Tire Pressure Module: Description and Operation

GF40.15-P-5124TR Tire pressure monitor control unit, component description
- 211 as of 1.6.05
- with CODE (475) Tire pressure monitor (Siemens)
- except CODE (494) USA version
- except CODE (498) Japan version
- 211 as of 1.7.05
- with CODE (475) Tire pressure monitor (Siemens)
- with CODE (494) USA version
- with CODE (498) Japan version
- 211
- with CODE (470) Tire pressure monitor (base)
- with CODE (494) USA version

Component Identification:

The TPM [RDK] control unit is located in the rear left-hand side of the luggage compartment on the control unit carrier Design

The TPM [RDK] control unit consists of a high frequency receiver module, a control unit circuit board with microprocessor control and an interface for the CAN data bus.

The TPM [RDK] control unit of the Siemens system is not compatible with the TPM [RDK] control unit of the Beru system.

Task
When the current tire pressure (calculated by the respective TPM wheel sensor) is compared to the stored specified pressure, the tire temperature is taken into account. The TPM [RDK] control unit calculates the valid limits for the current tire temperature.

If these limit values are dropped below, the TPM [RDK] control unit passes on an appropriate CAN signal to the instrument cluster (A1) depending on the pressure deviation. This CAN signal is processed in the instrument cluster and the relevant information is displayed to the driver via 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.

Input signals (conventional wiring):
^ Left front TPM [RDK] wheel antenna (A2/44) with code (475) Tire pressure monitor (Siemens)
^ Right front TPM [RDK] wheel antenna (A2/45) with code (475) Tire pressure monitor (Siemens)
^ Central TPM [RDK] antenna (A2/97)
^ Voltage supply (terminal 30)

The CAN-C (Controller Area Network bus class C (engine compartment)) provides a connection to:
^ Instrument cluster (A1)
^ Driver-side SAM control unit with fuse and relay module (N10/1)
^ EIS control unit (N73)
^ Central gateway control unit (N93)
^ Steering column module (N80)

The following information is processed by the TPM [RDK] control unit

Signals from the central TPM [RDK] antenna:
^ Tire pressure
^ Temperature
^ Acceleration and status ID

Signals from the instrument cluster:
^ Initialization (Function test, establishment of a checked initial status)
^ Vehicle speed signal

Signals from driver-side SAM control unit with fuse and relay module:
^ Outside air temperatures
^ Circuit 61 "ON" (to detect "engine running")

Signals from EIS [EZS] control unit:
^ Wheel speeds
^ Terminal 15 "ON"

Signals from central gateway control unit:
^ Country code
^ Engine/body variant
^ Diagnosis active

Signal from steering column module:
^ Steering angle signal