2010 Mercedes GL-Class Owner's Manual - Page 242

240 Tires and wheels illuminated, the system may not be able to detect or signal low tire pressure as intended. TPMS malfunctions may occur for a variety of reasons, including the installation of incompatible replacement or alternate tires or wheels on the vehicle that prevent the TPMS from functioning properly. Always check the TPMS malfunction telltale after replacing one or more tires or wheels on your vehicle to ensure that the replacement or alternate tires and wheels allow the TPMS to continue to function properly. Example illustration i If a condition causing the TPMS to malfunction develops, it may take up to 10 minutes for the system to signal a malfunction using the TPMS telltale flashing and illumination sequence. The telltale extinguishes after a few minutes driving if the malfunction has been corrected. Tire pressure inquiries are made using the multifunction display. The current tire inflation pressure for each tire appears in the multifunction display after a few minutes of driving. i Possible differences between the readings of a tire pressure gauge of an air hose, e.g. gas station equipment, and the vehicle's control system can occur. The tire pressure displayed by the control system apply to sea level. In high-altitude locations, the reading on a tire pressure gauge will be higher than the reading issued by the vehicle's control system. Do not reduce the tire inflation pressure under such circumstances. X X When the vehicle has been parked for longer than 20 minutes, the message Tire pressure displayed after driving for a few minutes. appears in the multifunction display. The TPMS recognizes new wheels or sensors automatically after the learn-in phase. As long as the tire inflation pressure values cannot be allocated to the individual wheels, the message Tire Pressure Monitor Active appears. Despite this message, the tire inflation pressure values are monitored already. Operation i With a spare wheel mounted, the system may still indicate the tire inflation pressure of the removed road wheel for some minutes. If this happens, keep in mind that the indicated value where the spare wheel is mounted does not reflect the actual spare tire inflation pressure. i Operating radio transmission equipment (e.g. wireless headsets, two-way radios) in or near the vehicle could cause the TPMS to malfunction. i This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: 1. This device may not cause harmful interference, and 2. this device must accept any interference received, including interference that may cause undesired. Any unauthorized modification to this device could void the user's authority to operate the equipment. Switch on the ignition. Press button V or U on the multifunction steering wheel repeatedly until the standard display appears in the multifunction display (Y page 128). X Press button & or * until the current inflation pressure for each tire appears in the multifunction display.