Chrysler 2005 Sebring, Service Manual, Page: 2594 / 3204

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in t egr a t ed h ydr a u lic con t r ol u n it (H CU), 1 pu m p
m ot or.
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4 wh eel speed sen sor /t on e wh eel a ssem blies
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ABS wa r n in g in dica t or
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fu ses a n d wir in g h a r n ess
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flu id r eser voir
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br a ke la m p swit ch
AB S With Tra c tio n Co n tro l
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ABM wit h Tr a ct ion Con t r ol pr ogr a m m in g
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H CU wit h fou r a ddit ion a l con t r ol va lves.
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TCS Swit ch
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TCS In dica t or
3.3.1 ABS AND BRAKE WARNING
INDICATORS
Th e a m ber ABS wa r n in g in dica t or is loca t ed in
t h e in st r u m en t clu st er. It is u sed t o in for m t h e
dr iver t h a t t h e a n t ilock fu n ct ion h a s been t u r n ed
off. Th e ABS wa r n in g in dica t or is con t r olled by t h e
ABM. Th e ABM con t r ols t h e la m p wit h a com m a n d
over t h e P CI bu s.
Th e ABS Wa r n in g In dica t or will r em a in lit du r in g
ever y key cycle u n t il a cir cu it or com pon en t fa u lt is
r epa ir ed a n d t h e ABM n o lon ger det ect s t h e fa u lt .
Aft er r epa ir of a sen sor sign a l fa u lt or a pu m p m ot or
fa u lt , t h e ABM m u st sen se a ll fou r wh eels a t 25
km /h (15 m ph ) befor e it will ext in gu ish t h e ABS a n d
TCS In dica t or.
Th e In st r u m en t Clu st er will illu m in a t e t h e ABS
Wa r n in g In dica t or if it loses com m u n ica t ion wit h
t h e ABM.
Th e r ed BRAKE wa r n in g in dica t or is a lso loca t ed
in t h e in st r u m en t clu st er. It ca n be a ct iva t ed in
sever a l wa ys. Applica t ion of t h e pa r kin g br a ke or a
low flu id sign a l fr om t h e flu id level swit ch loca t ed in
t h e m a st er cylin der r eser voir will ca u se t h e in dica -
t or t o com e on .
3.3.2 ANTI-LOCK BRAKE MODULE
Th e ABM is a m icr opr ocessor-ba sed device t h a t
m on it or s wh eel speeds a n d con t r ols t h e a n t ilock
fu n ct ion s. Th e ABM con t a in s t wo m icr opr ocessor s
t h a t r eceive iden t ica l sen sor sign a ls a n d t h en in de-
pen den t ly pr ocess t h e in for m a t ion . Th e r esu lt s a r e
t h en com pa r ed t o m a ke su r e t h a t t h ey a gr ee. Ot h -
er wise, t h e ABM will t u r n off t h e a n t ilock a n d t u r n
on t h e ABS a m ber wa r n in g in dica t or.
Th e pr im a r y fu n ct ion s of t h e ABM a r e t o:
• det ect wh eel lockin g t en den cies
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con t r ol flu id pr essu r e m odu la t ion t o t h e br a kes
du r in g a n t ilock st op
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m on it or t h e syst em for pr oper oper a t ion
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m a n a ge t r a ct ion con t r ol fu n ct ion s
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pr ovide com m u n ica t ion t o t h e DRBIII " wh ile in
dia gn ost ic m ode
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st or e dia gn ost ic in for m a t ion in n on -vola t ile m em -
or y
Th e ABM con t in u ou sly m on it or s t h e speed of
ea ch wh eel. Wh en a wh eel lockin g t en den cy is
det ect ed, t h e ABM will com m a n d t h e a ppr opr ia t e
va lve t o m odu la t e br a ke flu id pr essu r e in it s h y-
dr a u lic u n it . Br a ke peda l posit ion is m a in t a in ed
du r in g a n a n t ilock st op by bein g a closed syst em .
Th e ABM con t in u es t o con t r ol pr essu r e in in divid-
u a l h ydr a u lic cir cu it s u n t il a wh eel lockin g t en -
den cy is n o lon ger pr esen t . Th e ABM t u r n s on t h e
pu m p m ot or du r in g a n a n t ilock st op.
Th e a n t ilock br a ke syst em is con st a n t ly m on i-
t or ed by t h e ABM for pr oper oper a t ion . If t h e ABM
det ect s a syst em m a lfu n ct ion , it ca n disa ble t h e
a n t ilock syst em a n d t u r n on t h e ABS wa r n in g
in dica t or. If t h e a n t ilock fu n ct ion is disa bled, t h e
syst em will r ever t t o st a n da r d ba se br a ke syst em
oper a t ion .
Th e ABM in pu t s in clu de t h e followin g:
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dia gn ost ic com m u n ica t ion
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fou r wh eel speed sen sor s
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t h r ee power feeds: va lve, pu m p, a n d m icr opr oces-
sor
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br a ke la m p swit ch
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t r a ct ion con t r ol swit ch
Th e ABM ou t pu t s in clu de t h e followin g:
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ABS wa r n in g in dica t or a ct u a t ion
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12 volt s su pply t o wh eel speed sen sor s
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va lve a ct u a t ion
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dia gn ost ic com m u n ica t ion
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P CI bu s com m u n ica t ion
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t r a ct ion con t r ol la m p illu m in a t ion
3.3.3 HYDRAULIC CONTROL UNIT
Th e h ydr a u lic con t r ol u n it (H CU) con t a in s t h e
va lve block a ssem bly, a n d pu m p/m ot or a ssem bly.
Th e H CU is a t t a ch ed t o t h e ABM.
Va lv e B lo c k As s e m bly : Th e va lve block a ssem -
bly con t a in s va lves wit h fou r in let va lves a n d fou r
ou t let va lves. Th e in let va lves a r e spr in g-loa ded in
t h e open posit ion a n d t h e ou t let va lves a r e spr in g
loa ded in t h e closed posit ion . Du r in g a n a n t ilock
st op, t h ese va lves a r e cycled t o m a in t a in t h e pr oper
slip r a t io for ea ch wh eel. If a wh eel det ect s slip, t h e
in let va lve is closed t o pr even t a n d fu r t h er pr essu r e
in cr ea se. Th en t h e ou t let va lve is open ed t o r elea se
t h e pr essu r e t o t h e a ccu m u la t or s u n t il t h e wh eel is
n o lon ger slippin g. On ce t h e wh eel is n o lon ger
slippin g, t h e ou t let va lve is closed a n d t h e in let
va lve is open ed t o r ea pply pr essu r e. If t h e wh eel is
deceler a t in g
wit h in it s pr edet er m in ed lim it s
(pr oper slip r a t io), t h e in let va lve will close t o h old
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GEN ERAL I N FORM AT I ON