lights MERCEDES-BENZ GLS 2017 Repair Manual

Important safety notes
G WARNIN G
Eac h tire, includin g th e spar e (if provided),
should be checke d at least once a month
when cold and inflated to th e pressur e rec -
ommended by th e vehicl e manufacturer on
th e Tir e and Loading Information placard on
th e driver' s door B-pillar or th e tire pressur e
label on th e inside of th e fuel filler flap . If your
vehicl e has tires of a differen t siz e than th e
siz e indicated on th e Tir e and Loading Infor -
mation placard or th e tire pressur e label, you
should determine th e proper tire pressur e for
those tires .
As an added safet y feature, your vehicl e has
been equipped wit h a tire pressur e monitoring
system (TPMS) that illuminate s a low tire pres-
sur e telltale when on e or mor e of your tires
are significantly underinflated. Accordingly,
when th e low tire pressur e telltale illuminates,
you should stop and chec k your tires as soo n
as possible , and inflat e them to th e proper
pressure. Drivin g on a significantly underin-
flated tire causes th e tire to overheat and can
lead to tire failure. Underinflation also
reduce s fuel efficiency and tire tread life , and
may affec t th e vehicle's handlin g and stop-
pin g ability.
Pleas e note that th e TPM S is no t a substitut e
for proper tire maintenance
, a nd it is th e d riv -
er' s responsibilit y to maintai n correc t tire
pressure, eve n if underinflation has no t
reached th e level to trigge r illumination of th e
TPM S low tire pressur e telltale.
US A only:
Your vehicl e has also been equipped wit h a
TPM S malfunction indicator to indicat e if th e
system is no t operating properly. The TPM S
malfunction indicator is combined wit h th e
low tire pressur e telltale. When th e system
detects a malfunction , th e warning lamp will
flas h for approximately a minute and then
remain continuously illuminated. This
sequenc e will be repeated every time th e vehi-
cle is started as lon g as th e malfunction
exists. When th e malfunction indicator is illuminated,
th e system may no t be able to detec t or signal
low tire pressur e as intended. TPM S malfunc -
tion s may occur for a variet y of reasons,
includin g th e mounting of incompatible
replacemen t or alternate tires or wheels on
th e vehicl e that preven t th e TPM S from func-
tioning properly. Always chec k th e TPM S mal-
function telltale after replacing on e or mor e
tires or wheels on your vehicl e to ensur e that
th e replacemen t or alternate tires and wheels
allow th e TPM S to continue to function prop-
erly.
It is th e driver' s responsibilit y to set th e tire
pressur e to that recommended for cold tires
whic h is suitable for th e operating situation
( Y
page 349). Not e that th e correc t tire pressur e
for th e curren t operating situation must first be
taught-in to th e tire pressur e monitor. If there is
a substantial loss of pressure, th e warning
threshold for th e warning message is aligned to
th e referenc e value s taught-in . Restart th e tire
pressur e monitor after adjusting th e pressur e of
th e cold tires ( Y
page 355). The curren t pres-
sures are saved as ne w referenc e values. As a
result , a warning message will appear if th e tire
pressur e d rops significantly.
T he tire pressur e monitor does no t warn you of
an incorrectl y set tire pressure. Observ e th e
note s on th e recommended tire pressur e
( Y
page 349).
The tire pressur e monitor is no t able to warn you
of a sudde n loss of pressure, e.g. if th e tire is
penetrated by a foreign object. In th e event of a
sudde n loss of pressure, brin g th e vehicl e to a
halt by braking carefully. Avoid abrup t steering
movements.
The tire pressur e monitor has a yellow warning
lamp in th e instrumen t cluste r for indicating
pressur e loss or a malfunction . Whether th e
warning lamp flashes or lights up indicates
whether a tire pressur e is to o low or th e tire
pressur e monitor is malfunctioning :R
if th e warning lamp is lit continuously, th e tire
pressur e on on e or mor e tires is significantly
to o low. The tire pressur e monitor is no t mal-
functioning . R
if th e warning lamp flashes for aroun d a
minute and then remain s lit constantly, th e
tire pressur e monitor is malfunctioning .354
Tire pressure
Wheels and tires

In addition to the warning lamp, a message
appears in the multifunction display. Observe
the information on display messages
( Y
page 268).
It may take up to ten minutes for a malfunction
of the tire pressure monitor to be indicated. A
malfunction will be indicated by the tire pres-
sure warning lamp flashing for approximately
one minute and then remaining lit. When the
malfunction has been rectified, the tire pressure
warning lamp goes out after a few minutes of
driving.
The tire pressure values indicated by the on-
board computer may differ from those meas-
ured at a gas station with a pressure gauge. The
tire pressures shown by the on-board 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.
The operation of the tire pressure monitor can
be affected by interference from radio transmit-
ting equipment (e.g. radio headphones, two-way
radios) that may be being operated in or near the
vehicle.
Checking the tire pressure electroni-
cally X
Make sure that the SmartKey is in position 2
in the ignition lock ( Y
page 138).X
Press the Y or e button on the steering
wheel to select the Serv. menu.X
Press the c or d button to select
Tire Pressure .X
Press the v button.
The current tire pressure of each tire is shown
in the multifunction display.
If the vehicle has been parked for longer than
20 minutes, the Tire pressure will be
displayed after driving a few minutes
message appears.
After a teach-in process, the tire pressure mon-
itor automatically detects new wheels or new
sensors. As long as a clear allocation of the tire
pressure value to the individual wheels is not
possible, the Tire Pressure Monitor Active
display message is shown instead of the tire
pressure display. The tire pressures are already
being monitored.
If an emergency spare wheel is mounted, the
system may continue to show the tire pressure of the wheel that has been removed for a few
minutes. If this occurs, note that the value dis-
played for the position where the spare wheel is
mounted is not the same as the current tire
pressure of the emergency spare wheel.
Tire pressure monitor warning mes-
sages If the tire pressure monitor detects a pressure
loss in one or more tires, a warning message is
shown in the multifunction display. The yellow
tire pressure warning lamp then lights up. R
If the Please Correct Tire Pressure
message appears in the multifunction display,
the tire pressure in at least one tire is too low.
The tire pressure must be corrected when the
opportunity arises. R
If the Check Tires message appears in the
multifunction display, the tire pressure in at
least one tire has dropped significantly. The
tires must be checked. R
If the Warning Tire Malfunction message
appears in the multifunction display, the tire
pressure in at least one tire has dropped sud-
denly. The tires must be checked.
Be sure to observe the instructions and safety
notes in the display messages in the "Tires" sec-
tion ( Y
page 268).
If the wheel positions on the vehicle are rotated,
the tire pressures may be displayed for the
wrong positions for a short time. This is rectified
after a few minutes of driving, and the tire pres-
sures are displayed for the correct positions.
Restarting the tire pressure monitor When you restart the tire pressure monitor, all
existing warning messages are deleted and the
warning lamps go out. The monitor uses the cur-
rently set tire pressures as the reference values
for monitoring. In most cases, the tire pressure
monitor will automatically detect the new refer-
ence values after you have changed the tire
pressure. However, you can also define refer-
ence values manually as described here. The tire
pressure monitor then monitors the new tire
pressure values. X
Set the tire pressure to the value recommen-
ded for the corresponding driving situation on
the Tire and Loading Information placard on
the driver's side B-pillar ( Y
page 349).Tire pressure 355
Wheels and tires Z