Jeep Cherokee 1999 Electronic Service Manual page 306

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DESCRIPTION AND OPERA TION
BATTERY TEMPERATURE SENSOR . . . . . . . . . . 2
CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . . . 1
ELECTRONIC VOLTAGE REGULATOR . . . . . . . . . 2
GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DIAGNOSIS AND TESTING
BATTERY TEMPERATURE SENSOR . . . . . . . . . . 3
CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . . . 2
DESCRI PT I ON AN D OPERAT I ON
CHARGING SYSTEM
DESCRIPTION
Th e ch a r gin g syst em con sist s of:
• Gen er a t or
• E lect r on ic Volt a ge Regu la t or (E VR) cir cu it r y
wit h in t h e P ower t r a in Con t r ol Modu le (P CM)
• Ign it ion swit ch (r efer t o Gr ou p 8D, Ign it ion Sys-
t em for in for m a t ion )
• Ba t t er y (r efer t o Gr ou p 8A, Ba t t er y for in for m a -
t ion )
• Ba t t er y t em per a t u r e sen sor
• Gen er a t or La m p (if equ ipped)
• Ch eck Ga u ges La m p (if equ ipped)
• Volt m et er (r efer t o Gr ou p 8E , In st r u m en t P a n el
a n d Ga u ges for in for m a t ion )
• Wir in g h a r n ess a n d con n ect ion s (r efer t o Gr ou p
8W, Wir in g for in for m a t ion )
OPERA TION
Th e ch a r gin g syst em is t u r n ed on a n d off wit h t h e
ign it ion swit ch . Th e syst em is on wh en t h e en gin e is
r u n n in g a n d t h e ASD r ela y is en er gized. Wh en t h e
ASD r ela y is on , volt a ge is su pplied t o t h e ASD r ela y
sen se cir cu it a t t h e P CM. Th is volt a ge is con n ect ed
t h r ou gh t h e P CM a n d su pplied t o on e of t h e gen er a -
t or field t er m in a ls (Gen . Sou r ce +) a t t h e ba ck of t h e
gen er a t or.
Th e a m ou n t of DC cu r r en t pr odu ced by t h e gen er-
a t or is con t r olled by t h e E VR (field con t r ol) cir cu it r y
con t a in ed wit h in t h e P CM. Th is cir cu it r y is con -
n ect ed in ser ies wit h t h e secon d r ot or field t er m in a l
a n d gr ou n d.
A ba t t er y t em per a t u r e sen sor, loca t ed in t h e ba t -
t er y t r a y h ou sin g, is u sed t o sen se ba t t er y t em per a -
t u r e. Th is t em per a t u r e da t a , a lon g wit h da t a fr om
CHARGING SYSTEM
CON T EN T S
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ON-BOARD DIAGNOSTIC TEST FOR
CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . 3
REMOVAL AND INSTALLA TION
BATTERY TEMPERATURE SENSOR . . . . . . . . . . 4
GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
SPECIFICA TIONS
GENERATOR RATINGS . . . . . . . . . . . . . . . . . . . . 5
TORQUE CHART . . . . . . . . . . . . . . . . . . . . . . . . . 5
m on it or ed lin e volt a ge, is u sed by t h e P CM t o va r y
t h e ba t t er y ch a r gin g r a t e. Th is is don e by cyclin g t h e
gr ou n d pa t h t o con t r ol t h e st r en gt h of t h e r ot or m a g-
n et ic field. Th e P CM t h en com pen sa t es a n d r egu la t es
gen er a t or cu r r en t ou t pu t a ccor din gly.
All veh icles a r e equ ipped wit h On -Boa r d Dia gn os-
t ics (OBD). All OBD-sen sed syst em s, in clu din g E VR
(field con t r ol) cir cu it r y, a r e m on it or ed by t h e P CM.
E a ch m on it or ed cir cu it is a ssign ed a Dia gn ost ic Tr ou -
ble Code (DTC). Th e P CM will st or e a DTC in elec-
t r on ic m em or y for cer t a in fa ilu r es it det ect s. Refer t o
On -Boa r d Dia gn ost ics in Gr ou p 25, E m ission Con t r ol
Syst em for m or e DTC in for m a t ion .
Th e Ch eck Ga u ges La m p (if equ ipped) m on it or s:
c h a rg in g s y s te m v o lta g e , en gin e coola n t t em per a -
t u r e a n d en gin e oil pr essu r e. If a n ext r em e con dit ion
is in dica t ed, t h e la m p will be illu m in a t ed. Th is is
don e a s r em in der t o ch eck t h e t h r ee ga u ges. Th e sig-
n a l t o a ct iva t e t h e la m p is sen t via t h e CCD bu s cir-
cu it s. Th e la m p is loca t ed on t h e in st r u m en t pa n el.
Refer t o Gr ou p 8E , In st r u m en t P a n el a n d Ga u ges for
a ddit ion a l in for m a t ion .
GENERA TOR
DESCRIPTION
Th e gen er a t or is belt -dr iven by t h e en gin e u sin g a
ser pen t in e t ype dr ive belt . It is ser viced on ly a s a
com plet e a ssem bly. If t h e gen er a t or fa ils for a n y r ea -
son , t h e en t ir e a ssem bly m u st be r epla ced.
OPERA TION
As t h e en er gized r ot or begin s t o r ot a t e wit h in t h e
gen er a t or, t h e spin n in g m a gn et ic field in du ces a cu r-
r en t in t o t h e win din gs of t h e st a t or coil. On ce t h e
gen er a t or begin s pr odu cin g su fficien t cu r r en t , it a lso
pr ovides t h e cu r r en t n eeded t o en er gize t h e r ot or.
CHARGING SYSTEM 8C - 1
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