rea d opposit e swit ch sta t es. Note: The BS and
BLS are in the same switch housing.
BRAKE LAMP SWITCH (BLS): Th is switch pr e-
pa res t h e CAB for a possible an tilock even t . Th e
CAB u ses a n ou t pu t st a t e volt age fr om t he BLS
wh en t he br a ke peda l is eit her depr essed/r elea sed.
Th e F u sed Ignit ion Swit ch Out pu t cir cu it su pplies
12 volt s t o t h e BLS. A depressed bra k e peda l will
close th e BLS circu it a n d t h e BLS Out pu t cir cu it
su pplies 12 volt s a t t h e CAB. Wh en t h e dr iver
relea ses t h e br ake peda l, t he BLS Ou t pu t cir cu it
volt age dr ops t o 0 volt s a n d t he CAB sen ses t h e
br a k e peda l st a t e. Th is t ells t h e CAB wha t posit ion
th e br a ke peda l is cu r ren t ly in t o m a ke an ABS
even t possible. Wh en u sin g th e DRBIII" in I np uts /
Ou t pu ts, th e BS a nd BLS will r ea d opposit e swit ch
stat es. Note: The BS and BLS are in the same
switch housing.
TRACTION CON TROL S YS TE M S WITCH
(TCS S ): Th is swit ch sign a ls t h e CAB to eith er tur n
ON or OF F th e TCS. Th e dr iver ca n t oggle t he
TCSS, which r eceives 12 volt s from t h e D (+) Rela y
Ou t pu t circu it . Depen din g on t he posit ion of t he
TCSS, open or closed, t h e CAB receives t h e TCSS
st at e volt a ge on t he TCS Swit ch Sen se circu it .
Wh en 12 volt s a r e applied t o th e TCS Switch Sen se
cir cu it , the TCS is OF F. Wh en n o volt a ge is pr esent ,
the TCS is ON.
WHE E L S P EE D S E N S OR S AN D TON E
WHE E LS : Th e Bosch 5.7 syst em u ses on e pa ssive
WSS on ea ch wh eel. Th e sen sor mea su r es t h e wh eel
speed by m on it or in g a r ot at in g ton e wh eel. As th e
teet h of th e t on e wh eel m ove th r ou gh t h e ma gn et ic
field of t he sen sor a n AC volt a ge an d a m per age is
gen er a t ed. Th is sign al fr equ en cy in cr ea ses or de-
crea ses pr opor tion ally t o th e speed of t h e wh eel.
Th e CAB m on it or s t h is sign a l t o check for a su dden
cha n ge in sin gle or m u lt iple wh eel deceler a tion s. If
th e deceler a t ion of one or m ore wh eels is n ot wit hin
a pr edet er m in ed amou n t, t h e CAB t a kes contr ol for
an t ilock a ction t h r ough t h e H CU. Ea ch WSS h a s a
ma gn et ic in du ct ive pick u p coil (WSS) th a t is
mou n ted to a fixed com pon en t. Th er e is an a ir ga p
bet ween t he t on e wh eel a n d th e speed sensor a s-
sembly. Dia gn ost ica lly, th e coils of t he Wh eel Speed
Sensor s ha ve t h e sa m e a m ou nt of r esist an ce. Wh en
mea su red acr oss th e CAB har n ess con n ect or t er m i-
na ls, th e r esist a nce sh ou ld be bet ween 1100 - 1800
ohm s. Refer t o ser vice ma n ua l for WSS r epla cem ent
an d a ir ga p specifica t ion s.
Cor r ect ABS oper at ion is depen den t on Ton e
Wh eel speed sign a l fr om th e WSS. Th e veh icle
wh eels and tir es sh ou ld all be t h e sa m e size an d
type t o get accu r a te signa ls. In a ddit ion , a ll t ir es
sh ould be at r ecom men ded t ir e pr essu res.
3.7. 5 S EL F T ES T S
Th e syst em soft wa r e in clu des sever a l self t est s
th a t a re perfor m ed every tim e t h e ign it ion is tu r n ed
on a n d t h e veh icle is dr iven . Som e of t h e self test s
occur im media tely, while oth er s occu r un der nor ma l
dr ivin g condit ion s wh ile n ot in a nt ilock opera t ion .
Th e CAB checks cont in uou sly for a m issin g or
er r a tic WSS sign a ls/cir cuit s, ton e wh eels, solen oids,
pu mp mot or or solen oid r ela y by per form ing sever a l
test s su ch a s: dyn a m ic, st at ic, ohm ic, volt a ge dr op,
an d tim ed r espon se. If a ny com pon en t exh ibit s a
fau lt du r in g t est in g, th e CAB will requ est to illu mi-
na t e t he ABS a n d TCS wa r n in g in dica tor s.
As an addit ion al ch eck of t he E SP syst em , a roa d
test pr ocedu re is a va ila ble on t h e DRBIII".This
test sh ould be car r ied ou t wh en a n y E SP com pon en t
is r eplaced in or der t o ensu r e pr oper fun ct ion . Sin ce
th e wh eel speed sen sor s a re requ ir ed in pu t s to th e
ESP, this test sh ou ld also be per for med if t he wh eel
speed sensor s a r e r epla ced.
Fir st , t h e br a kes a re a pplied wit h t he veh icle
st at ion a r y. Th en , t he veh icle is dr iven a t a ppr oxi-
ma t ely 6 MP H . Th e dr iver h as to m ake left a n d
right turns, with a minimum 90 degree steering
tu r nin g a ngle. If t he in dica tor la mp goes out , ever y-
th in g is in or der. If t h e la m p r em ain s illu min at ed,
the DRBIII" will displa y t h e fault codes th a t a re
cau sing t he t est to fail. Th e r oad t est fu n ction is set
in t h e ESP con t rol modu le, an d can on ly be dea cti-
va t ed once th ere ar e n o m or e fa u lt codes det ect ed.
Th e St eer in g Angle Sen sor mu st be in it ia lized. A
pr ocedur e is car r ied ou t usin g t h e DRBIII" to
en su r e t h at t h e m odu le det ects t h e exa ct posit ion of
th e sen sor. Th e sen sor m u st be ca libr at ed an y t im e
wh eel a lign m en t is cha n ged, th e st eer ing colu m n is
rem oved a n d re-in st alled, or th e sen sor is r epla ced.
3.8 USING THE DRBIII!
Refer t o t h e DRBIII" u ser ’s gu ide for in st ru ct ion s
an d a ssist an ce wit h r ea din g dia gn ost ic t r ou ble
codes, er asin g dia gn ost ic t r ouble codes a n d ot h er
DRBII I" fun ct ion s.
3.9 DRBIII! ERROR MESSAGES
Un der nor m al oper at ion , t h e DRBIII" will dis-
pla y on e of only t wo er ror m essa ges:
— User -Request ed WARM Boot or U ser-Requ est ed
COLD Boot .
If the DRBIII" sh ould displa y a ny ot her er ror
messa ge, r ecor d t h e en tir e display a nd ca ll t he
STAR Cent er for in for m at ion a n d a ssist an ce. Th is
is a sa m ple of su ch an er r or m essa ge displa y:
4
GEN ERAL I N FORM AT I ON
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