Brake System - SMART Fortwo 451 Series Introduction Into Service Manual

General
The brake system is largely the same as the brake
system of the smart fortwo with combustion
engine in terms of its design and operation.
A new feature is the electric vacuum pump, which
is actuated by the drivetrain control unit.
Using two redundant differential pressure
sensors in the vacuum line, the drivetrain control
unit measures the pressure differential between
the vacuum in the vacuum line and the atmo-
spheric pressure. Depending on the vehicle
speed, the drivetrain control unit actuates the
brake booster vacuum pump directly via the
relays.
B64/2 Brake vacuum sensor 1
B64/3 Brake vacuum sensor 2
Introduction of smart fortwo electric drive (3rd Generation) • Model Series 451
A check valve integrated in the vacuum pump,
prevents the vacuum from being released when
the pump is switched off.
i Note
The number of operating hours of the vacuum
pump must be determined using
following intervals:
• Up to 4 years/125,000 km: every 2 years
• After 4 years/125,000 km: annually
The brake booster vacuum pump must be
replaced after 1200 operating hours. If replace-
ment is required, this is indicated by the driv-
etrain control unit.
K109 Relay for brake vacuum pump (+)
M57 Brake booster vacuum pump

Brake system

at the
DAS
P42.10-2902-00
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