Jeep Cherokee 1999 Electronic Service Manual page 1250

X J
DESCRI PT I ON AN D OPERAT I ON (Cont inue d)
Fig. 8 Fuel Heater Temperature Sensor and Element
a ddit ion a l in for m a t ion . Th e fu e l h e a te r a n d fu e l
h e a te r re la y a re n o t c o n tro lle d by th e P o w e r-
tra in Co n tro l Mo d u le (ECM).
Cu r r en t dr a w for t h e h ea t er elem en t is 150 wa t t s
a t 14 volt s (DC).
FUEL HEA TER RELA Y
Volt a ge t o oper a t e t h e fu el h ea t er is su pplied fr om
t h e ign it ion (key) swit ch t h r ou gh t h e fu el h ea t er
r ela y. Th e P CM o r MS A is n o t u s e d to c o n tro l
th is re la y.
Th e fu el h ea t er r ela y is loca t ed in t h e P DC. Th e
P DC is loca t ed n ext t o t h e ba t t er y in t h e en gin e com -
pa r t m en t . F or t h e loca t ion of t h e r ela y wit h in t h e
P DC, r efer t o la bel on P DC cover.
DI AGN OSI S AN D T EST I N G
GENERAL INFORMA TION
Th is sect ion of t h e gr ou p will cover a gen er a l dia g-
n osis of diesel en gin e fu el syst em com pon en t s.
D ia g n o s tic Tro u ble Co d e 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 a list of Dia gn ost ic Tr ou ble Codes (DTC's) for cer-
t a in fu el syst em com pon en t s.
Th e P CM a n d MSA m u st be t est ed wit h t h e
DRBIII sca n t ool. Th e DRBIII sh ou ld be t h e fir st
st ep in a n y dia gn osis of en gin e per for m a n ce com -
pla in t s. Refer t o t h e 1997 ZJ /ZG 2.5L Diesel P ower-
t r a in Dia gn ost ic P r ocedu r es m a n u a l for dia gn osis
a n d t est in g of t h e diesel en gin e con t r ol syst em .
Location
FUEL SYSTEM—2.5L DIESEL ENGINE
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 befor e
a t t em pt in g t o dia gn ose or ser vice t h e diesel fu el
in ject ion syst em . A visu a l ch eck will h elp fin d t h ese
con dit ion s. It a lso sa ves u n n ecessa r y t est a n d dia g-
n ost ic t im e. A t h or ou gh visu a l in spect ion of t h e fu el
in ject ion syst em in clu des t h e followin g ch ecks:
(1) Be su r e t h a t t h e ba t t er y con n ect ion s a r e t igh t
a n d n ot cor r oded.
(2) Be su r e t h a t t h e 60 wa y con n ect or is fu lly
en ga ged wit h t h e P CM (F ig. 9).
(3) Be su r e t h a t t h e 68 wa y con n ect or is fu lly
en ga ged wit h t h e MSA (F ig. 10).
Fig. 9 PCM Location—Typical
(4) Ver ify t h a t t h e elect r ica l con n ect ion s for t h e
ASD r ela y a r e clea n a n d fr ee of cor r osion . Th is r ela y
is loca t ed in t h e P DC. F or t h e loca t ion of t h e r ela y
wit h in t h e P DC, r efer t o la bel on P DC cover.
(5) Ver ify t h a t t h e elect r ica l con n ect ion s for t h e
fu el h ea t er r ela y a r e clea n a n d fr ee of cor r osion . Th is
r ela y is loca t ed in t h e P DC. F or t h e loca t ion of t h e
r ela y wit h in t h e P DC, r efer t o la bel on P DC cover.
(6) Be su r e t h e elect r ica l con n ect or s a t t h e en ds of
t h e glow plu gs (F ig. 11) a r e t igh t a n d fr ee of cor r o-
sion .
(7) Be su r e t h a t t h e elect r ica l con n ect ion s a t t h e
glow plu g r ela y a r e t igh t a n d n ot cor r oded. Th e glow
plu g r ela y is loca t ed in t h e en gin e com pa r t m en t on
t h e left –in n er fen der (F ig. 12).
(8) In spect t h e st a r t er m ot or a n d st a r t er solen oid
con n ect ion s for t igh t n ess a n d cor r osion .
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