GF40.15-P-0002TX Tire Pressure Loss Warning (RDW) Function

GF40.15-P-0002TX Tire pressure loss warning (RDW) function
- with CODE (477) Tire pressure loss warning

Component Identification:

General
The tire pressure loss warning (RDW) is part of the system functionality provided by the ESP control unit. It gets by without additional components In the event of tire pressure loss it should warn the driver before roll-flat damage occurs.

The multifunction display in the Instrument cluster warns the driver when pressure loss occurs. In a parallel operation the system activates the tire pressure monitor warning lamp in the instrument cluster.

Function
The rolling circumference is dependent on internal tire pressure and ground speed. Increasing ground speed and higher pressures within the tire upsize the rolling circumference. The ESP control unit assesses this dependency by comparing the 4 wheel speeds. The ESP control unit compares:
^ FL and RR wheel rpm
^ FR and RL wheel rpm

Because other dynamic response sizes, such as slip and slip angle, affect the dynamic rolling circumference while cornering affects the wheel speed, signals from the following sensors are included in the system calculations:
^ Lateral acceleration
^ Yaw rate
^ Wheel forces

Aim
Tire pressure loss warning can warn drivers when this critical situation arises. By fostering prompt use of a spare tire or TIREFIT it can help avoid permanent tire damage and maintain the tire's potential for subsequent use.

The tire pressure loss warning monitors tire condition without specifying a location.

The tire pressure loss warning assumes operation once the vehicle proceeds beyond a minimum system operating speed of roughly 20 kph.

System properties:
^ Detection of pressure loss after driving for a few minutes
^ Active in straight-ahead operation (lateral acceleration < 1 m/s2).
^ Active during uniform driving (longitudinal acceleration < 1 m/s2).
^ Inactive during control intervention function (ABS, ASR, ESP)
^ Inactive when drive torque is large
^ Inactive when braking
^ Partially active at a low coefficient of friction, on a rough road and when chains are fitted

System limits:
^ Warning limit with a pressure loss of 30 to 50% at one wheel
^ Warning without stating position
^ No detection of even diffusion losses
^ Incorrect operation by the driver (reactivation despite significantly reduced pressure)

Following modifications to wheels and tires (pressure adjustment, tire change, wheel change, etc.) it will be necessary to supply the system with correct data for the new system status. This process relies on the multifunction display in the instrument cluster and the buttons on the multifunction steering wheel.

If the vehicle is equipped with a tire pressure monitor (Code 475) the tire pressure loss warning will be deactivated in the ESP control unit.

When a new ESP control unit is installed in a vehicle with tire pressure monitor (Code 475) it is important to ensure that the tire pressure loss warning is switched off.