Keyless Starting System: Description and Operation

General Description for Start/Stop System

Additional information:

• => Owner's Manual

• 426 2009 Start/Stop System

•

General Information

The Start/Stop System reduces fuel consumption by turning off the engine when the vehicle is at a standstill and turning the engine back on when the driver starts to drive. The Stop/Start System works automatically when the vehicle is driven for approximately four seconds at a minimum of 3 km/h.

DTC recognition and display

The software in the engine control module (J623) controls the Start/Stop System.

The engine control module (J623) is equipped with OBD.

Use Vehicle diagnostic tester "Guided Fault Finding".

Battery recharging or battery jump start terminal on vehicles with the start/stop system

First connect the positive terminals to a charging cable and then connect the vehicle body ground. This ensures that the battery monitoring control module (J367) is not bridged. Charging the battery directly on the negative terminal bridges the battery monitoring control module (J367) and prevents the battery monitoring control module (J367) from recording the battery data during the charging process. The values stored in the data bus on board diagnostic interface (J533) regarding the battery condition no longer match the values for the charged battery (A).

Replacing the battery (A) on a vehicle with the start/stop system

Vehicles with a start/stop system only have an AGM battery as the starter battery instead of the typical lead battery due to its higher cycle life.

Refer to the => Parts Catalog for the correct part names. The components of the Stop/Start System do not have a special markings and look the same as the other components from the outside.

The following parts comprise the start-stop system:

• Battery (A)

• Generator (C)

• Voltage regulator (C1)

• Starter (B)

• Brake lamp switch (F)

• Clutch pedal switch (F36)

• Start/Stop mode button (E693) => [ Start/Stop Mode Button (E693), Removing and Installing ] Start/Stop Mode Button (E693), Removing and Installing

• Engine Coolant Temperature (ECT) Sensor (G62)

• Accelerator pedal position sensor (G79)

• Transmission neutral position sensor (G701)

• ABS Control Module (J104)

• Climatronic control module (J255)

• Control module with display unit in instrument cluster (J285) => [ Instrument Cluster Overview ] Instrument Cluster Overview

• Battery Monitoring Control Module (J367)

• Power steering control module (J500)

• Vehicle electrical system control module (J519) => [ Vehicle Electrical System Control Module (J519) ] Initial Inspection and Diagnostic Overview

• Voltage stabilizer (J532) => [ Voltage Stabilizer (J532), Removing and Installing ] Voltage Stabilizer (J532), Removing and Installing

• Data bus on board diagnostic interface (J533) => [ Data Bus On Board Diagnostic Interface (J533) ] Initial Inspection and Diagnostic Overview

• Engine Control Module (J623)