Jeep Cherokee 1999 Electronic Service Manual page 1227

14 - 36 FUEL SYSTEM
DESCRI PT I ON AN D OPERAT I ON (Cont inue d)
does n ot en t er t h e in t a ke m a n ifold t h r ou gh t h e t h r ot -
t le body. F u el is spr a yed in t o t h e m a n ifold by t h e fu el
in ject or s. Th e t h r ot t le body is m ou n t ed on t h e in t a ke
m a n ifold. It con t a in s a n a ir con t r ol pa ssa ge (F ig. 16)
con t r olled by a n Idle Air Con t r ol (IAC) m ot or. Th e a ir
con t r ol pa ssa ge is u sed t o su pply a ir for idle con di-
t ion s. A t h r ot t le va lve (pla t e) is u sed t o su pply a ir for
a bove idle con dit ion s.
Fig. 16 Throttle Body (4.0L Engine Shown)
Th e Th r ot t le P osit ion Sen sor (TP S), IAC m ot or a n d
Ma n ifold Absolu t e P r essu r e
a t t a ch ed t o t h e t h r ot t le body. Th e a cceler a t or peda l
ca ble, speed con t r ol ca ble (wh en equ ipped) a n d a u t o-
m a t ic t r a n sm ission con t r ol ca ble (wh en equ ipped) a r e
con n ect ed t o t h e t h r ot t le a r m .
A (fa ct or y a dju st ed) set scr ew is u sed t o m ech a n i-
ca lly lim it t h e posit ion of t h e t h r ot t le body t h r ot t le
pla t e. N e v e r a tte m p t to a d ju s t th e e n g in e id le
s p e e d u s in g th is s c re w. All idle speed fu n ct ion s a r e
con t r olled by t h e P CM.
DI AGN OSI S AN D T EST I N G
VISUAL INSPECTION
A visu a l in spect ion for loose, discon n ect ed or in cor-
r ect ly r ou t ed wir es a n d h oses sh ou ld be m a de. Th is
sh ou ld be don e befor e a t t em pt in g t o dia gn ose or ser-
vice t h e fu el in ject ion syst em . A visu a l ch eck will
h elp spot t h ese fa u lt s a n d sa ve u n n ecessa r y t est a n d
dia gn ost ic t im e. A t h or ou gh visu a l in spect ion will
in clu de t h e followin g ch ecks:
(1) Ver ify t h e t h r ee 32–wa y elect r ica l con n ect or s
a r e fu lly in ser t ed in t o t h e con n ect or of t h e power-
t r a in con t r ol m odu le (P CM) (F ig. 17).
(2) In spect ba t t er y ca ble con n ect ion s. Be su r e t h ey
a r e clea n a n d t igh t .
sen sor (MAP ) a r e
Fig. 17 Powertrain Control Module (PCM)
(3) In spect fu el pu m p r ela y a n d a ir con dit ion in g
com pr essor clu t ch r ela y (if equ ipped). In spect ASD
r ela y con n ect ion s. In spect st a r t er m ot or r ela y con n ec-
t ion s. In spect r ela ys for sign s of ph ysica l da m a ge a n d
cor r osion . Th e r ela ys a r e loca t ed in P ower Dist r ibu -
t ion Cen t er (P DC) (F ig. 18). Refer t o la bel on P DC
cover for r ela y loca t ion .
Fig. 18 Power Distribution Center (PDC)
(4) In spect ign it ion coil con n ect ion s. Ver ify coil sec-
on da r y ca ble is fir m ly con n ect ed t o coil (F ig. 19) or
(F ig. 20).
(5) Ver ify dist r ibu t or ca p is cor r ect ly a t t a ch ed t o
dist r ibu t or. Be su r e spa r k plu g ca bles a r e fir m ly con -
n ect ed t o dist r ibu t or ca p a n d spa r k plu gs a r e in t h eir
cor r ect fir in g or der. Be su r e coil ca ble is fir m ly con -
n ect ed t o dist r ibu t or ca p a n d coil. Be su r e ca m sh a ft
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