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Home >> BMW >> 2013 >> 335is 2D Coupe, Standard Trans >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Engine Performance - Functional Description - E92 >> Engine Performance - Functional Description >> Automatic Engine Start-Stop Function (MSA) >> Brake vacuum sensor, manual transmission
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Brake vacuum sensor, manual transmission

The brake servo is equipped with a brake vacuum sensor for ensuring brake power assistance even when the engine is switched off. The brake vacuum sensor is located next to the brake servo. The brake vacuum sensor is connected over a separate line.

When the vacuum falls below a specified range the system executes an automatic engine start to generate the required vacuum.

Fig 1: Identifying Brake Vacuum Sensor
G09871543Courtesy of BMW OF NORTH AMERICA, INC.
Item Explanation
1 Brake vacuum sensor
2 two-pin plug connection

The brake vacuum sensor gives out voltage signals, depending on the vacuum present in the engine control unit.

Fig 2: Brake Vacuum Sensor Characteristic Graph
G09871544Courtesy of BMW OF NORTH AMERICA, INC.
Item Explanation
1 Voltage
2 Pressure
3 Brake vacuum sensor signal shape
NOTE: Installation of the brake vacuum sensor depending on the engine version and transmission version
Installation of the brake vacuum sensor depending on the engine version and transmission version. For vehicles without brake vacuum sensor, the vacuum will be determined in the engine control unit based on characteristic curve calculations.