module (TCM) is also programmed with safety functions preventing the manual engagement of low gears if the speed is too high. Nor can reverse gear be engaged if the speed exceeds approximately 5 km/h, even if the gear selector is moved to position R.
5. F In the event of a malfunction in the electronic system the warning light in the combined instrument flashes (does not apply to all faults), and the control module switches to a special emergency program. The control system implements corrective action to protect the transmission, while leaving the car in a driveable condition. This makes it possible to drive the car to a workshop for repairs.

Scheme 400

Primary shaft (P1, P2)

The input shaft rotates clockwise. All clutches and brakes are disengaged, and no power is transferred to the planetary trains.

Secondary shaft (P3)

No power is transmitted to the secondary shaft. B4 locks the sun gear so that it cannot rotate in any direction. Shift-lock (P), which is actuated by the mechanical linkage, is engaged by means of the locking wheel on the output shaft and prevents the car from rolling.

Position N (Neutral)

Primary shaft (P1, P2)

The input shaft rotates clockwise. All clutches and brakes are disengaged, and no power is transferred to the planetary trains.

Secondary shaft (P3)

No power is transmitted to the secondary shaft. B4 locks the sun gear so that it cannot rotate in any direction. Shift-lock (P) is disengaged. The planetary gears can rotate freely around the sun gear, and the car can start to roll if parked on an incline.

Brake B4 is activated in both P and N in order to minimize engagement impact. Otherwise this occurs when several brakes and clutches are activated simultaneously, when the gear selector is moved to position D or R. Because B4 is also applied in both 1st gear and reverse, the number of simultaneous engagements is reduced.

Scheme 401

Primary shaft (P1, P2)

The input shaft rotates clockwise and C1 connects the input shaft with the rear planetary train (P1) ring gear so that it rotates clockwise at the input shaft RPM. The inner planetary gears in P1 rotate clockwise. (The sun gear shaft rotates counter-clockwise.)

F2 prevents the front planetary train ring gear from rotating counter-clockwise. The outer planetary gears in P2 rotate counter-clockwise and at the same time move clockwise around the inner planetary gears. The planetary gear carrier and the driving intermediate gear rotate clockwise as a unit at lower speed than the input shaft.

Secondary shaft (P3)

Because the driving intermediate gear rotates clockwise, the driven intermediate gear and P3 ring gear are driven counter-clockwise. The planetary gears rotate counterclockwise. B4 and F3 lock the sun gear so that it cannot rotate in any direction.

The planetary gears rotate counter-clockwise and at the same time move counter-clockwise around the sun gear. The planetary gear carrier and the driving final drive gear rotate counter-clockwise as a unit. The driven final drive gear rotates clockwise at lower speed than the driven intermediate gear.

Scheme 402

Secondary shaft (P3)

The driven final drive gear rotates clockwise. The driving final drive gear and the planetary gear carrier rotate counter-clockwise as a unit.

B4 and F3 lock the sun gear so that it cannot rotate in any direction. The planetary gears rotate counter-clockwise and at the same time move counter-clockwise around the sun gear. The ring gear and the driven intermediate gear rotate counter-clockwise.

Primary shaft (P1, P2)

The driving intermediate gear and the planetary gear carrier rotate clockwise as a unit. B3 locks the front planetary train (P2) ring gear so that it cannot rotate in any direction, providing an engine brake. (In D and 3, B3 is not applied, so that no engine braking can be obtained, because of F2.)

The outer planetary gears in P2 rotate counter-clockwise and at the same time move clockwise around the inner planetary gears, which rotate clockwise.

The sun gear shaft rotates counter-clockwise, as B2 and B1 are not applied.

The rear planetary train (P1) ring gear rotates clockwise. C1 connects the rear planetary train ring gear together with the input shaft so that they rotate clockwise as a unit.

Scheme 403

Primary shaft (P1, P2)

The input shaft rotates clockwise and C1 connects the input shaft together with the rear planetary train ring gear so that it also rotates clockwise at the input shaft speed.

B2, F1 and B1 prevent the sun gear shaft from rotating in any direction. F2 is in freewheel mode. The inner planetary gears rotate clockwise and at the same time move clockwise around the sun gear shaft. The planetary gear carrier and the driving intermediate gear rotate clockwise as a unit.

Secondary shaft (P3)

The power flow here is the same as in position D for 1st gear. As the driving intermediate gear rotates clockwise, the driven intermediate gear and P3 ring gear will be driven counter-clockwise. The planetary gears rotate counterclockwise.

B4 and F3 lock the sun gear so that it cannot rotate in any direction. The planetary gears rotate counter-clockwise and at the same time move counter-clockwise around the sun gear. The planetary gear carrier and the driving final drive gear rotate counter-clockwise as a unit.

The driven final drive gear rotates clockwise at lower speed than the driven intermediate gear.

Scheme 404

Primary shaft (P1, P2)

The power flow here is the same as in position D for 2nd gear. The input shaft rotates clockwise and C1 connects the input shaft together with the rear planetary train ring gear, so that it also rotates clockwise at the input shaft speed.

B2, F1 and B1 prevent the sun gear shaft from rotating in any direction. (F2 is in freewheel mode.) The inner planetary gears rotate clockwise and at the same time move clockwise around the sun gear shaft. The planetary gear carrier and the driving intermediate gear rotate clockwise as a unit.

Secondary shaft (P3)

Because the driving intermediate gear rotates clockwise, the driven intermediate gear and the ring gear is driven counter-clockwise. C3 connects the sun gear and the planetary gear carrier together.

