SOLENOID OPERATION CHART - CONVERTER ENGAGED
| Base Gearshift Selector Position | PCM Commanded Gear | Solenoid States - Converter Engaged | |||||
|---|---|---|---|---|---|---|---|
| SSA | SSB | SSC | SSD | SSE | PCA | ||
| D | 2 | Off | On | On | Off | On | |
| 3 | Off | On | On | Off | Off | ||
| 4 | On | On | On | Off | Off | ||
SOLENOID OPERATION CHART - CONVERTER ENGAGED
SOLENOID OPERATION CHART - CONVERTER DISENGAGED
| Base Gearshift Selector Position | PCM Commanded Gear | Solenoid States - Converter Disengaged | |||||
|---|---|---|---|---|---|---|---|
| SSA | SSB | SSC | SSD | SSE | PCA | ||
| P/N | P/N | On | Off | Not fed | Not fed | Not fed | |
| R | R | Off | Off | Not fed | Off | Not fed | |
| D | 1 | Off | Off | Off | On | On | |
| 1 (M) | On | On | Off | Off | On | ||
| 2 | Off | Off | Off | Off | On | ||
| 3 | Off | Off | Off | Off | Off | ||
| 4 | On | Off | On | Off | Off | ||
SOLENOID OPERATION CHART - CONVERTER DISENGAGED
Transaxle Description
The automatic transmission used in the vehicle is a new development.
It is a fully automatic, electronically controlled 4-speed transmission designed for front-wheel drive vehicles.
Its abbreviated designation 4F27E means
- 4 - 4-speed transmission
- F - front-wheel drive
- 27 - originally designed for maximum input torque after torque converter: 365 N.m (270 lb-ft)
- E - fully electronically controlled
Scheme 8
The individual ratios are achieved through 2 planetary gear sets, connected one behind the other.
The individual components of the planetary gear sets are driven or held by means of 3 multi-plate clutches, a multi-plate 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 manual selector lever gives the driver a choice of P, R, N, 1, 2 and D.
In drive range D it is also possible to operate an overdrive (O/D) switch on the manual selector lever to prevent the transmission from shifting into 4th gear. The default gear for this transmission is 3rd gear.
To minimize fuel consumption, the torque converter lock-up clutch is closed by the powertrain control module (PCM) in 3rd and 4th gears depending on the throttle position and vehicle speed.
The transmission has electronic synchronous shift control (ESSC), which guarantees extremely smooth gear shifting over the entire life of the transmission.
A hydraulic emergency operating program maintains limited operation in the event of failure of important electrical components.
The transmission can be tested using a scan tool through the data link connector (DLC) in the passenger compartment.
| Gear Ratio (Typical shown, ratios are model dependent) | |
|---|---|
| 1st | 2.816:1 |
| 2nd | 1.498:1 |
| 3rd | 1.000:1 |
| 4th | 0.726:1 |
| Reverse | 2.649:1 |
Scheme 9
| Item | Part Number | Description |
|---|---|---|
| 1 | 7G484 | Pulse width modulation (PWM) solenoid valves |
| 2 | 7H148 | Shift solenoid (on/off) valves |
| 3 | 7G353 | Main regulating valve variable force solenoid (VFS) |
The valve body contains 6 solenoid valves
- three pulse width modulation (PWM) solenoid valves
- two shift solenoid (on/off) valves
- one main regulating valve (variable force solenoid).
The individual clutches and bands are supplied pressure from the PWM solenoid valves and the shift solenoid (on/off) valves and thus the gears are shifted.
The PWM solenoid valves allow direct actuation of the clutches and bands to make sure extremely smooth gear shifting through precise pressure regulation.
The shift solenoid (on/off) valves switch the hydraulic path to the clutches and bands, reducing the number of required modulating valves.
The main regulating valve (variable force solenoid) makes sure that sufficient hydraulic pressure is available in all operating conditions.
When servicing the automatic transaxle, refer to the identification tag located on the case.
Scheme 10
| Item | Part Number | Description |
|---|---|---|
| 1 | Transmission assembly part number | |
| 2 | Sample build date code (DDMMYY) | |
| 3 | Sample Julian build date and build number (YDDDXXX) | |
| 4 | Service model code |
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.
The time for the shift operation should remain within the time limits provided.
When the shift operation is controlled conventionally, the pressure buildup and reduction at the shift elements are set and defined for ideal conditions (synchronous shifting).
As there is no way of influencing the control in the event of different levels of wear in the shift elements, when the transmission has been used for a fairly high mileage it is possible that the pressure buildup and reduction may no longer be synchronous.
The result or premature pressure reduction at the element to be switched off is an unwanted rise in the turbine shaft speed as the element to be switched on cannot transmit the input torque.
The result of delayed pressure reduction at the element to be switched off is an unwanted decrease in the turbine shaft speed as both shift elements transmit the input torque. In the process the torque is transmitted to the transmission housing through internal locking.
In both cases a jerk will be felt during the shift operation.
In addition, wear in the shift elements leads to a lengthening of the shift operation. Therefore, shifting takes longer when the transmission has accumulated a higher mileage.
Control of Shift Operations With ESSC
In the automatic transmission, electronic synchronous shift control (ESSC) is used.
ESSC monitors the shift operations and is able to adapt to the wear in the shift elements over the life of the transmission.
This is possible since the shift elements are actuated by modulating valves.
The system monitors the shift time whether the shift operation is synchronous.
If the PCM detects a deviation from the stored values for the shift time and synchronization of the shift operation, the pressure buildup or reduction is adapted accordingly.