Audi Q7 361 - Airbag Control Unit Functionality

P a ssenger pr otection
Airbag contro l unit J234
T h e purpose of the electronics integr a t ed in the airbag contr o l unit is t o detec t vehicl e decel e r a tion or
a ccel e r a tion and t o e v al ua te it so a s t o detect a vehic l e impact. In order t o dete ct ve h i cl e decel e r a tion or
a ccel e r a tion during a n imp a ct, e x tern al sensors a r e use d in addition t o the sensor s instal led inside the contr o l
unit. T h e electronics in the contr o l un it detect a cr a s h ba se d a l one on the in f o rmation r e ceived fr om the sen s ors.
O nly once all the sensor inf o rmation ha s b e en e v alu a ted by the co ntr o l u n it elec tr onics c a n the electronics
decide wh e n and which saf e ty compo n ents shou ld be activated.
T h e ai r b ag co ntr o l u n i t i s abl e t o detec t fr o n tal , side a nd r e ar i m pac t s.
A fur t her ta sk of the airbag contr o l unit is t o activate the r e levant r e str a int sys t ems ( b e l t tension e rs or belt
ten s io ner s and ai r b ag) depen d in g o n the t y pe a nd se veri ty of the impact a s well a s signalling the cr a s h t o
other vehicle systems.
T h e airbag electronics have the f o llowing main
ta sks:
– C ra s h d e t e ct i o n ( f ro n t , s i d e , re a r )
– D ef in ed trig gering of the belt tensione rs, airbags
and battery isolation igniter
– D ef in ed trig ge ring of the second fr ont a i rbag
stage
– E va lua t io n of al l i np u t i n f o rm a t ion
– P erma nent mon i t o ring of the comp l e te airbag
system
– I ndepende nt power supply via a c a pacit o r f o r
a def i ned time (appr o x . 150 ms)
– F au lt di spla y vi a a f a i l ur e war n i ng l a mp
– S t o r a g e of f a ult and cr a s h i n f orma t ion
– C ommunic a tion o f a cr a s h t o the other system
components via the drive CAN or discr e te cr a s h
output (conventional w i ring)
– A ctiva t ion o f sea t bel t wa rning system
361 _ 007
F o r inf orma t io n on which components must be r e pla c ed f o ll ow in g an a cc i de n t , pl ea se r e f e r to the app l ic a b le
W
o r k sho p Man u a l i n E L SA . An ai r b ag co ntr o l u n it c a n o nly be r e pl aced wi th the ai d o f an on li ne- c apabl e V A S
5051
or V A S 5052 . T h e guided f a ult-f i nding or gui d ed functi on appli c ati o ns must be u s ed f o r th is pur p ose. T h e
airbag contr o l unit must be c oded and adapted t o th e r e levant vehic l e. I f cod i ng or adaption is not per f ormed
cor r ectly , this ma y r e sul t in mal f unctions in oth e r vehicle syste m s, e.g. the ES P .
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