Jeep Wrangler 1997 Manual page 800

14- 28 FUEL SYSTEM
DESCRIPTION AND OPERATION (Continued)
IDLE AIR CONTROL
PASSAGE INLET
MAP
SENSOR
Fig, 13 Throttle Body
DIAGNOSIS AND TESTING
IDLE AIR CONTROL MOTOR
INTAKE MANIFOLD
AIR TEMPERATURE
SENSOR
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matic transmission control cable (when equipped) are
connected to the throttle arm.
A (factory adjusted) set screw
is
used to mechani-
cally limit the position of the throttle body throttle
plate. Never attempt to adjust the engine idle
speed using this screw . All idle speed functions are
controlled by the PCM.
VISUAL INSPECTION
A visual inspection for loose, disconnected or incor-
rectly routed wires and hoses should be made . This
should be done before attempting to diagnose or ser-
vice the fuel injection system . A visual check will
help spot these faults and save unnecessary test and
diagnostic time . A thorough visual inspection will
include the following checks :
(1) Verify that the three 32-way electrical connec-
tors are fully inserted into connector of Powertrain
Control Module (PCM) (Fig. 14).
(2) Inspect battery cable connections. Be sure that
they are clean and tight.
(3) Inspect fuel pump relay and ASD relay connec-
tions. Inspect starter motor relay connections .
Inspect relays for signs of physical damage and cor-
rosion . The relays are located in Power Distribution
Center (PDC) (Fig . 15). Refer to label on PDC cover
for relay location.
(4) Inspect ignition coil connections. Verify that
coil secondary cable is firmly connected to coil (Fig.
16) .
(5) Verify that distributor cap is correctly attached
to distributor. Be sure that spark plug cables are
firmly connected to the distributor cap and spark
plugs are in their correct firing order (Fig . 17). Be
sure that coil cable is firmly connected to distributor
cap and coil. Be sure that camshaft position sensor
PCM
MOUNTING
BOLTS (3)
(3) 32-WAY
CONNECTOR\
Fig. 14 Powertrain Control Module (PCM)
Fig. 15 Power Distribution Center (PDC)
TJ
POWERTRAIN
CONTROL MODULE
(PCM) f\--,
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POWER DISTRIBUTION
CENTE\\\
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wire connector (at distributor) is firmly connected to
harness connector. Inspect spark plug condition .
Refer to Group 8D, Ignition . Connect vehicle to an
oscilloscope and inspect spark events for fouled or
damaged spark plugs or cables .
(6) Verify that generator output wire, generator
connector and ground wire are firmly connected to
the generator.
(7) Inspect system body grounds for loose or dirty
connections. Refer to Group 8, Wiring for ground
locations.
(8) Verify Crankcase Ventilation (CCV) operation.
Refer to Group 25, Emission Control System for addi-
tional information.
(9) Inspect fuel tube quick-connect fitting-to-fuel
rail connections.