337
If and when
Starting assistance
Introduction If the engine fails to start because of a discharged battery, the battery of an-
other v
ehic
le can be used to start the engine. Before starting, check the
magic eye on the battery ⇒ page 288.
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) ⇒ pag
e 194
● Working in the engine compartment ⇒ pag
e 275
● Selective Catalytic Reduction (AdBlue) ⇒ pag
e 271
● Vehicle battery ⇒ pag
e 288 WARNING
Incorrect use of jump leads and incorrectly jump starting could cause the
batt er
y 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
corro
sion, fire and serious electric shocks. Always read and take into ac-
count the safety warnings and standards before beginning work on the
battery ⇒ page 288, Vehicle battery. WARNING (Continued)
● The b attery providing current must have the same voltage (12V) and
ap pr
oximately the same capacity (see markings on battery) as the flat
battery.
● Never charge a frozen or recently thawed battery. A flat battery can
freeze at
temperatures around 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 ch
arged. 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
batter
y 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 comp
artment.
● Never switch the positive and negative poles or connect the jump
lea
ds 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-
low in
g carefully:
● If the jump leads are incorrectly connected, this could result in a short
circ
uit.
● The vehicles must not touch each other, otherwise electricity could flow
as soon a
s the positive terminals are connected. Safety First Operating instructions Practical tips Technical Data
339
If and when
The vehicles should not touch. Otherwise, current may be allowed to flow
when the pos itiv
e 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 170.
● Lik
ewise, open the battery cover in the engine compartment
⇒ pag
e 288, or remove the positive pole cap from one side 1)
, in the direc-
tion of the arrow ⇒ fig. 215.
● Connect one end of the red
jump lead to the positive terminal
⇒ fig. 216 + or ⇒
fig. 215 + of the vehicle with the flat battery
A ⇒ .
● Connect the other end of the red
jump lead to the positive terminal + in
the v ehic
le 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. 216.
● For vehicles with St
art-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 bloc
k, or t
o the engine block ⇒ fig. 217.
● Connect the other end of the black
jump lead X to a solid metal compo-
nent c onnect
ed 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 c omp
artment. Switching on
●
Start the engine of the vehicle supplying current and let it run at idling
speed.
● Star
t 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
switc
hed on).
● Turn on the heating and rear window heater in the vehicle with the flat
batter
y. 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 injur
y. Please observe the following rules to minimise the risk of
a battery explosion:
● All work involving the vehicle battery and electrical system can cause
corro
sion, fire and serious electric shocks. Always read and take into ac-
count the safety warnings and standards before beginning work on the
battery ⇒ page 288, Vehicle battery.
● Always protect your eyes with suitable working goggles and never
lean o
ver the vehicle battery.
● The jump leads must be connected in the correct order: first the posi-
tive cab
le, then the negative cable. 1)
Vehicles whose battery is not located in the engine compartment ⇒ page 338. Safety First Operating instructions Practical tips Technical Data
