GF30.30-P-3001GQA Variable Speed Limiter, Function

GF30.30-P-3001GQA Variable Speed Limiter, Function
- with CODE (440) Cruise control
- except CODE (494) USA version
- as of model year 2009

Component Identification:

Function requirements of Variable Speed Limiter in general
- Circuit 61 "ON" (engine running)
- CC [TPM] (cruise control) coded in central gateway control unit (N93)
- Electronic Stability Program (ESP) active (no fault message)
- Vehicle speed ≥30 km/h
- CC [TPM] push button (S40/4) in variable speed limiter position (LIM indicator lamp (LIMITER) is lit)

Variable Speed Limiter, general
The Variable Speed Limiter (also called the variable speed limiter or SPEEDTRONIC) is an additional function of the cruise control, which is integrated in the ESP control unit (N47-5)

The Variable Speed Limiter allows the driver to set his/her own maximum speed, in a range from 30 km/h up to vehicle maximum speed.

The signals from the CC [TPM] push button switch are detected by the steering column tube module (N80) and transmitted to the ESP control unit over the engine compartment CAN (CAN C).

The selected maximum speed is transmitted by the ESP control unit over the engine compartment CAN to the instrument cluster.

Requests for acceleration or deceleration (for engine control intervention) are sent by the ESP control unit 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).

Shift requests to the automatic transmission are transmitted by the ESP control unit over the engine compartment CAN to the electric controller unit (VGS) (Y3/8).

Variable Speed Limiter, function sequence
The function sequence is described in the following steps:
^ Maximum speed function sequence
^ Activation function sequence
^ Deactivation function sequence

Maximum speed function sequence
The engine performance is reduced if the vehicle approaches the set maximum speed.
If this is inadequate, the service brake is actuated proportionately and if necessary, the automatic transmission shifts to a lower gear so that the set maximum speed is not exceeded (e.g. in case of steep declivity).

Activation function sequence
Pulling or moving the CC [TPM] switch up or down activates the Variable Speed Limiter. In this way the current vehicle speed is set as the maximum speed and moving the CC [TPM] push button switch increases or decreases it.
The CC [TPM] switch can be moved up or down to different degrees to increase or reduce the maximum speed in 1 km/h or 10 km/h increments (two settings).

If the Variable Speed Limiter is activated at a speed of <30 km/h, the maximum speed is automatically set to 30 km/h.

When the Variable Speed Limiter is activated, the segments in the electronic speedometer (A1p8) are illuminated from the beginning of the scale up to the set maximum speed.

If the CC push button is switched to the variable speed limiter, the cruise control is deactivated.

Deactivation function sequence
The Variable Speed Limiter is deactivated by:
- The CC [TPM] switch is pushed forwards
- Pressing the CC [TPM] switch induces a switchover to the cruise control (LIM indicator lamp off)
- Kickdown is activated (accelerator pedal pressed >90 % and driven speed <20 km/h away from set maximum speed)
- Circuit 15 OFF (ignition OFF)