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Fig. 192 Battery window on the top of the 12-volt vehicle battery (illustration).
First read and observe the introductoryinformation and safety warnings
The electrolyte level of the 12-volt vehicle battery should be checked regularly in high-mileage
vehicles, in hot countries and in older 12-volt vehicle batteries. The 12-volt vehicle battery is
otherwise maintenance-free.
Vehicles with an auxiliary heater Auxiliary heater and ventilationare fitted with special vehicle
batteries. The electrolyte level of these 12-volt vehicle batteries cannot be checked for technical
reasons. Go to a qualified workshop to have the 12-volt vehicle battery checked.
Preparations
eparing the vehicle for working in the engine compartment In the engine compartment
In the engine compartment
Checking the electrolyte level (12-volt vehicle batteries with battery window)
e for you to clearly see the colour indicator in the round
battery window on the top of the 12-volt vehicle battery Fig. 192(arrow). Never use naked
flames or glowing objects as a light source.
s according to the electrolyte level in the
12-volt vehicle battery.
Light yellow or without colourThe electrolyte level of the 12-volt vehicle battery is too low. The 12-
volt vehicle battery should be checked and replaced by a qualified workshop if necessary.BlackThe
electrolyte level of the 12-volt vehicle battery is correct.
WARNING
Any work on the 12-volt vehicle battery can cause serious chemical burns, explosions and electric
shocks.
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-volt vehicle battery
-volt vehicle
battery.
e cable and then the negative cable
Various indicator lamps may light up after the 12-volt vehicle battery has been connected and the
ignition is switched on. They will go out when you drive a short distance at a speed of approximately
15 20 km/h (10 12 mph). If the indicator lamps remain lit up, the vehicle should be checked by a
qualified workshop.
If the 12-volt vehicle battery was disconnected for an extended period, the system may not able to
calculate or correctly display the time when the next service is due Instrument cluster
the maximum permissible service intervals Service
Automatic switch-off for electrical consumers
The intelligent vehicle electrical system management function automatically implements a range of
measures to prevent the 12-volt vehicle battery from discharging under high loads:
power supply to the 12-volt socket and the cigarette lighter may be interrupted temporarily
while the engine is being started.
The vehicle electrics management system cannot always prevent the 12-volt vehicle battery from
being discharged, for example if the ignition is left on over a long period with the engine off or the
side lights or parking lights are left on over a long period of time.
12-volt vehicle battery is discharged
gnition is switched on.
Auxiliary heater and ventilation
WARNING
Incorrectly mounting the battery and using incorrect 12-volt vehicle batteries can cause short
circuits, fire and serious injuries.
-free and leak-proof 12-volt vehicle batteries that have the same
properties, specifications and dimensions as the factory-fitted 12-volt vehicle battery.
WARNING
A highly explosive mixture of gases is given off when the 12-volt vehicle battery is being charged.
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ator. The 12-volt vehicle battery will not be charged by the alternator while the
vehicle is in motion.
Switch off any electrical consumers that are not required. Inform a qualified workshop. Have the
electrical system checked.
The start/stop system cannot start the engine Start/stop system
and vehicle battery (12-volt)
The central warning lamp lights up yellow and the text message 12 V battery low. Charge by driving.
is displayed.
The charge level of the vehicle battery is insufficient.
Recharge the 12-volt vehicle battery by driving the vehicle for an extended time.
The start/stop system cannot start the engine Start/stop system
and vehicle battery (12-volt)
The central warning lamp lights up red and the text message Replace 12 V battery. Workshop. is
displayed.
The vehicle battery condition is not ok.
Seek expert assistance and have the battery checked and replaced if necessary.
The start/stop system cannot start the engine Start/stop system
Wheels and tyres
Tyre monitoring system
Introduction
This chapter contains information on the followingsubjects:
Tyre Pressure Loss Indicator
Troub
The tyre monitoring system warns the driver when the tyre pressures are too low.
The tyre monitoring system monitors various parameters (for example, rolling circumference) of all
wheels using ABS sensors (indirect measurement).
WARNING
The intelligent tyre monitoring system technology cannot overcome the laws of physics, and
functions only within the limits of the system. Incorrect handling of the wheels and tyres can lead to
a sudden loss of pressure in the tyres, tread separation and even tyre blow-out.
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