Cruise control function

P30.30-2080-71

View of instrument cluster (A1) with cruise control activated

A Illuminated segments (up to set maximum speed)

B Set target speed

C Current speed

Function requirements of the cruise control function, general

 Circuit 61 "ON" (engine running)

 CC [TPM] (cruise control) coded in central gateway control unit (N93)

 Electronic Stability Program (ESP) not deactivated

 Electronic Stability Program active (no fault)

 Vehicle speed  30 km/h

 Parking brake not applied

 Gear range "D" engaged

 CC [TPM] push button (S40 or S40/4) in the cruise control position
(LIM indicator lamp (LIMITER) off) (except code (494) USA version)

Cruise control function, general

The cruise control is integrated into the ESP control unit (N47-5) or the recuperative brake system control unit (N30/6) (with hybrid). The cruise control maintains the constant speed specified by the driver, irrespective of engine load condition and without the accelerator pedal having to be actuated.

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The signals from the CC [TPM] push button are detected by the steering column tube module (N80) and via the chassis CAN (CAN E) to the ESP control unit (N47-5) or to the RBS control unit (for HYBRID).

The set target speed is sent by the ESP control unit or by the recuperative braking system control unit (for HYBRID) via the chassis CAN and backbone CAN (CAN F) to the IC.

The requests for acceleration or deceleration (for engine control intervention) are sent by the ESP control unit or the recuperative brake system control unit (with hybrid) over the engine compartment CAN to the CDI control unit (N3/9) (with diesel engine) or to the ME-SFI [ME] control unit (N3/10) (with gasoline engine).

A switching request at the automatic transmission is transmitted from the ESP control unit or from the RBS control unit (for HYBRID) via the chassis CAN and drive train CAN (CAN C) to the EGS control unit (N15/3) (for mechanism 722.6) or to the electric controller unit (VGS) (Y3/8) (for transmission 722.9).

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Function sequence of cruise control function

The function sequence is described in the following steps:

 Function sequence for activation

 Function sequence for speed control

 Function sequence for deactivation

Function sequence for activation

Pulling out the cruise control push button, or moving it up or down, activates the cruise control starting from a vehicle speed of 30 km/h.

If the cruise control push button is moved up or down, the current vehicle speed is stored as the specified speed and either raised or lowered depending on whether the pushbutton is moved up or down.

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If the CC push button is pulled out, the last specified speed stored is applied, provided a specified speed has been stored since the last engine start. If no specified speed has been stored, the cruise control sets the current vehicle speed as the specified speed.

The CC [TPM] switch can be moved up or down to different degrees to increase or reduce the specified speed in 1 km/h or 10 km/h increments (two settings).

If the cruise control is activated, the segments around the speedometer rim are illuminated from the start of the scale up to the set maximum speed. The set target speed is marked by an orange triangle.

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Function sequence for speed control

When the vehicle is approaching the specified speed, engine power is automatically reduced. If this is not enough to prevent the vehicle exceeding the specified speed for example, on a steep downward gradient), the service brake is applied and modulated and the automatic transmission downshifted as necessary.

If the vehicle is accelerated above the specified speed (for example, when overtaking), the cruise control reapplies the specified speed after the accelerator pedal is released.

Function sequence for deactivation

The cruise control mode is deactivated if:

- The CC [TPM] switch is pushed forwards

- The CC [TPM] push button switch is pressed in the Variable Speed Limiter position to switch over
(LIM indicator lamp is lit) (except code (494) USA version)

- The brake pedal is operated.

- Parking brake is actuated

- Gear range "N" or "R" engaged

- ESP operates

- ESP switched off

- ESP deactivated (a fault)

- Vehicle speed <30 km/h

- Circuit 15 OFF (ignition OFF)