Attention! The RDC system cannot warn of sudden and severe tire damage or rupture due to external factors.
The tire pressure monitoring system (RDC) or tire damage control system (RPA) monitors the pressure in all four wheels while the car is moving. If the pressure in one or more tires drops, an indicator lights up on the instrument panel, which informs that the pressure in the tire(s) is noticeably dropping. The pressure standards (1 bar = 1 kgf/cm²) of air in the tires are given on the plate attached to the end of the driver's door (Fig. 1.58) and are specified at normal temperature for tires recommended by BMW.
When driving with a trailer, you must be guided by the figures given for the maximum loaded vehicle.
When checking the tire pressure, do not forget about the spare or compact wheel, the pressure in it should be 4.2 bar. Checking the tire pressure should be done some time after its adjustment, to allow the processes in the pumped air to proceed.
Attention! It is necessary to check the tire pressure regularly at least twice a month, and always before a long trip.
When installing tires of a different size and brand, the pressure may not correspond to the table value. The compact wheel does not have an RDC system sensor.
Incorrect tire pressure has a negative impact on vehicle handling, increases the risk of tire damage, shortens their service life and can cause an accident. In order for the RDC system to remember the correct pressure values, it is necessary to check the air pressure in the tires of all wheels using the device (pressure gauge) and compare them with the table values and, if necessary, adjust it. Now you can turn on the RDC system. The RDC system must be turned on in the following order:
- check and adjust tire pressure;
- turn the ignition key to position "2", start the engine, but do not move;
- press the button (Fig. 1.59) and hold it down until the system indicator on the instrument panel lights up yellow for a few seconds;
- start moving.
Release the key. After a few minutes of driving, the RDC system will remember the tire pressure readings and accept them as a program value.
If the tire pressure has been adjusted, it is necessary to repeat the procedure for memorizing it by the RDC system, and the system is turned on automatically when the ignition key is set to position "2" and the system is always in working order while driving.
If the pressure in one or more tires drops, a yellow indicator lights up on the instrument panel and a message appears on the display of the automatic diagnostic system "Check Tyre Pressure" ("Check tire pressure").
Sometimes the requirement to check the pressure appears soon after it has been corrected. This means that the tires were over- or under-inflated during the correction. It is necessary to check the pressure again, bring it up to the norm and turn on the RDC system again.
If the tire is damaged (sudden pressure release), the yellow indicator on the instrument panel lights up, a message appears on the display of the automatic diagnostic system "Tyre Defect" ("Tire damage") and a beep sounds.
In such circumstances it is necessary:
- take your foot off the gas pedal;
- if road conditions permit, do not use the brake pedal or use it with extreme caution;
- steer the car, avoiding sudden movements of the steering wheel;
- reduce speed until the car comes to a complete stop;
- replace the damaged wheel.
It is important to remember that the RDC system may experience interference from other systems and devices operating on its frequency. During interference, a yellow indicator lights up on the instrument panel and a message appears on the automatic diagnostics display - "Tyre Control Inactive" ("There is no tire pressure monitoring"). Similar information is received:
- in case of system failure;
- if one of the wheels does not have an RDC system unit;
- if there are other wheels with RDC system unit in the car, not counting the spare wheel;
- after using non-standard RDC system blocks on wheels (exchange of information on a different frequency). Memorizing new identification numbers takes several minutes, only after which the system is able to react to a drop in tire pressure and notify about it.