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Home >> Mercedes Benz >> 2008 >> GL450 4WD >> Repair and Diagnosis >> Electrical >> Motors, Switches, Relays >> Charging, Control Panel/Cluster, Data Bus, Fuses/ Relays, PARKTRONIC, Sensors & Switches - 164 Chassis >> Basic Knowledge >> Upper control panel control module component description - GF54.21-P-6040GZU

Upper control panel control module component description - GF54.21-P-6040GZU

MODEL 164.1 /8 with CODE (489) Airmatic (air suspension with level adjustment and adaptive damping system ADS) with CODE (430) Offroad package with CODE (494) USA version 

Shown on model 164.1 

Fig 1: Identifying Upper Control Panel Control Unit - Shown On Model 164.1
G05259001Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Location 

The upper control panel control unit is located in the center console.

Task 

Scanning the following switches: 

Reading in the following function indicator lamps: 

Voltage supply and reading in of data: 

Function 

ESP OFF switch 

The ESP Off switch can be used to switch the anti-slip control of the "Electronic Stability Program" on and off. The function requirements for this switch is circuit 15 "ON". The function of the ESP systems is indicated in the instrument cluster (A1).

PTS OFF switch 

The Parktronic system is activated or deactivated via the PTS OFF switch. If the switch is actuated, the upper control panel control unit sends a signal to the PTS control unit (N62) via CAN-B. The PTS control unit then sends a message requesting actuation of the status LED in the PTS OFF switch back to the upper control panel control unit.

Left front HS [SIH] switch and right front HS [SIH] switch 

The heated seats have 3 stages. One-time actuation of the SIH switch activates stage 3 of the heated seats (all 3 red LEDs light up). Further actuations switch to stage 2 (the two lower LEDs go on), to stage 1 (the lowest LED goes on), or the heated seats are switched off (no function indicator). The function requirements for this switch is circuit 15R "ON". Each press of the left front HS [SIH] switch and right front HS [SIH] switch is sent by the upper control panel control unit over the CAN-B.

Comfort/Sport switch (ADS) 

The driver can program the damping level as desired using the Comfort/Sport switch (ADS):

  1. "AUTO"  Skyhook mode
  2. "SPORT"  Firm damping
  3. "COMFORT"  Soft damping

In the "SPORT" setting the upper LED goes on and for the "COMFORT" setting the lower LED goes on. If the vehicle is in the "AUTO" mode nothing is displayed in the Comfort/Sport switch (ADS).

Transmission mode switch 

Pressing the transmission mode switch enables the driver to choose between a comfort-oriented and a sporty transmission program. The transmission mode switch is read in by the upper control panel control unit and sent to the CAN-B. The central gateway control unit (N93) reads in this message and then sends it over the CAN-C to the fully integrated transmission control (VGS) control unit (Y3/8n4). Each respective transmission program is selected in the fully integrated transmission control (VGS) control unit.

The function requirements for this switch is circuit 15R "ON".

Hazard warning system switch 

Pressing the hazard warning system switch wakes-up the upper control panel control unit from its "Sleep mode" and the hazard warning system function is activated. The message is sent cyclically (every 100 ms) until the function is deactivated by pressing the hazard warning system switch again. The flashing function illumination of the hazard warning system switch is triggered by the CAN message of the rear SAM control unit (N10/8). There is no faster flashing of a defective indicator lamp for the hazard warning flasher system. As soon as the hazard warning flasher function is activated the switch and controls illumination for the hazard warning system switch is switched off. The function illumination of the hazard warning system is not dimmed.

IMPORTANT The selected function is confirmed when the indicator lamps (LEDs) light up. The pulse to light up is sent by each respective control unit.

Discrete inputs: 

Discrete outputs: 

Voltage limit: 

The operating voltage is between 12 and 14 V.