Mercedes-Benz GL-Class: Important safety notes - Tire pressure monitor (USA only) - Tire pressure - Wheels and tires - Mercedes-Benz GL-Class Owner's ManualMercedes-Benz GL-Class: Important safety notes

If a tire pressure monitor system is installed, the vehicle's wheels have sensors that monitor the tire pressures in all four tires. The tire pressure monitor warns you when the pressure drops in one or more of the tires. The tire pressure monitor only functions if the correct wheel electronics units are installed on all wheels.

The tire pressure monitor has a yellow warning lamp in the instrument cluster for indicating pressure loss or a malfunction.

Whether the warning lamp flashes or lights up indicates whether a tire pressure is too low or the tire pressure monitoring system is malfunctioning:

if the warning lamp is lit continuously, the tire pressure on one or more tires is significantly too low. The tire pressure monitor is not malfunctioning.

if the warning lamp flashes for 60 seconds and then remains lit constantly, the tire pressure monitor is malfunctioning.

WARNING Each tire, including the spare (if provided), 
Each tire, including the spare (if provided), should be checked at least once a month when cold and inflated to the pressure recommended by the vehicle manufacturer on the tire and Loading Information placard on the driver's door B-pillar or the tire pressure label on the inside of the fuel filler flap. If your vehicle has tires of a different size than the size indicated on the tire and Loading Information placard or the tire pressure label, you should determine the proper tire pressure for those tires.
As an added safety feature, your vehicle has been equipped with a tire pressure monitoring system (TPMS) that illuminates a low tire pressure telltale when one or more of your tires are significantly underinflated.
Accordingly, when the low tire pressure telltale illuminates, you should stop and check your tires as soon as possible, and inflate them to the proper pressure. Driving on a significantly underinflated tire causes the tire to overheat and can lead to tire failure.
Underinflation also reduces fuel efficiency and tire tread life, and may affect the vehicle's handling and stopping ability.
Please note that the TPMS is not a substitute for proper tire maintenance, and it is the driver's responsibility to maintain correct tire pressure, even if underinflation has not reached the level to trigger illumination of the TPMS low tire pressure telltale.
Your vehicle has also been equipped with a TPMS malfunction indicator to indicate when the system is not operating properly. The TPMS malfunction indicator is combined with the low tire pressure telltale. When the system detects a malfunction, the telltale will flash for approximately one minute and then remain continuously illuminated. This sequence will be repeated every time the vehicle is started as long as the malfunction exists.
When the malfunction indicator is 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 mounting 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.

malfunctioning, it may take more than If the tire pressure monitor is malfunctioning, it may take more than 10 minutes for the tire pressure warning lamp to inform you of the malfunction by flashing for 60 seconds and then remaining lit.

When the malfunction has been rectified, the tire pressure warning lamp goes out after driving for a few minutes.

Information on tire pressures is displayed in the multifunction display. After a few minutes of driving, the current tire pressure of each tire is shown in the multifunction display.

on-board computer may differ from those The tire pressure values indicated by the on-board computer may differ from those measured at a gas station with a pressure gauge. The tire pressures shown by the onboard computer refer to those measured at sea level. At high altitudes, the tire pressure values indicated by a pressure gauge are higher than those shown by the on-board computer. In this case, do not reduce the tire pressures.

can be affected by interference from radio The operation of the tire pressure monitor can be affected by interference from radio transmitting equipment (e.g. radio headphones, two-way radios) that may be being operated in or near the vehicle.

FCC Rules. Operation is subject to the 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 operation.

Any unauthorized modification to this device could void the user’s authority to operate the equipment.

    Checking tire pressure electronically
    ► Make sure that the SmartKey is in position 2 in the ignition lock. ► Press and hold the button on the multifunction steering wheel until the standard display appears in the mu ...

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