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Home >> Mercedes Benz >> 2011 >> CL65 >> Repair and Diagnosis >> Suspension >> Wheels & Tire System >> Tires, Wheels & Chassis Alignment -- 216.379 Cl65 AMG >> Basic Knowledge >> Tire pressure monitor control unit, component description - GF40.15-P-5124SX

Tire pressure monitor control unit, component description - GF40.15-P-5124SX

MODEL 216.3, 221.0 /1 with CODE (475) Tire pressure monitor (Siemens) up to Model Year 8 

MODEL 216.3, 221.0 /1 with CODE (470) Tire pressure monitor (base) up to Model Year 8 

MODEL 216.3 with CODE (494) USA version up to Model Year 8 

shown on model 221 

Fig 1: Identifying TPM (RDK) Control Unit (Shown On Model 221)
G07510721Courtesy of MERCEDES-BENZ USA

Location 

The TPM [RDK] control unit is located in the passenger footwell.

Design 

The TPM [RDK] control unit consists of a HF-receiver module, a control unit circuit board with microprocessor control and an interface for the Controller Area Network (data bus/CAN Bus) CAN data bus.

Task 

Tire temperature is taken into account in the comparison of the tire pressure currently determined by the respective sensor with the stored specified pressure. The TPM [RDK] control unit calculates the valid limits for the current tire temperature.

If these limit values are dropped below, then depending on the pressure deviation the TPM [RDK] control unit passes on a corresponding CAN signal to the instrument cluster (A1). This CAN signal is processed in the instrument cluster and the appropriate information is displayed for the driver on the multifunction display (A1p13). The TPM [RDK] control unit also constantly monitors all input and output signals for faults. Detected faults that are relevant to function are entered into the fault memory.

The tire pressure monitoring system control unit receives information from the following sensors via a radio frequency (RF) line from the tire pressure monitoring system antenna (A2/97):

On vehicles with the code (475) Tire pressure monitor (Siemens) the TPM [RDK] control unit is connected to the following components via the local interconnect network (LIN):

Upon request from the TPM [RDK] control unit the wheel antenna transmit in sequence a trigger signal to the respective wheel sensor. The wheel sensors then transmit a transmission protocol to the TPM [RDK] via the central TPM [RDK] antenna. These transmission protocols are required for wheel sensor determination after system activation.

In system operation the wheel sensors automatically send the transmission logs at specific intervals.

The transmission logs also contain the following data:

Via the Controller Area Network (data bus/CAN bus) (CAN) a data exchange takes place with the following control units and controls:

IMPORTANT The central gateway control unit forms the interface between the interior CAN, the chassis CAN and the central CAN.

The following information from other systems is processed here:

SAM control unit with fuse and relay module 

EIS [EZS] control unit 

CDI control unit (model 221.0/1 with engine 629 or engine 642) 

ME-SFI [ME] control unit (model 216.3, model 221.0/1 except engine 629 or engine 642) 

Steering column module 

ESP control unit 

Central gateway control unit 

The following information is issued to other systems:

Instrument cluster 

Central gateway control unit 

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