If and when371
Safety FirstOperating instructionsPractical tipsTe c h n i c a l D a t a
Starting assistance
Introduction
If the engine fails to start because of a discharged battery, the battery of
another vehicle can be used to start the engine. Before starting, check the
magic eye on the battery Ÿpage 318.
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 inches2) for petrol engines,
and 35 mm2 (0.054 inches2) 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:
xStarter assist systems (Start-Stop function) Ÿpage 221
xWorking in the engine compartment Ÿpage 304
xSelective Catalytic Reduction (AdBlue) Ÿpage 300
xVehicle battery Ÿpage 318
WARNING
Incorrect use of jump leads and 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:
xAll work involving the vehicle battery and electrical system can cause
corrosion, fire and serious electric shocks. Always read and take into
account the safety warnings and standards before beginning work on the
battery Ÿpage 318, “Vehicle battery”.
xThe battery providing current must have the same voltage (12V) and
approximately the same capacity (see markings on battery) as the flat
battery.
xNever charge a frozen or recently thawed battery. A flat battery can
freeze at temperatures around 0°C (+32 °F).
xIf a battery is frozen and/or has been frozen then it must be replaced.
xA 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.
xCharge 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.
xJump leads should never enter into contact with moving parts in the
engine compartment.
xNever switch the positive and negative poles or connect the jump leads
incorrectly.
xNote the instructions provided by the manufacturer of the jump leads.
Caution
To avoid considerable damage to the vehicle electrical system, note the
following carefully:
xIf the jump leads are incorrectly connected, this could result in a short
circuit.
xThe vehicles must not touch each other, otherwise electricity could flow as
soon as the positive terminals are connected.
WARNING (continued)
If and when373
Safety FirstOperating instructionsPractical tipsTe c h n i c a l D a t a 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 termi-
nals.
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
xSwitch off the ignition of both vehicles Ÿpage 195.
xLikewise, open the battery cover in the engine compartment Ÿpage 318,
or remove the positive pole cap from one side 3), in the direction of the arrow
Ÿpage 372, fig. 225.
xConnect one end of the red jump lead to the positive terminal
Ÿpage 372, fig. 226 or Ÿpage 372, fig. 225 of the vehicle with the
flat battery Ÿ.
xConnect the other end of the red jump lead to the positive terminal in
the vehicle providing assistance .
xFor vehicles without Start-Stop system: Connect one end of the black
jump lead to the negative terminal in the vehicle providing assistance
Ÿpage 372, fig. 226.
xFor vehicles with Start-Stop system: Connect one end of the black
jump lead to a suitable ground connection, a solid piece of metal in the
engine block, or to the engine block Ÿpage 372, fig. 227.
xConnect the other end of the black jump lead 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 Ÿ.
xPlace the leads so that they cannot be caught by any moving parts in the
engine compartment.Switching on
xStart the engine of the vehicle supplying current and let it run at idling
speed.
xStart the engine of the car with the flat battery and wait two or three
minutes until the engine is “running smoothly”.
Removing the jump leads
xBefore you remove the jump leads, switch off the headlights (if they are
switched on).
xTurn 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.
xWith the engines running, disconnect the leads in reverse order to
connection.
xClose the battery cover, or replace the positive pole cap 3).
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:
xAll work involving the vehicle battery and electrical system can cause
corrosion, fire and serious electric shocks. Always read and take into
account the safety warnings and standards before beginning work on the
battery Ÿpage 318, “Vehicle battery”.
xAlways protect your eyes with suitable working goggles and never lean
over the vehicle battery.
xThe jump leads must be connected in the correct order: first the positive
cable, then the negative cable.
xDo not attach the negative cable to parts of the fuel system or to the
brake hose/pipe.
3)Vehicles whose battery is not located in the engine compartment Ÿpage 372.
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