341
If and when
Starting assistance
Introduction
If the engine fails to start because of a discharged battery, the battery of an-
other vehicle can be used to start the engine. Before starting, check the
magic eye on the battery ⇒ page 292.
For starting assistance, jump lead cables conforming to the standard
DIN 72553 are required (see the cable manufacturer instructions). The jump
lead cable must be at least 25 mm 2
in section (0.038 inches 2
) for petrol en-
gines, and 35 mm 2
(0.054 inches 2
) for diesel engines.
For vehicles whose battery is not in the engine compartment, the jump
leads should only be connected to the starting assistance connection
points in the engine compartment.
Additional information and warnings:
● Starter assist systems (Start-Stop function) ⇒ page 196
● Working in the engine compartment ⇒ page 279
● Selective Catalytic Reduction (AdBlue) ⇒ page 275
● Vehicle battery ⇒ page 292
WARNING
Incorrect use of jump leads and incorrectly jump starting could cause the
battery to explode resulting in serious injury. Please observe the follow-
ing rules to minimise the risk of a battery explosion:
● All work involving the vehicle battery and electrical system can cause
corrosion, fire and serious electric shocks. Always read and take into ac-
count the safety warnings and standards before beginning work on the
battery ⇒ page 292, Vehicle battery.
WARNING (Continued)
● The battery providing current must have the same voltage (12V) and
approximately the same capacity (see markings on battery) as the flat
battery.
● Never charge a frozen or recently thawed battery. A flat battery can al-
so freeze at temperatures close to 0 °C (+32 °F).
● If a battery is frozen and/or has been frozen then it must be replaced.
● A highly explosive mixture of gases is released when the battery is
being charged. Always keep lit cigarettes, open flames, sparks and fire
far from the battery. Never use a mobile telephone when connecting and
removing the jump leads.
● Charge the battery only in well ventilated areas given that when the
battery is charged by outside assistance, it creates a mix of highly explo-
sive gases.
● Jump leads should never enter into contact with moving parts in the
engine compartment.
● Never switch the positive and negative poles or connect the jump
leads incorrectly.
● Note the instructions provided by the manufacturer of the jump leads.
CAUTION
To avoid considerable damage to the vehicle electrical system, note the fol-
lowing carefully:
● If the jump leads are incorrectly connected, this could result in a short
circuit.
● The vehicles must not touch each other, otherwise electricity could flow
as soon as the positive terminals are connected.
Safety FirstOperating instructionsPractical tipsTechnical Specifications
343
If and when
The vehicles should not touch. Otherwise, current may be allowed to flow
when the positive poles are connected.
Connect the clamps so they have good metal-to-metal contact with the ter-
minals.
If the engine fails to start straight-away, switch off the starter after about 10
seconds and try again after about a minute.
Complete operations only in the sequence given.
Jump lead terminal connections
● Switch off the ignition of both vehicles ⇒ page 172.
● Likewise, open the battery cover in the engine compartment
⇒ page 292, or remove the positive pole cap from one side 1)
, in the direc-
tion of the arrow ⇒ fig. 217.
● Connect one end of the red jump lead to the positive terminal
⇒ fig. 218 +
or ⇒
fig. 217 + of the vehicle with the flat battery A ⇒ .
● Connect the other end of the red jump lead to the positive terminal + in
the vehicle providing assistance B.
● For vehicles without Start-Stop system: Connect one end of the black
jump lead to the negative terminal -
in the vehicle providing assistance
B ⇒ fig. 218.
● For vehicles with Start-Stop system: Connect one end of the black X
jump lead to a suitable ground connection, a solid piece of metal in the en-
gine block, or to the engine block
⇒ fig. 219.
● Connect the other end of the black jump lead X
to a solid metal compo-
nent connected to the engine block, or onto the engine block itself of the
vehicle with the flat battery however, connect it as far away as possible from
the battery A
⇒ .
● Place the leads so that they cannot be caught by any moving parts in the
engine compartment. Switching on
●
Start the engine of the vehicle supplying current and let it run at idling
speed.
● Start the engine of the car with the flat battery and wait two or three mi-
nutes until the engine is “running smoothly”.
Removing the jump leads
● Before you remove the jump leads, switch off the headlights (if they are
switched on).
● Turn on the heating and rear window heater in the vehicle with the flat
battery. This helps minimise voltage peaks which are generated when the
leads are disconnected.
● With the engines running, disconnect the leads in reverse order to con-
nection.
● Close the battery cover, or replace the positive pole cap 1)
.
WARNING
Incorrectly jump starting could cause the battery to explode resulting in
serious injury. Please observe the following rules to minimise the risk of
a battery explosion:
● All work involving the vehicle battery and electrical system can cause
corrosion, fire and serious electric shocks. Always read and take into ac-
count the safety warnings and standards before beginning work on the
battery ⇒ page 292, Vehicle battery.
● Always protect your eyes with suitable working goggles and never
lean over the vehicle battery.
● The jump leads must be connected in the correct order: first the posi-
tive cable, then the negative cable.
1)
Vehicles whose battery is not located in the engine compartment ⇒ page 342.
Safety FirstOperating instructionsPractical tipsTechnical Specifications
