Tire pressure monitor function - GF40.15-P-0001SXU

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

Location of components shown on model 221.056 with engine 272

Fig 1: Identifying Tire Pressure Monitor Components Location

Courtesy of MERCEDES-BENZ USA

The tire pressure monitoring system (TPM) permanently monitors the tire inflation pressures.

The tire inflation pressure and tire temperature are measured in the tire at regular intervals and transmitted, in part telemetrically, to a TPM [RDK] control unit via an HF transmission path.

The TPM system assists the driver with monitoring the correct tire inflation pressure and thus serves the purpose of active safety. Via the multifunction display (A1p13) in the instrument cluster the driver is informed about the current tire inflation pressure or about the necessary corrections to the tire inflation pressure and about flat tires.

The TPM system acts as a preventive measure in the following situations:

"Tire bursts" due to excessive flexing energy, triggered by driving quickly with too low air pressure.
The driver is requested to check the tire inflation pressure.
A timely warning is issued in the event of a rapid pressure drop that is greater than 0.2 bar/min.

A sudden pressure loss cannot be detected due to the system design.

Regular checking of the tire inflation pressure is simplified by the TPM system.

Tire wear and fuel consumption are reduced by having the correct tire pressure.

The TPM system does not relieve the driver of a regular manual check of the tire inflation pressure (at least every 14 days). Here the table in the fuel filler flap should be drawn on to set the correct tire inflation pressure. The TPM system does not warn against an incorrectly adjusted tire inflation pressure.

The TPM system consists of the following components:

Left front TPM [RDK] wheel sensor
Right front TPM [RDK] wheel sensor
Left rear TPM [RDK] wheel sensor
Right rear TPM [RDK] wheel sensor
Central TPM [RDK] antenna
TPM [RDK] control unit
Left multifunction steering wheel button group
Right multifunction steering wheel button group

The wheel sensors are attached to the metal valves in the rims, not visible from outside and measure the air pressure as well as the temperature of the tire.

The data transmitted by the wheel sensors, in combination with an ID (individual serial number), are received via the central TPM antenna and reach the TPM [RDK] control unit via a discreet line.

The ID serves to detect the wheels fitted to the vehicle.

In the TPM [RDK] control unit the air pressure, set and activated by the driver, of each wheel is stored as the specified pressure to be monitored.

The data evaluated by the TPM [RDK] control unit is displayed in the multifunction display of the instrument cluster in the form of messages relevant to function and operation.

Tire pressure monitor (RDK) activation	GF40.15-P-0001-02SXU
Tire pressure monitor (RDK), displaying tire inflation pressure	GF40.15-P-0001-03SXU
Tire pressure monitor (TPM), messages relevant to the function	GF40.15-P-0001-04SX
Tire pressure monitor (TPM), messages relevant to operation	GF40.15-P-0001-05SXU
Detection of pressure loss, function	GF40.15-P-2005SXA