SMART Series 451 Service Manual page 58

SN_Typ 451_us.book Seite 57 Freitag, 30. November 2007 1:56 13
Automated manual transmission control unit (N15/6)
Location
The automated manual transmission control unit is
located in the passenger compartment under the
driver seat.
General
The transmission control converts the driver's
shift requests into corresponding control signals
to the clutch and the 5-speed automated manual
transmission.
This is done by relaying the shift signal about the
shift request at the electronic selector lever
module control unit over a direct line to the auto-
mated manual transmission control unit.
The automated manual transmission control unit
checks the plausibility of the shift request in
relation to the vehicle speed, the load (acceler-
ator pedal position) and the engine speed.
If the plausibility check is passed, the automated
manual transmission control unit sends the signal
to initiate the selected shift operation to the two
actuator motors for the two selector drums and to
the clutch motor to open or close the clutch.
Task
The automated manual transmission control unit
controls the following functions depending on the
input information:
• Engaging first gear at vehicle standstill
• Gear change
• Compulsory upshift just before maximum
engine speed is reached
• Compulsory downshift when engine idle speed
is approached
• Downshift for kickdown
• Disengaging the gear after 1 s when a door is
opened without the service brake or
accelerator pedal being actuated
• Crawl function
• Clutch operation
• Monitoring of clutch load
N15/6 Automated manual transmission control unit
The automated manual transmission control unit
directly reads the signals from the following compo-
nents:
• Transmission rpm sensor (L2)
• Transmission motor 1 (M17/3)
• Transmission motor 2 (M17/4)
• Clutch motor (M18)
• Electronic selector lever module control unit
(N15/5)
• Park pawl switch (S16/2)
Introduction of the smart fortwo, Model Series 451
Transmission control
P26.19-2145-00
57