MSA function, concept
During normal vehicle operation the MSA automatically switches off the engine whenever the vehicle is stationary and other salient vehicle-related conditions are satisfied.
Examples:
- Vehicle stationary
- No gear engaged
- Clutch pedal not depressed
- Engine temperature not too low
- Ambient temperature above -3 °C
- Brake vacuum sufficient
- Battery's charge status is adequate
- Driver's seatbelt is engaged
- Vehicle has not just been operated in reverse
The automatic engine shutdown is complemented by an equally automatic engine restart that is initiated as soon as the clutch pedal is depressed again, or if other demand factors are detected.
Sample scenario: The engine is switched off while the vehicle is stationary at a red light and when it comes to a halt in stop-and-go traffic.
| Item | Explanation |
|---|---|
| 1 | Vehicle moving |
| 2 | Gear is engaged. Pressure is being applied to the accelerator pedal. |
| 3 | Engine running. The time and temperature appear in the instrument cluster. |
| 4 | The driver brakes until the vehicle comes to a halt. |
| 5 | The driver engages neutral and releases the clutch pedal. |
| 6 | The engine stops. The "Start/Stop" symbol lights up in the instrument cluster. |
| 7 | The driver wishes to resume the journey. |
| 8 | The driver depresses the clutch pedal. The engine starts. |
| 9 | A gear can be engaged and the journey continued. The "Start/Stop" symbol goes out. |
IMPORTANT:
On vehicles with MSA the engine can also restart automatically without any action on the part of the driver. Irate customers and customer complaints based on this system characteristic are not signs that a malfunction is present! Samples of conditions under which a fully-automatic engine start is executed without driver action include:
- A/C request signal: For instance, in response to condensation on the windscreen.
- Low brake booster vacuum: Low brake vacuum can lead to safety risks during braking maneuvers. The engine restarts to rectify this condition.
- Engine stalls.
- Severe battery discharge: A discharged battery can lead to a vehicle breakdown. The engine restarts to rectify this condition.
- Vehicle starts moving from a stationary starting point on an incline: When the vehicle (engine) is switched off numerous systems are deactivated. Without the support supplied by various vehicle systems a rolling vehicle constitutes a safety hazard. The engine restarts to rectify this condition.