2018 AUDI S4 wiring

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Trailer towing Driving with a trailer
General information
Your Audi was designed primarily for passenger
transportation .
If you plan to tow a trailer, please remember that
the additional load will affect durability, econo­ my and performance.
Trailer towing not only places more stress on the
vehicle, it also calls for more concentration from
the driver.
For this reason, always follow the operating and
driving instructions provided and use common
sense.
Technical requirements
Trailer hitch
Use a weight-carrying hitch conforming to the
gross trailer weight. The hitch must be suitable
for your vehicle and trailer and must be mounted
securely on the vehicle's chassis at a technically
sound
location . Use only a trailer hitch with a re­
movable ball mount . Always check with the trail­
er hitch manufacturer to make sure that you are
using the correct hitch.
Do not use a bumper hitch.
The hitch must be installed in such a way that it
does not interfere with the impact -absorbing
bumper system. No modifications should be
made to the vehicle exhaust and brake systems .
From time to time, check that all hitch mounting
bo lts remain securely fastened.
When you are not towing a trailer,
remove the
tra iler hitch ball mount . This prevents the hitch
from causing damage shou ld your vehicle be
struck from beh ind ¢
,&. .
Trailer brakes
If your trailer is equipped with a braking system,
check to be sure that it conforms to all regula­
tions .
Trailer towing
The trailer hydraulic brake system must not be
directly connected to the vehicle's hydraulic
brake
system ¢.&. .
Safety chains
Always use safety chains between your vehicle
and the trailer.
Trailer lights
T ra iler lights must meet all regulations . Be sure
to check w ith your author ized Audi dealer for cor­
rect wiring, switches and relays.
Mirrors
If you are unable to see the traffic behind you us­
ing the regular outside mirrors, then you
must in­
stall extended mirrors. It is important that you
always have clear vision to the rear.
,8. WARNING
After removing the traile r hitch, do not store
it in your vehicle. In case of sudden braking,
the hitch could fly forward and injure you or
your passengers.
Operating instructions
Maximum trailer weight
A trailer for your vehicle is limited to a typical
class 1 or class 2 trailer.
Trailer load distribution
Be sure the load in the trailer is held securely in
place to prevent it from shifting forward, back­
ward or sideways.
Never allow a passenger to ride in a trailer ¢.&.
in Driver messages on page 100 .
Engine cooling system
Towing a trailer makes the engine work harder. It
is important that the cooling system's perform ­
ance is up to the additional load. Make sure that
the cooling system has enough fluid.
Tire pressure
When towing a trailer, inflate the tires of your
vehicle to the tire pressure listed under "Full
load" on the label ¢ page 344. Inflate trailer
99

Monitoring the
Advanced Airbag System
Airbag monitoring indicator light
Two separate indicators monitor the fun ction of
the A dvanced Airbag System : the
El ligh t and
t he
PASSENGER AIR BAG OFF ~ ; ON @ Light.
The Advanced Airbag System as we ll as the side
a ir bags and side c urta in air bags with ejec tion
m it iga tion fea tures ( in cludi ng the e lectro nic con­
tro l uni t, sensors and sys tem wiring) are a ll
monitored co nti nu ously to ma ke sure that they
are funct ioning properly whenever the ignition is
on. Every t ime you turn on the ignition, the air ­
bag system ind icator
light E,lwill come on for a
few seconds (function check).
The system must be inspected when the
indicato r light
E,I:
- does not come on when the ignit ion is switched
on
- does not go out a few seconds after you have
switched on the ign ition, o r
- comes on w hile driving
If an airbag sys tem malf unct ion is de te cted, the
indicator light w ill come on to serve as a co nstant
remi nder to have the system inspected immedi­
ately .
If a mal function occurs that turns the front air­
bag on the passenger side off, the
PASSENGER
AIR BAG
OFF ~. lig ht w ill come o n an d stay on
whenever the ignit ion is on.
A WARNING
An airbag system that is not funct io ning prop­
erly cannot provide supplemental p rotection
in a frontal crash .
- If the airbag indicato r
light¢ page 32
comes whe n the vehicle is be ing used, have
th e sys te m in spect ed immed iate ly by yo ur
au tho riz ed Aud i deale r.
It is possible that
th e air bag will i nflate w hen it i s n ot su p­
p osed to, o r will not i nfla te whe n it shou ld.
Airbag system
PASSENGER AIR BAG OFF '1; ON @ light
Fi g. 241 Sect io n fro m th e headli ner: PASSENGE R AIR BAG
OFF~ ; ON @ lig ht
T he PASSENGER AIR BAG OFF ~; ON@ light is
located in t he
headliner ¢ fig. 241.
The PASSENGER AIR BAG OFF ~; light will come
o n and stay on to tell you w hen t he fro nt Ad­
van ced Air bag o n the p assenge r side has been
tu rned
off by t he e lec tron ic control unit . If the
bulb fo r the
PASSENGER AIR BAG OFF ~; ON@
light b urns o ut, t he a irbag ind icator light El w ill
come on to signal a ma lfunction in the Advanced
Airbag System. Altho ugh the burned-out b ulb
will not change the way the front passenger's
frontal a irbag works , it w ill no longer be possible
to use the
PASSENGER AIR BAG OFF ~; ON@
ligh t to make s ure that the airbag on/off s tatus is
c or rec t fo r th e o ccu pan t on the front passenge r
sea t. Have the airb ag system inspec ted immedi­
ate ly by yo ur au thorized A udi d ealer .
The PASSENGER AIR BAG OFF~; ON@ light
will blink for about S seconds when:
- the capacit ive passenger detection system,
which switc hes the front sea t passe nger's fron ­
tal Advanced Airbag o n and off, detects a
change in the st atus of the front pa sse nger
se at.
As soon as the
PASSENGER AIR BAG OFF ~; ON
@ light s tops blin kin g, a lways make sure that the
air bag st atus (on o r off) as shown by the ligh t is
prope r for the age, size and e lec trica l capacitance
of t he perso n occ up ying the front passenger
seat . Always ma ke sure that the safety be lt fo r
t h e front passenger seat is proper ly fastened .
The PASSENGER AIR BAG OFF~;/ PASSENGER
AIR BAG ON
@ light will show the statu s of the ..,.
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