Jeep Cherokee 1999 Electronic Service Manual page 1231

14 - 40 FUEL SYSTEM
DI AGN OSI S AN D T EST I N G (Cont inue d)
Fig. 30 ASD and Fuel Pump Relay Terminals
Fig. 31 ASD and Fuel Pump Relay Terminals
• Wh en t h e P CM en er gizes t h e ASD a n d fu el
pu m p r ela ys, t er m in a l 87 con n ect s t o t er m in a l 30.
Th is is t h e On posit ion . Ter m in a l 87 su pplies volt a ge
t o t h e r est of t h e cir cu it .
TESTING
Th e followin g pr ocedu r e a pplies t o t h e ASD a n d
fu el pu m p r ela ys.
(1) Rem ove r ela y fr om con n ect or befor e t est in g.
(2) Wit h t h e r ela y r em oved fr om t h e veh icle, u se
a n oh m m et er t o ch eck t h e r esist a n ce bet ween t er m i-
n a ls 85 a n d 86. Th e r esist a n ce sh ou ld be bet ween 75
5 oh m s.
(3) Con n ect t h e oh m m et er bet ween t er m in a ls 30
a n d 87A. Th e oh m m et er sh ou ld sh ow con t in u it y
bet ween t er m in a ls 30 a n d 87A.
(4) Con n ect t h e oh m m et er bet ween t er m in a ls 87
a n d 30. Th e oh m m et er sh ou ld n ot sh ow con t in u it y a t
t h is t im e.
(5) Con n ect on e en d of a ju m per wir e (16 ga u ge or
sm a ller ) t o r ela y t er m in a l 85. Con n ect t h e ot h er en d
of t h e ju m per wir e t o t h e gr ou n d side of a 12 volt
power sou r ce.
(6) Con n ect on e en d of a n ot h er ju m per wir e (16
ga u ge or sm a ller ) t o t h e power side of t h e 12 volt
power sou r ce. D o n o t a tta c h th e o th e r e n d o f th e
ju m p e r w ire to th e re la y a t th is tim e .
WARNING: DO NOT ALLOW OHMMETER TO CON-
TACT TERMINALS 85 OR 86 DURING THIS TEST.
(7) At t a ch t h e ot h er en d of t h e ju m per wir e t o
r ela y t er m in a l 86. Th is a ct iva t es t h e r ela y. Th e oh m -
m et er sh ou ld n ow sh ow con t in u it y bet ween r ela y t er-
m in a ls 87 a n d 30. Th e oh m m et er sh ou ld n ot sh ow
con t in u it y bet ween r ela y t er m in a ls 87A a n d 30.
(8) Discon n ect ju m per wir es.
(9) Repla ce t h e r ela y if it did n ot pa ss t h e con t in u -
it y a n d r esist a n ce t est s. If t h e r ela y pa ssed t h e t est s,
it oper a t es pr oper ly. Ch eck t h e r em a in der of t h e ASD
a n d fu el pu m p r ela y cir cu it s. Refer t o t h e Wir in g
Dia gr a m s.
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSOR TEST
To per for m a com plet e t est of MAP sen sor (F ig. 32)
a n d it s cir cu it r y, r efer t o DRB sca n t ool a n d a ppr o-
pr ia t e P ower t r a in Dia gn ost ics P r ocedu r es m a n u a l. To
t est t h e MAP sen sor on ly, r efer t o t h e followin g:
(1) In spect r u bber L-sh a ped fit t in g fr om MAP sen -
sor t o t h r ot t le body (F ig. 33). Repa ir a s n ecessa r y.
Fig. 32 Sensor Location (4.0L Engine Shown)
CAUTION: When testing the MAP sensor, be sure
that the harness wires are not damaged by the test
meter probes.
(2) Test MAP sen sor ou t pu t volt a ge a t MAP sen sor
con n ect or bet ween t er m in a ls A a n d B (F ig. 34). Wit h
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