Jeep Cherokee 1999 Electronic Service Manual page 1397

21 - 74 TRANSMISSION AND TRANSFER CASE
GEN ERAL I N FORM AT I ON
30RH AUTOMA TIC TRANSMISSION
Th e 30RH a u t om a t ic t r a n sm ission is u sed wit h t h e
2.5L en gin e (F ig. 1). Th e 30RH is a t h r ee speed
t r a n sm ission s wit h a lock-u p clu t ch in t h e t or qu e
con ver t er. Th e t or qu e con ver t er clu t ch is con t r olled
by t h e P ower t r a in Con t r ol Modu le (P CM). Th e t or qu e
con ver t er clu t ch is h ydr a u lica lly a pplied a n d is
r elea sed wh en flu id is ven t ed fr om t h e h ydr a u lic cir-
cu it by t h e t or qu e con ver t er con t r ol (TCC) solen oid
on t h e va lve body. Th e t or qu e con ver t er clu t ch
en ga ges in t h ir d gea r wh en t h e veh icle is cr u isin g on
a level pla n e a ft er t h e veh icle h a s wa r m ed u p. Th e
t or qu e con ver t er clu t ch will disen ga ge wh en t h e veh i-
cle begin s t o go u ph ill or t h e a cceler a t or is a pplied.
Th e t or qu e con ver t er clu t ch fea t u r e in cr ea ses fu el
econ om y a n d r edu ces t h e t r a n sm ission flu id t em per-
a t u r e. Th e 30RH t r a n sm ission is cooled by a n in t e-
gr a l flu id cooler in side t h e r a dia t or.
TRANSMISSION IDENTIFICA TION
Tr a n sm ission iden t ifica t ion n u m ber s a r e st a m ped
on t h e left side of t h e ca se ju st a bove t h e oil pa n ga s-
ket su r fa ce (F ig. 2). Refer t o t h is in for m a t ion wh en
or der in g r epla cem en t pa r t s.
RECOMMENDED FLUID
Mopa r ATF P lu s 3, Type 7176 a u t om a t ic t r a n s-
m ission flu id is t h e r ecom m en ded flu id for Ch r ysler
a u t om a t ic t r a n sm ission s.
D e x ro n II flu id IS N OT re c o m m e n d e d . Clu tc h
c h a tte r c a n re s u lt fro m th e u s e o f im p ro p e r
flu id .
EFFECTS OF INCORRECT FLUID LEVEL
A low flu id level a llows t h e pu m p t o t a ke in a ir
a lon g wit h t h e flu id. Air in t h e flu id will ca u se flu id
pr essu r es t o be low a n d develop slower t h a n n or m a l.
If t h e t r a n sm ission is over filled, t h e gea r s ch u r n t h e
flu id in t o foa m . Th is a er a t es t h e flu id a n d ca u sin g
t h e sa m e con dit ion s occu r r in g wit h a low level. In
eit h er ca se, a ir bu bbles ca u se flu id over h ea t in g, oxi-
da t ion a n d va r n ish bu ildu p wh ich in t er fer es wit h
va lve, clu t ch a n d ser vo oper a t ion . F oa m in g a lso
ca u ses flu id expa n sion wh ich ca n r esu lt in flu id over-
flow fr om t h e t r a n sm ission ven t or fill t u be. F lu id
over flow ca n ea sily be m ist a ken for a lea k if in spec-
t ion is n ot ca r efu l.
CAUSES OF BURNT FLUID
Bu r n t , discolor ed flu id is a r esu lt of over h ea t in g
wh ich h a s t wo pr im a r y ca u ses.
(1) A r esu lt of r est r ict ed flu id flow t h r ou gh t h e
m a in a n d/or a u xilia r y cooler. Th is con dit ion is u su -
a lly t h e r esu lt of a fa u lt y or im pr oper ly in st a lled
dr a in ba ck va lve, a da m a ged m a in cooler, or sever e
r est r ict ion s in t h e cooler s a n d lin es ca u sed by debr is
or kin ked lin es.
(2) H ea vy du t y oper a t ion wit h a veh icle n ot pr op-
er ly equ ipped for t h is t ype of oper a t ion . Tr a iler t ow-
in g or sim ila r h igh loa d oper a t ion will over h ea t t h e
t r a n sm ission flu id if t h e veh icle is im pr oper ly
equ ipped. Su ch veh icles sh ou ld h a ve a n a u xilia r y
t r a n sm ission flu id cooler, a h ea vy du t y coolin g sys-
t em , a n d t h e en gin e/a xle r a t io com bin a t ion n eeded t o
h a n dle h ea vy loa ds.
FLUID CONTAMINA TION
Tr a n sm ission flu id con t a m in a t ion is gen er a lly a
r esu lt of:
• a ddin g in cor r ect flu id
• fa ilu r e t o clea n dipst ick a n d fill t u be wh en
ch eckin g level
• en gin e coola n t en t er in g t h e flu id
• in t er n a l fa ilu r e t h a t gen er a t es debr is
• over h ea t t h a t gen er a t es slu dge (flu id br ea k-
down )
• fa ilu r e t o r ever se flu sh cooler a n d lin es a ft er
r epa ir
• fa ilu r e t o r epla ce con t a m in a t ed con ver t er a ft er
r epa ir.
Th e u se of n on r ecom m en ded flu ids ca n r esu lt in
t r a n sm ission fa ilu r e. Th e u su a l r esu lt s a r e er r a t ic
sh ift s, slippa ge, a bn or m a l wea r a n d even t u a l fa ilu r e
du e t o flu id br ea kdown a n d slu dge for m a t ion . Avoid
t h is con dit ion by u sin g r ecom m en ded flu ids on ly.
Th e dipst ick ca p a n d fill t u be sh ou ld be wiped
clea n befor e ch eckin g flu id level. Dir t , gr ea se a n d
ot h er for eign m a t er ia l on t h e ca p a n d t u be cou ld fa ll
in t o t h e t u be if n ot r em oved befor eh a n d. Ta ke t h e
t im e t o wipe t h e ca p a n d t u be clea n befor e wit h dr a w-
in g t h e dipst ick.
E n gin e coola n t in t h e t r a n sm ission flu id is gen er-
a lly ca u sed by a cooler m a lfu n ct ion . Th e on ly r em edy
is t o r epla ce t h e r a dia t or a s t h e cooler in t h e r a dia t or
is n ot a ser vicea ble pa r t . If coola n t h a s cir cu la t ed
t h r ou gh t h e t r a n sm ission for som e t im e, a n over h a u l
m a y a lso be n ecessa r y; especia lly if sh ift pr oblem s
h a d developed.
Th e t r a n sm ission cooler a n d lin es sh ou ld be
r ever se flu sh ed wh en ever a m a lfu n ct ion gen er a t es
slu dge a n d/or debr is. Th e t or qu e con ver t er sh ou ld
a lso be r epla ced a t t h e sa m e t im e.
F a ilu r e t o flu sh t h e cooler a n d lin es will r esu lt in
r econ t a m in a t ion . F lu sh in g a pplies t o a u xilia r y cool-
er s a s well. Th e t or qu e con ver t er sh ou ld a lso be
r epla ced wh en ever a fa ilu r e gen er a t es slu dge a n d
debr is. Th is is n ecessa r y beca u se n or m a l con ver t er
flu sh in g pr ocedu r es will n ot r em ove a ll con t a m i-
n a n t s.
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