The planetary train ring gear, the planetary gear carrier, the sun gear and the driving final drive gear rotate counter-clockwise as a unit.

The driven final drive gear rotates clockwise at higher speed than in 2nd gear.

Scheme 405

Primary shaft (P1, P2)

The input shaft rotates clockwise and C1 connects the input shaft together with the rear planetary train ring gear so that it also rotates clockwise at the input shaft speed.

C2 couples the sun gear shaft together with the input shaft so that the sun gear shaft rotates clockwise. The inner planetary gears do not rotate.

B2 and F1 prevent the sun gear shaft from rotating counterclockwise. The entire primary shaft (planetary trains P1 and P2) rotates clockwise as a unit.

The driving intermediate gear rotates clockwise at the input shaft speed.

Secondary shaft (P3)

The power flow is the same as in position D for 3rd gear. The driving intermediate gear rotates clockwise and the driven intermediate gear and the ring gear are driven counter-clockwise.

C3 connects the sun gear and the planetary gear carrier together. (F3 permits freewheel mode.) The planetary train ring gear, the planetary gear carrier, the sun gear and the driving final drive gear rotate counter-clockwise as a unit.

The driven final drive gear rotates clockwise at higher speed than in 2nd gear.

Scheme 406

Primary shaft (P1, P2)

The input shaft rotates clockwise and C2 connects the input shaft with the sun gear shaft so that it also rotates clockwise at the input shaft speed. The inner planetary gears rotate counter-clockwise. The outer planetary gears rotate clockwise and at the same time move around the inner planetary gear.

B3 locks the front planetary train ring gear so that it cannot rotate in any direction. The ring gear and the driven intermediate gear rotate counter-clockwise.

Secondary shaft (P3)

Because the driving intermediate gear rotates counter-clockwise, the driven intermediate gear and the ring gear are driven clockwise as a unit. B4 locks the sun gear so that it cannot rotate in any direction.

The planetary gears rotate clockwise and at the same time move clockwise around the sun gear. The planetary gear carrier and the driving final drive gear rotate clockwise. The driven final drive gear rotates counter-clockwise.

Scheme 407

The AW 50-42 is an electronically-controlled four speed automatic transmission with torque converter lock-up of the three highest gears. Because the transmission is controlled by an electronic control module, gear-shifting can be controlled to allow the correct gear to be selected for driving conditions, engine load, driver's wishes, speed, etc. This gives good fuel economy combined with top-class performance and increased comfort by ensuring smoother gearshifting and lower noise levels.

A control module receives information about the selected gear and driving mode setting. This, together with signals from a number of sensors providing information about the running conditions of the car, is processed by the control module. The control module calculates the optimum gear shifting and lock-up engagement points, depending on the driving mode selected. The control module then controls gearshifting and lock-up engagement by acting on the transmission hydraulic system. The control module also affects the quality of gearshifting by adjusting hydraulic line pressure at the instant of gear shifting.

The transmission's electronic control system receives continuous information from a number of sensors, as well as from the engine management system. Unlike transmissions with exclusively hydraulic control systems, the control system can adapt to extremely small changes in operating conditions. It can control the different transmission functions so that the correct gear for the driving mode selected by the driver, is always selected.

To facilitate fault-tracing, the control module has a built-in on-board diagnostic system (OBD II system) which records any faults in the control system and transmission. These faults can be read off via the data link connector (DLC).

Scheme 408

The transmission's mechanical components are enclosed in the torque converter housing (1), the transmission housing (2), with integrated final drive housing (3) and in the valve housing cover (4).

The transmission speed sensor (5) in the transmission housing, the temperature sensor (6), the vehicle speed sensor (VSS) (7) and the gear-shift position sensor (8), which is acted on by the gear shift linkage rod are, like other electric components, connected to a connector (9).

The gear-shift position sensor, which informs the control module the gear that has been selected, also contains a back-up (reversing) light and a park / neutral position (PNP) switch.

The solenoid valves (SL, S1, S2, STH) are located in the hydraulic system valve housing (control system), which is located beneath the valve housing cover on the transmission. Lock-up solenoid SL regulates the torque converter lock-up function. Both the gear shift solenoids S1 and S2 control shifting. These valves are activated by the transmission control module (TCM), as is the line pressure solenoid valve STH, that controls the transmission line pressure.

The transmission speed sensor (5) is activated by a toothed impulse wheel. By comparing the engine and transmission speeds, the control module can determine the amount of slippage in the torque converter.

The electromagnetic vehicle speed sensor (VSS) (7) is activated by a toothed impulse wheel. The sensor sends vehicle speed status signals to the transmission control module (TCM).

An NTC type temperature sensor (6) measures the oil temperature. The control module receives this information and uses it to calculate gear shifting and lock-up engagement points (temperature controlled lock-up). The lower limit for temperature activated lock- up is at an oil temperature of 20- 30° C. Below this limit there is no lock- up function engagement so the transmission reaches its normal operating temperature faster. An upper limit with enhanced engagement also occurs at approximately 115° C. This reduces slippage and therefore heat generation in the transmission.

The gear-shift position sensor has three separate functions

1. Transmitting an electronic signal to inform the control module which gear has been selected.
2. Operating the back-up (reversing) lamp when the gear selector is in position R.
3. Preventing the engine from being started unless the gear selector is in the P or N positions.

The transmission and final drive share a common oil pan. A dipstick in the engine compartment is used to check the transmission oil.