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Electrical system
On board electrical system/power supply
General
The on board electrical system ensures that the power supply to all the electrical consumers and components in the vehicle is appropriate for the requirements and the situation. The on board electrical system consists of the following main components: Starter Battery Alternator ME SFI [ME] control unit (gasoline engines) CDI control unit (diesel) • Instrument cluster • • • • Battery The battery supplies the consumers when the engine is off, the starter while the engine is being started, and the on board electrical system when the alter nator is unable to provide the required consumer current. The battery is located in the passenger footwell under the carpeting. Battery variants: • 42 Ah for gasoline engines • 61 Ah for diesel engines
Starter
The starter supplies the torque required to start the engine. It takes the necessary energy from the adequately charged battery. Starter variants: • 0.95 kW for gasoline engines • 1.00 kW for diesel engines
P54.10-2271-00
G1
Battery
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Introduction of the smart fortwo, Model Series 451
– This printout will not be recorded by the update service. Status: 03 / 2007 –
On board electrical system/power supply
Alternator
The alternator supplies the electrical consumers while the engine is running and recharges the battery so that a subsequent engine start is possible. The alternator is equipped with an overvoltage protection function that limits the on board power supply voltage in the event of a defect in the governor. The alternator is monitored by the ME SFI control unit (gasoline engine) or CDI control unit (diesel engine). Gasoline engine: The alternator is pre excited via a direct line. The alternator load is reported back to the ME SFI control unit over a separate line and monitored. Diesel engine: The CDI control unit specifies a regulation voltage for the alternator over LIN A. This allows the load to be influenced within limits. In the other direction the alternator reports its operating rate back to the control unit.
Instrument cluster
The on board power supply voltage is monitored by the engine control. If the voltage is < 11.5 V for a period of 3 min, a signal is sent over CAN to the instrument cluster and the battery indicator lamp lights up.
P54.10-2783-00
Shown on diesel engine
G2
Alternator
Introduction of the smart fortwo, Model Series 451
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Electrical system
Electrical system
Overall network
Overall network location of components
P00.19-3887-00
Overall network full equipment
A1 A15p4
B24/15 B32
Instrument cluster on the left side of the instrument panel Tachometer (with code (V31) Cockpit clock and ta chometer package) in the center of the instrument panel Yaw rate and lateral acceleration sensor under the floor covering near the left seat ATA [EDW] microwave sensor (with code (V01) Anti theft alarm system) under the center console near the hand brake lever
B38
G2 H3/2
N2/7 N3/9 N3/10 N10/10
Rain sensor/light sensor (with code (V54) Rain/light sensor) in the middle of the windshield near the in side rearview mirror Alternator on the right side of the engine at the rear Alarm siren with inclination sensor (with code (V01) Anti theft alarm system) on the right in front of the fuel tank Restraint systems control unit in the center under the instrument panel CDI control unit (diesel) behind the right side paneling in the rear ME SFI [ME] control unit (gasoline) behind the right side paneling in the rear SAM control unit on the left under the instrument panel
(Legend continued on the next page)
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Introduction of the smart fortwo, Model Series 451
– This printout will not be recorded by the update service. Status: 03 / 2007 –
Overall network
Overall network CAN bus/LIN bus
P00.19-3875-00
Block diagram full equipment
N14/2
N15/6
N23
N25/5
N47 5
N49
Glow output stage on the right side of the frame type inte gral support at the rear under the center console Automated manual transmission control unit under the floor covering near the driver seat Heater/AC operating unit (with code (I01) Air conditioning Plus and code (V30) Outside temperature sensor (FFO)) in the center of the instrument panel Front HS [SIH] control unit (with code (S17) Seat heaters (FFO)) in the center under the instrument panel ESP control unit on the outside of the floor panel near the driver seat Steering angle sensor on the steering column under the steering wheel
N57/2
N68
X11/4
Power window convenience feature control unit (with code (V43) Power windows) on the left under the instrument panel Steering assist control unit (with code (V26) Power steering, EPS (FFO)) near the steering gear Data link connector on the bottom of the instrument panel on the driver side Controller Area Network (data bus/CAN bus) CDI local interconnect network Interior local interconnect network 1 Interior local interconnect network 2
CAN LIN A LIN B LIN C
Introduction of the smart fortwo, Model Series 451
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Electrical system
Electrical system
Wiring harnesses
P54.18 4135 00
Wiring harness groups
The wiring harness is divided into the following groups: 1 Main wiring harness 2 Engine wiring harness 3 Transmission wiring harness 4 Battery wiring harness
Not illustrated: Door wiring harness Soft top wiring harness (in smart fortwo cabrio) Rear panel wiring harness
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Introduction of the smart fortwo, Model Series 451
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Wiring harnesses
General
The wiring harness variants result from the basic standard equipment, the special equipment items and the national versions.
