Jeep XJ. Manual — part 356
RELAYS—OPERATION/TESTING
The following description of operation and
tests apply only to the ASD and other relays.
The terminals on the bottom of each relay are num-
bered (Fig. 19).
OPERATION
• Terminal number 30 is connected to battery volt-
age. For both the ASD and other relays, terminal 30
is connected to battery voltage at all times.
• The ECM grounds the coil side of the relay
through terminal number 85.
• Terminal number 86 supplies voltage to the coil
side of the relay.
• When the PCM de-energizes the ASD and other
relays, terminal number 87A connects to terminal 30.
This is the Off position. In the off position, voltage is
not supplied to the rest of the circuit. Terminal 87A
is the center terminal on the relay.
• When the ECM energizes the ASD and other
relays, terminal 87 connects to terminal 30. This is
the On position. Terminal 87 supplies voltage to the
rest of the circuit.
TESTING
The following procedure applies to the ASD and
other relays.
(1) Remove relay from connector before testing.
(2) With the relay removed from the vehicle, use
an ohmmeter to check the resistance between termi-
nals 85 and 86. The resistance should be between 75
65 ohms.
(3) Connect the ohmmeter between terminals 30
and 87A. The ohmmeter should show continuity
between terminals 30 and 87A.
(4) Connect the ohmmeter between terminals 87
and 30. The ohmmeter should not show continuity at
this time.
(5) Connect one end of a jumper wire (16 gauge or
smaller) to relay terminal 85. Connect the other end
of the jumper wire to the ground side of a 12 volt
power source.
(6) Connect one end of another jumper wire (16
gauge or smaller) to the power side of the 12 volt
power source. Do not attach the other end of the
jumper wire to the relay at this time.
WARNING: DO NOT ALLOW OHMMETER TO CON-
TACT TERMINALS 85 OR 86 DURING THIS TEST.
(7) Attach the other end of the jumper wire to
relay terminal 86. This activates the relay. The ohm-
meter should now show continuity between relay ter-
minals 87 and 30. The ohmmeter should not show
continuity between relay terminals 87A and 30.
(8) Disconnect jumper wires.
(9) Replace the relay if it did not pass the continu-
ity and resistance tests. If the relay passed the tests,
it operates properly. Check the remainder of the ASD
and other relay circuits. Refer to group 8W, Wiring
Diagrams.
BOOST / PRESSURE SENSOR
If the boost pressure sensor fails, the PCM records
a DTC into memory and continues to operate the
Fig. 19 Glow Plug Relay Location
1 – MOUNTING BOLT
2 – GLOW PLUG RELAY
3 – ELECTRICAL CONNECTOR
Fig. 20 Boost Pressure Sensor Location
1 – BOOST PRESSURE SENSOR HARNESS CONNECTOR
2 – BOOST PRESSURE SENSOR
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FUEL SYSTEM—2.5L DIESEL ENGINE
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DIAGNOSIS AND TESTING (Continued)
2000 JEEP CHEROKEE
engine in one of the three “limp-in” modes. When the
PCM is operating in this mode, a loss of power will
be present, as if the turbocharger was not operating.
The best method for diagnosing faults with the boost
pressure sensor is with the DRB III scan tool. Diag-
nostic Trouble Codes: Refer to On-Board Diagnos-
tics in Group 25, Emission Control System for a list
of Diagnostic Trouble Codes (DTC’s) for certain fuel
system components.
VEHICLE SPEED SENSOR TEST
To perform a test of the sensor and its related cir-
cuitry, refer to DRB scan tool.
Diagnostic Trouble Codes: Refer to On-Board
Diagnostics in Group 25, Emission Control System
for a list of Diagnostic Trouble Codes (DTC’s) for cer-
tain fuel system components.
DIAGNOSTIC TROUBLE CODES
For a list of Diagnostic Trouble Codes (DTC’s),
refer to Group 25, Emission Control System for infor-
mation. See On-Board Diagnostics.
REMOVAL AND INSTALLATION
ASD RELAY
The ASD relay is located in the PDC. For the loca-
tion of the relay within the PDC, refer to label on
PDC cover.
A/C CLUTCH RELAY
The A/C clutch relay is located in the PDC. For the
location of the relay within the PDC, refer to label on
PDC cover.
ENGINE SPEED SENSOR
The engine speed sensor is mounted to the trans-
mission bellhousing at the rear of the engine block
(Fig. 21).
