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

GF40.15-P-0002P Tire Pressure Loss Warning (RDW) Function
- MODEL 203.0 /2 /7
- with CODE (477) Tire pressure loss warning up to Model Year 8

General

The tire pressure loss warning (RDW) is a system scope of the ESP and BAS control unit (N47-5). It gets by without additional components. In the event of tire pressure loss it should warn the driver before roll-flat damage occurs.

The driver is warned of pressure loss via the multifunction display (A1p13) in the instrument cluster (A1).

Function

The rolling circumference depending on the tire pressure. This dependency is evaluated by a comparison of the 4 wheel rpm in the ESP and BAS control unit (N47-5).

The ESP and BAS control unit (N47-5) compares the:
^ FL and RR wheel rpm
^ FR and RL wheel rpm

Furthermore, the following sensor signals are incorporated in the calculation at the same time:
^ Lateral acceleration
^ Yaw rate
^ Wheel torque

Aim

A tire pressure loss should be detected at a wheel before this pressure loss leads to damage to the tire.

The tires are monitored by the tire pressure loss warning without stating the position.

It is only active from a minimum speed of approx. 20 km/h.

System properties:
^ Detection of pressure loss after driving for a few minutes
^ Active when driving straight ahead, lateral acceleration ≤ 1 m/s 2
^ Active when driving at a uniform speed, 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)