From the '97 FSM, the sensor is physically different but operation is the same and diagnostic procedure should work for '93 4.0L:
CAMSHAFT POSITION SENSOR
The camshaft position sensor is located in the distributor
(Fig. 15) on all engines.
To perform a complete test of this sensor and its
circuitry, refer to the appropriate Powertrain Diagnostics
Procedures service manual. To test the sensor
only, refer to the following:
For this test, an analog (non-digital) voltmeter
is needed. Do not remove the distributor connector
from the distributor. Using small paper clips,
insert them into the backside of the distributor wire
harness connector to make contact with the terminals.
Be sure that the connector is not damaged
when inserting the paper clips. Attach voltmeter
leads to these paper clips.
(1) Connect the positive (+) voltmeter lead into the
sensor output wire. This is at done the distributor
wire harness connector. For wire identification, refer
to Group 8W, Wiring Diagrams.
(2) Connect the negative (-) voltmeter lead into the
ground wire. For wire identification, refer to Group
8W, Wiring Diagrams.
(3) Set the voltmeter to the 15 Volt DC scale.
(4) Remove distributor cap from distributor (two
screws). Rotate (crank) the engine until the distributor
rotor is approximately in the 11 o’clock position.
The movable pulse ring should now be within the
(5) Turn ignition key to ON position. Voltmeter
should read approximately 5.0 volts.
(6) If voltage is not present, check the voltmeter
leads for a good connection.
(7) If voltage is still not present, check for voltage
at the supply wire. For wire identification, refer to
Group 8W, Wiring Diagrams.
(8) If 5 volts is not present at supply wire, check
for voltage at PCM 32-way connector (cavity A-17).
Refer to Group 8W, Wiring for location of connector/
terminal. Leave the PCM connector connected for
(9) If voltage is still not present, perform vehicle
test using the DRB scan tool.
(10) If voltage is present at cavity A-17, but not at
the supply wire:
(a) Check continuity between the supply wire.
This is checked between the distributor connector
and cavity A-17 at the PCM. If continuity is not
present, repair the harness as necessary.
(b) Check for continuity between the camshaft
position sensor output wire and cavity A-18 at the
PCM. If continuity is not present, repair the harness
(c) Check for continuity between the ground circuit
wire at the distributor connector and ground.
If continuity is not present, repair the harness as
(11) While observing the voltmeter, crank the
engine with ignition switch. The voltmeter needle
should fluctuate between 0 and 5 volts while the
engine is cranking. This verifies that the camshaft
position sensor in the distributor is operating properly
and a sync pulse signal is being generated.
If sync pulse signal is not present, replacement of
the camshaft position sensor is necessary