Repair capability
A wiring harness repair kit in a case is available for repairing individual lines, wiring harnesses and connectors without sealed plugs. All the above repairs can be carried out using this kit. It is also possible to expand the kit with a supple mental repair set to allow wiring harnesses with sealed plugs to be repaired.
i Note Supplemental information on the wiring harness repair kit can be found in the special tools chapter.
P54.18-4140-00
Wiring harness repair kit
Introduction of the smart fortwo, Model Series 451
– This printout will not be recorded by the update service. Status: 03 / 2007 –
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Electrical system
Electrical system
Diagnosis
General
The network architecture in model 451 allows external access to individual control units in the CAN bus system.
Diagnostic tester
By connecting the diagnostic tester, the vehicle and all its equipment variants can be precisely identi fied. This enables accurate fault evaluation and rectification and the analysis of vehicle specific values and parameters.
Data link connector
The CAN bus is accessed by means of a diagnostic tester that is connected to the vehicle via the data link connector. The data link connector is linked directly to the CAN bus and can therefore access all the control units that have diagnostic or program ming capability. The data link connector is located in the vehicle interior on the underside of the instru ment panel on the driver side.
P54.22-2084-00
Location of data link connector (X11/4)
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Introduction of the smart fortwo, Model Series 451
– This printout will not be recorded by the update service. Status: 03 / 2007 –
Diagnosis
Diagnosis capability
The following control units have diagnosis capa bility: • • • • • • • • • Instrument cluster Restraint systems control unit CDI control unit ME SFI [ME] control unit SAM control unit Automated manual transmission control unit Heater/AC operating unit ESP control unit Steering assist control unit
TAN generator
For the following applications a TAN (transaction number) must be generated. The process for this is familiar from the other smart model series: • • • • • Retrofitting of softouch Retrofitting of steering wheel gearshift Replacement of engine control unit Replacement of SAM control unit Teach in of vehicle keys (after loss or detection of additional vehicle keys)
Fault memory Each of the control units listed above has a fault memory that provides information about the associ ated systems. The stored faults are displayed by the diagnostic tester and must be rectified. When all the faults have been eliminates, the fault memory must be erased and read out again. There should be no fault entries left afterwards. Maintenance intervals The diagnostic tester is used to reset the mainte nance interval in the instrument cluster following an Oil Service Plus or a maintenance service.
i Note Up to eight vehicle keys in total can be taught in at the same time.
SCN (Software Calibration Number) coding
The following control units can be coded via the SCN coding process: • • • • • • • CDI control unit*) ME SFI [ME] control unit*) SAM control unit ESP control unit Automated manual transmission control unit*) Restraint systems control unit Instrument cluster
Programming control units
The following control units can be programmed: • • • • • CDI control unit ME SFI [ME] control unit SAM control unit Automated manual transmission control unit ESP control unit
*) The control unit is relevant to exhaust emissions, i.e. the SCN is written in the control unit and can be interrogated. For the other control units a virtual SCN is generated during the coding process, but this is not written to the control unit.
Introduction of the smart fortwo, Model Series 451
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Electrical system
Electrical system
SAM control unit
All the fuses in model 451 are accommodated on the SAM control unit. Fuses 1 31 are located on the front of the SAM control unit; fuses 32 35 are located on the rear. The SAM control unit is installed in the vehicle inte rior on the left side near the A pillar under the instrument panel. The SAM control unit is linked with the CAN in order to exchange data. It communicates with the following components: • • • • • • • • • • Instrument cluster ESP control unit Restraint systems control unit CDI control unit ME SFI [ME] control unit Heater/AC operating unit Steering assist control unit Yaw rate and lateral acceleration sensor Steering angle sensor Data link connector
P54.21-2702-00
SAM control unit (front)
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Introduction of the smart fortwo, Model Series 451
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SAM control unit
The SAM control unit also communicates over: • LIN B with the tachometer and the rain sensor/light sensor • LIN C with the ATA microwave sensor and the alarm siren with inclination sensor. The relay and fuse box with all the relays and fuses is integrated in the SAM control unit.
i Note Up to eight vehicle keys can be stored in the SAM control unit.
P54.21-2703-00
SAM control unit (rear)
Introduction of the smart fortwo, Model Series 451
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Electrical system