2008 Smart Fortwo 451 Technical Service & Repair Manual

• Covers the Coupe (451.331) and Cabrio (451.431) variants of the smart fortwo 451.
• M132 engine coverage explains camshaft adjustment, mechanical cup-tappet valve-clearance adjustment, belt-drive service, and cooling-system filling and bleeding.
• The second-generation 5-speed automated manual transmission (AMT 2) section features selector-drum shift-position charts, Borg-Warner synchronization, mechanical park-pawl operation, and the motor-operated dry clutch.
• Electrical sections map SAM control unit networking, CAN/LIN communication, wiring-harness groups, and diagnostic access to the vehicle's control units.
• Brake coverage addresses ESP-assisted bleeding requirements, brake-line reuse restrictions, and drum-brake adjustment. Chassis sections distinguish standard rack-and-pinion steering from optional electric power steering.
• Roof-system coverage explains Tritop soft-top operation and control, with separate descriptions of the Coupe's full roof and panoramic roof.

System Coverage and Manual Scope

Published by smart USA in 2007, this 122-page PDF documents the core mechanical and electronic architecture of the smart fortwo 451. The Introduction into Service Manual was written for personnel working in service, maintenance, repair, and aftersales.

The covered gasoline configuration uses the M132 / 132.910 engine, rated at 52 kW with 999 cc displacement, and the 717.482 transmission. Technical information reflects the September 2007 editorial cutoff. This is a vehicle-system introduction with selected service information. Detailed repair procedures and fault diagnosis are addressed through the separate Workshop Information System (WIS) and Diagnosis Assistance System (DAS); this publication receives no updates or supplements.

Engine, Fuel System, and Transmission Detail

The fuel section explains the returnless supply system, fuel distributor rail pressure regulation, and evaporative-emission control. Its leak-monitoring discussion distinguishes gross, fine, and very fine leaks and lists the conditions that enable testing. Exhaust coverage describes catalytic-converter operation, upstream and downstream oxygen sensors, and secondary air injection.

Transmission explanations follow the driver's shift request through the electronic selector lever module and transmission control unit. They describe shift-request plausibility checks, automatic and manual modes, and clutch-overload protection. Kickdown and crawl are identified among the control unit's functions. A transmission rpm-sensor illustration includes its oscilloscope signal.

Electrical Diagrams and Diagnostic Capabilities

The overall CAN/LIN network block diagram and data-flow charts for M132 injection and transmission control show how sensors, actuators, and control units exchange information. The ESP data-flow chart connects wheel-speed and motion-sensor inputs with engine and transmission intervention. These are functional network and signal-flow diagrams; a complete connector-pin wiring-diagram set is outside the publication's scope.

Diagnostic coverage addresses fault-memory access and identifies control units with programming and SCN coding capability. TAN requirements are listed for ME-SFI or SAM replacement and transmitter-key teach-in. STAR DIAGNOSIS is also referenced for maintenance-display resets and communication with the engine control unit.

For wiring repair, the manual identifies basic kit W000 589 13 99 00 and passenger-car supplement W220 589 04 99 00, with discussion of repair capability for individual wires, harnesses, and connectors.

Chassis, Body, and Service Reference Data

The suspension discussion covers the MacPherson front axle and DeDion rear axle, including front ball-joint and wheel-bearing replacement restrictions. The rear-module section illustrates how lowering the drive module improves access to the starter, alternator, and refrigerant compressor.

Body coverage includes the tridion safety cell, crash management system, and detachable Customized Bodypanel System (CBS). Bodyshell material diagrams distinguish the Coupe and Cabrio steel structures, including the Cabrio's martensitic A-pillar steel. Accompanying text addresses welding-method restrictions. The paintwork discussion identifies limits on CBS panel refinishing.

Passive-safety sections show airbag, belt-tensioner, and crash-sensor layouts. The Weight Sensing System (WSS) description explains passenger-seat classification and its role in enabling or disabling passenger restraint equipment. Climate-control coverage describes heater operation, automatic defrost-related A/C activation, and compressor shutoff conditions.

Reference material includes engine specifications, transmission oil-charge data, vehicle dimensions and loads, maintenance intervals, and Oil Service Plus information. Service-access illustrations locate maintenance points at the front and in the engine compartment, while the tire-pressure-monitor section explains restart requirements after relevant service work.

The brake notes flag excessive filling pressure as a cause of brake-system damage. Steering-wheel service notes explain how an incorrect turn-signal switch position can damage the trigger tab during removal. Brake and airbag-related work requires the factory safety precautions referenced in WIS.