Jeep Cherokee 1999 Electronic Service Manual page 290

X J
DESCRI PT I ON AN D OPERAT I ON (Cont inue d)
m ot or is r a t ed a t 1.4 kilowa t t s (a bou t 1.9 h or se-
power ) ou t pu t a t 12 volt s.
Bot h of t h ese st a r t er m ot or s a r e ser viced on ly a s a
u n it wit h t h eir st a r t er solen oids, a n d ca n n ot be
r epa ir ed. If eit h er com pon en t is fa u lt y or da m a ged,
t h e en t ir e st a r t er m ot or a n d st a r t er solen oid u n it
m u st be r epla ced.
OPERA TION
Th ese st a r t er m ot or s a r e equ ipped wit h a pla n e-
t a r y gea r r edu ct ion (in t er m edia t e t r a n sm ission ) sys-
t em . Th e pla n et a r y gea r r edu ct ion syst em con sist s of
a gea r t h a t is in t egr a l t o t h e ou t pu t en d of t h e elec-
t r ic m ot or a r m a t u r e sh a ft t h a t is in con t in u a l
en ga gem en t wit h a la r ger gea r t h a t is splin ed t o t h e
in pu t en d of t h e st a r t er pin ion gea r sh a ft . Th is fea -
t u r e m a kes it possible t o r edu ce t h e dim en sion s of
t h e st a r t er. At t h e sa m e t im e, it a llows h igh er a r m a -
t u r e r ot a t ion a l speed a n d deliver s in cr ea sed t or qu e
t h r ou gh t h e st a r t er pin ion gea r t o t h e st a r t er r in g
gea r.
Th e st a r t er m ot or s for bot h en gin es a r e a ct iva t ed
by a n in t egr a l h ea vy du t y st a r t er solen oid swit ch
m ou n t ed t o t h e over r u n n in g clu t ch h ou sin g. Th is
elect r om ech a n ica l swit ch con n ect s a n d discon n ect s
t h e feed of ba t t er y volt a ge t o t h e st a r t er m ot or a n d
a ct u a t es a sh ift for k t h a t en ga ges a n d disen ga ges t h e
st a r t er pin ion gea r wit h t h e st a r t er r in g gea r.
Bot h st a r t er m ot or s u se a n over r u n n in g clu t ch a n d
st a r t er pin ion gea r u n it t o en ga ge a n d dr ive a st a r t er
r in g gea r t h a t is in t egr a l t o t h e flywh eel (m a n u a l
t r a n sm ission ) or t or qu e con ver t er dr ive pla t e (a u t o-
m a t ic t r a n sm ission ) m ou n t ed on t h e r ea r cr a n ksh a ft
fla n ge. Sh im s a r e a va ila ble a n d ca n be u sed t o a dju st
t h e 2.5L st a r t er m ot or m ou n t in g posit ion t o cor r ect
for im pr oper st a r t er pin ion gea r t o st a r t er r in g gea r
en ga gem en t .
STARTER RELA Y
DESCRIPTION
Th e st a r t er r ela y is a n elect r om ech a n ica l device
t h a t swit ch es ba t t er y cu r r en t t o t h e pu ll-in coil of t h e
st a r t er solen oid wh en t h e ign it ion swit ch is t u r n ed t o
t h e St a r t posit ion . Th e st a r t er r ela y is loca t ed in t h e
P ower Dist r ibu t ion Cen t er (P DC), in t h e en gin e com -
pa r t m en t . See t h e fu se a n d r ela y la you t la bel a ffixed
t o t h e in side su r fa ce of t h e P DC cover for st a r t er
r ela y iden t ifica t ion a n d loca t ion .
Th e st a r t er r ela y is a In t er n a t ion a l St a n da r ds
Or ga n iza t ion (ISO) r ela y. Rela ys con for m in g t o t h e
ISO specifica t ion s h a ve com m on ph ysica l dim en sion s,
cu r r en t ca pa cit ies, t er m in a l pa t t er n s, a n d t er m in a l
fu n ct ion s.
Th e st a r t er r ela y ca n n ot be r epa ir ed or a dju st ed
a n d, if fa u lt y or da m a ged, it m u st be r epla ced.
OPERA TION
Th e ISO r ela y con sist s of a n elect r om a gn et ic coil, a
r esist or or diode, a n d t h r ee (t wo fixed a n d on e m ov-
a ble) elect r ica l con t a ct s. Th e m ova ble (com m on feed)
r ela y con t a ct is h eld a ga in st on e of t h e fixed con t a ct s
(n or m a lly closed) by spr in g pr essu r e. Wh en t h e elec-
t r om a gn et ic coil is en er gized, it dr a ws t h e m ova ble
con t a ct a wa y fr om t h e n or m a lly closed fixed con t a ct ,
a n d h olds it a ga in st t h e ot h er (n or m a lly open ) fixed
con t a ct .
Wh en t h e elect r om a gn et ic coil is de-en er gized,
spr in g pr essu r e r et u r n s t h e m ova ble con t a ct t o t h e
n or m a lly closed posit ion . Th e r esist or or diode is con -
n ect ed in pa r a llel wit h t h e elect r om a gn et ic coil in t h e
r ela y, a n d h elps t o dissipa t e volt a ge spikes t h a t a r e
pr odu ced wh en t h e coil is de-en er gized.
DI AGN OSI S AN D T EST I N G
STARTING SYSTEM
DIAGNOSIS
Th e ba t t er y, st a r t in g, a n d ch a r gin g syst em s oper-
a t e wit h on e a n ot h er, a n d m u st be t est ed a s a com -
plet e syst em . In or der for t h e veh icle t o st a r t a n d
ch a r ge pr oper ly, a ll of t h e com pon en t s in volved in
t h ese syst em s m u st per for m wit h in specifica t ion s.
Gr ou p 8A cover s t h e Ba t t er y, Gr ou p 8B cover s t h e
St a r t in g Syst em s, a n d Gr ou p 8C cover s t h e Ch a r gin g
Syst em . We h a ve sepa r a t ed t h ese syst em s t o m a ke it
ea sier t o loca t e t h e in for m a t ion you a r e seekin g
wit h in t h is Ser vice Ma n u a l. H owever, wh en a t t em pt -
in g t o dia gn ose a n y of t h ese syst em s, it is im por t a n t
t h a t you keep t h eir in t er depen den cy in m in d.
Th e dia gn ost ic pr ocedu r es u sed in t h ese gr ou ps
in clu de t h e m ost ba sic con ven t ion a l dia gn ost ic m et h -
ods, t o t h e m or e soph ist ica t ed On -Boa r d Dia gn ost ics
(OBD) bu ilt in t o t h e P ower t r a in Con t r ol Modu le
(P CM). Use of a n in du ct ion -t ype m illia m per e a m m e-
t er, volt /oh m m et er, ba t t er y ch a r ger, ca r bon pile r h eo-
st a t (loa d t est er ), a n d 12-volt t est la m p m a y be
r equ ir ed.
All OBD-sen sed syst em s 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 os-
t ic Tr ou ble Code (DTC). Th e P CM will st or e a DTC in
elect r on ic m em or y for a n y fa ilu r e it det ect s. Refer t o
On -B o a rd D ia g n o s tic Te s t F o r Ch a rg in g S y s te m
in t h e Dia gn osis a n d Test in g sect ion of Gr ou p 8C -
Ch a r gin g Syst em for m or e in for m a t ion .
STARTING SYSTEMS 8B - 3