Powertrain Management: Description and Operation

EGS System:

PURPOSE
The Electronic Transmission Control (EGS) system of the A4S 310 R transmission replaces previous "hydraulic only controls" which provides smooth, precise control of shift points and utilizes programed control capabilities for increased economy, comfort and safety.

OPERATION
The EGS control unit receives input variables such as engine speed, output speed, injection signal, throttle (accelerator pedal) position, kick-down switch, drive program and selector lever position. The control unit program processes this information sends shift pulses for upshifts and downshifts to the transmission valve body (solenoid valves, modulation pressure) and decides upon the corresponding torque converter lockup clutch engagement. The transmission control unit communicates with the following components:

- Gear selector lever switch: L1, L2, L3, L4
- Program switch: A, M
- Instrument cluster
- Kick-down switch
- Brake light switch (with P/N shift-lock only)
- Brake light test switch (with P/N shift-lock only)
- Lifting solenoid P/N shift-lock (with P/N shift-lock only)
- Solenoid valves: MV 1, MV 2, MV band, MV-WK
- Oil sump temperature sensor
- Pressure regulator
- Vehicle speed sensor
- DME control unit

Driving Modes
Selective driving modes allow the operator to choose different performance characterics to fit individual driving habits and changing road condition.

Economy - designed to provide low fuel consumption. Fourth gear is provided with torque converter lockup to reduce engine speed and prevent torque converter slippage.

NOTE: The economy mode is selected automatically whenever the engine is started.

Sport - designed to provide more performance by delaying the upshifts until a higher rpm range.

Manual - allows the transmission to be locked into a selected gear and will not upshift.

Fail-safe
The EGS transmission has an emergency driving program in case of certain electrical faults. This allows the vehicle to be driven to the workshop and notifies the driver of a problem through the check control display on the instrument cluster.