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80 - 8
IGNITION SYSTEM
DIAGNOSIS AND TESTING (Continued)
Fig. 16 Cap Inspection-External-Typical
Fig. 17 Cap Inspection-Internal-Typical
IGNITION TIMING
DISTRIBUTOR ROTOR
Visually inspect the rotor (Fig . 18) for cracks, evi-
dence of corrosion or the effects of arcing on the
metal tip . Also check for evidence of mechanical
interference with the cap . Some charring is normal
on the end of the metal tip . The silicone-dielectric-
varnish-compound applied to the rotor tip for radio
interference noise suppression, will appear charred.
This is normal . Do not remove the charred com-
pound. Test the spring for insufficient tension .
Replace a rotor that displays any of these adverse
conditions.
NOTE: Base (initial) ignition timing is NOT adjust-
able on any 2.5L 4-cylinder or 4.OL 6-cylinder
engine . Do not attempt to adjust ignition timing by
rotating the distributor.
INSUFFICIENT
SPRING
TENSION
ROTOR
TIP
CORRODED
EVIDENCE OF
PHYSICAL
CONTACT
WITH CAP
J908D-48
Fig. 18 Rotor Inspection-Typical
TJ
NOTE:
Do not attempt to modify the distributor
housing to get distributor rotation. Distributor posi-
tion will have no effect on ignition timing.
All ignition timing functions are controlled by the
powertrain control module (PCM). For additional
information, refer to the appropriate Powertrain
Diagnostics Procedures service manual for operation
of the DRB Scan Tool .
MAP SENSOR
For an operational description, diagnosis or remov-
al/ installation procedures, refer to Group 14, Fuel
Systems .
CRANKSHAFT POSITION SENSOR TEST
To perform a complete test of this sensor and its
circuitry, refer to the DRB scan tool. Also refer to the
appropriate Powertrain Diagnostics Procedures man-
ual . To test the sensor only, refer to the following :
The crankshaft position sensor is mounted to the
transmission bellhousing at the left/rear side of the
engine block (Fig. 19), (Fig . 20), or (Fig . 21) .
(1) Near the rear of the intake manifold, discon-
nect sensor pigtail harness connector from main wir-
ing harness (Fig . 19), (Fig . 20), or (Fig . 21) .
(2) Place an ohmmeter across terminals B and C
(Fig. 22) . Ohmmeter should be set to 1K-to-10K scale
for this test. The meter reading should be open (high
resistance) . Replace sensor if a low resistance is indi-
cated .
CAMSHAFT POSITION SENSOR
The camshaft position sensor is located in the dis-
tributor (Fig. 23) on all engines .
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Table of Contents
Troubleshooting
