The automatic transmission is an electronically controlled 4-speed transmission designed for front wheel drive vehicles.
The individual ratios are achieved through two planetary gear sets connected one behind the other.
The individual components of the planetary gear sets are driven or held by means of three multiplate clutches, a multiplate brake, a brake band and a roller one-way clutch.
The torque is transmitted to the final drive assembly through an intermediate gear stage.
The automatic transmission fluid is changed as directed by the Scheduled Maintenance Guide that is supplied with the vehicle.
The manual selector lever gives the driver a choice of "P" (PARK), "R" (REVERSE), "N" (NEUTRAL), "D" (DRIVE), "M" (MANUAL MODE), "+" (TIP UP) and "-" (TIP DOWN).
The transmission has electronic synchronous shift control (ESSC) which guarantees extremely smooth gear shifting over the entire life of the transmission.
The transmission can be diagnosed and tested using Worldwide Diagnostic System (WDS) through the data link connector (DLC), in the passenger compartment.
Transmission ratios in the individual gears:
Torque Converter Housing with Torque Converter Assembly and Transmission Fluid Pump Assembly
1
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Torque converter housing and impeller
4
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Torque converter lock-up clutch
5
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Transmission input shaft
The torque converter transmits the engine torque hydraulically to the transmission input shaft.
The stator boosts the torque to the input shaft (approximately 85% difference in speed between the impeller and the turbine).
The stator is made of synthetic resin to reduce weight.
To increase the efficiency of the automatic transmission, the torque converter has a lock-up clutch. When the torque converter lock-up clutch is closed, the torque is transmitted directly from the crankshaft through the torque converter housing to the transmission input shaft.
Transmission Fluid Pump and Stator Support
2
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Transmission fluid pump
3
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Torque converter impeller hub
The transmission fluid pump is a crescent gear pump and is driven directly from the crankshaft by means of drivers on the torque converter impeller hub. The transmission fluid pump is bolted to the transmission case.
The stator support is part of the transmission fluid pump. Splines on the stator support locate and hold the torque converter stator.
Planetary Gear Sets
The individual gears are shifted by means of two planetary gear sets connected one behind the other.
Clutches and Bands
The individual gear ratios are selected by means of four multiplate clutches, a brake band and a roller one-way clutch.
The components are controlled by the transmission control module (TCM) through pulse width modulation (PWM) solenoid valves.
Valve Body
1
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Solenoid shift control valve assembly
2
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Solenoid shift control (ON and OFF) valves
3
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Solenoid electrical pressure control valve
The solenoid shift control valves and the solenoid shift control ON and OFF valves supply pressure to the individual clutches and bands to shift the gears.
The solenoid shift control valves allow direct actuation of the clutches and bands to make sure extremely smooth gear shifting through precise pressure regulation.
The solenoid electrical pressure control valve (variable force solenoid) make sure that sufficient hydraulic pressure is available in all operating conditions.
Solenoid Shift Control Valves
The solenoid shift control valves control the pressure to the bands and clutches.
Solenoid Shift Control (ON and OFF) Valves
The solenoid shift control (ON and OFF) valves switch the different oil passages in the valve body to direct the pressure to the individual clutches and bands.
Solenoid Electrical Pressure Control Valve (variable force solenoid)
The solenoid electrical pressure control valve (variable force solenoid) controls the required main line pressure for the individual transmission ranges.
The main line pressure is dependent on engine load.
Internal Shift Mechanism
3
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Parking pawl engaging lever
4
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Lever and bracket assembly
The manual shaft lever is secured on a square on the manual shaft. Axial movement of the selector lever cable is changed into rotational movement of the manual shaft.
The manual shaft operates the manual shaft parking pawl engaging lever and the actuating lever of the manual valve.
The manual valve, a valve operated entirely manually, is moved by means of the manual valve actuating lever in the valve body.
The manual valve guarantees the functions during hydraulic emergency operation.
Intermediate Gear Stage and Final Drive Assembly
2
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Transfer shaft input gear
3
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Transfer shaft output gear
The final drive input gear is splined to the planet carrier of the front planetary gear set and drives the transfer shaft input gear of the intermediate gear stage.
The transfer shaft output gear of the intermediate gear stage drives the final drive assembly.
The torque is transmitted to the halfshafts through the final drive assembly.
The differential offsets the differences in the speed of rotation of the halfshafts.
The intermediate gear stage is designed so that the final drive ratio can be adapted to requirements when the transmission is used in conjunction with different engines.
Transmission Control System
The transmission control module (TCM) is separate from the powertrain control module (PCM) and is mounted on the firewall on the left-hand side of the vehicle.
During routine servicing, the TCM must be calibrated using the WDS.
The new TCM changes the following modes of the transmission control system.
• Select shift mode
• Fast-off mode
• Kickdown mode
In select shift mode, the gears can be selected manually using the gear selector lever.
The fast-off mode prevents the transmission from shifting to a higher gear when the driver suddenly removes foot pressure from the accelerator pedal. The advantage of the engine braking effect is more effective by remaining in the lower gear.
The kickdown mode allows the transmission control system to differentiate between kickdown and wide open throttle (WOT).
Electronic Synchronous Shift Control (ESSC)
Control of Shift Operations
During a shift operation certain elements are released while others are actuated. Ideally this process takes place simultaneously (synchronously) to avoid jerky gear shifting.
When the shift operation is controlled conventionally, the pressure build up and reduction at the shift elements are set and defined for ideal conditions (synchronous shifting).
Control of Shift Operations with ESSC
The ESSC monitors the shift operations and is able to adapt to the wear in the shift elements over the life of the transmission.
The system monitors the shift time whether the shift operation is synchronous.
If the TCM detects a deviation from the stored values for the shift time and synchronization of the shift operation, the pressure build up or reduction is adapted accordingly.
Turbine Shaft Speed (TSS) Sensor
The TSS sensor is located on the transmission case over the transmission input shaft.
The TSS sensor is an inductive sensor, which senses the speed of rotation of the transmission input shaft.
If the TSS sensor fails, the signal of the output shaft speed (OSS) sensor is used as a substitute signal.
Output Shaft Speed (OSS) Sensor
The OSS sensor is located on the transmission case above the rotor in the differential.
The OSS sensor is an inductive sensor, which detects the vehicle speed by means of a rotor on the differential.
If the OSS sensor fails, the signal of the TSS sensor is used as a substitute signal.
Transmission Range (TR) Sensor
1
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Manual release mechanism cover
If the brake signal should fail, due to a malfunction, manual unlocking is possible.
NOTE:If position "P" is selected again the manual selector lever is locked again.
Remove the manual release mechanism cover and using a suitable object (ignition key), press into the opening until the manual selector lever can be moved out of position "P".
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