REMOVAL
(1) Disconnect the harness (on the sensor) from
the main electrical harness.
(2) Remove the sensor mounting bolts.
(3) Remove the sensor.
INSTALLATION
(1) Install the sensor flush against the opening in
the transmission housing.
(2) Install and tighten the sensor mounting bolt to
19 N·m (14 ft. lbs.) torque.
(3) Connect the electrical connector to the sensor.
ENGINE COOLANT TEMPERATURE SENSOR
The sensor is located on the side of cylinder head
near the rear of fuel injection pump.
REMOVAL
WARNING: HOT,
PRESSURIZED
COOLANT
CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING
THE
COOLANT
TEMPERATURE
SENSOR.
REFER TO GROUP 7, COOLING.
(1) Partially drain cooling system. Refer to Group
7, Cooling.
(2) Disconnect electrical connector from sensor.
(3) Remove sensor from cylinder head.
INSTALLATION
(1) Install a new copper gasket to sensor.
(2) Install sensor to cylinder head.
(3) Tighten sensor to 18 N·m (13 ft. lbs.) torque.
(4) Connect electrical connector to sensor.
(5) Replace any lost engine coolant. Refer to Group
7, Cooling System.
GLOW PLUGS
The glow plugs are located above each fuel injector
(Fig. 22). Four individual plugs are used.
REMOVAL
(1) Disconnect the negative battery cable at the
battery.
(2) Clean the area around the glow plug with com-
pressed air before removal.
Fig. 21 Engine Speed Sensor
1 – ENGINE SPEED SENSOR
2 – GROMMET
3 – MOUNTING BOLT(S)
4 – LEFT REAR OF ENGINE
5 – TRANSMISSION
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FUEL SYSTEM—2.5L DIESEL ENGINE
14 - 35
DIAGNOSIS AND TESTING (Continued)
2000 JEEP CHEROKEE
(3) Disconnect electrical connector (Fig. 23) at glow
plug.
(4) Remove the glow plug (Fig. 22) from cylinder
head.
INSTALLATION
(1) Apply high–temperature anti–seize compound
to glow plug threads before installation
(2) Install the glow plug into the cylinder head.
Tighten to 14 N·m (123 in. lbs.) torque.
(3) Connect battery cable to battery.
GLOW PLUG RELAY
The glow plug relay is located in the engine com-
partment on the left–inner fender (Fig. 24).
REMOVAL
(1) Disconnect the negative battery cable at the
battery.
(2) Remove relay mounting bolt.
(3) Disconnect electrical connector at relay and
remove relay.
INSTALLATION
(1) Check condition of electrical connector for dam-
age or corrosion. Repair as necessary.
(2) Install electrical connector to relay.
(3) Install relay to inner fender.
(4) Connect battery cable to battery.
POWERTRAIN CONTROL MODULE (PCM)
The PCM is mounted to a bracket mounted to the
inner side of the right fender well behind the air
cleaner assembly. (Fig. 25).
REMOVAL
(1) Disconnect the negative battery cable at the
battery.
(2) Loosen the 60–Way connector (Fig. 25). The
electrical connector has a sliding bar which moves
inward to lock or outward to unlock.
(3) Remove the electrical connector by pulling
straight out.
(4) Remove PCM.
INSTALLATION
(1) After the PCM electrical connector has been
separated from the PCM, inspect the pins for corro-
Fig. 22 Glow Plug
1 – GLOW PLUG
Fig. 23 Glow Plug Electrical Connector
1 – GLOW PLUG ELECTRICAL CONNECTOR
Fig. 24 Glow Plug Relay Location
1 – MOUNTING BOLT
2 – GLOW PLUG RELAY
3 – ELECTRICAL CONNECTOR
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FUEL SYSTEM—2.5L DIESEL ENGINE
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REMOVAL AND INSTALLATION (Continued)
2000 JEEP CHEROKEE
sion, being spread apart, bent or misaligned. Also
inspect the pin heights in the connector. If the pin
heights are different, this would indicate a pin has
separated from the connector. Repair as necessary.
(2) Engage 60–way connector into PCM. Move
slide bar to lock connector.
(3) Connect negative cable to battery.
VEHICLE SPEED SENSOR
The vehicle speed sensor is located in the transfer
case housing for 4 wheel drive vehicles (Fig. 26).
REMOVAL
(1) Raise and support vehicle.
(2) Clean the area around the sensor before
removal.
(3) Disconnect the electrical connector from the
sensor (Fig. 27).
(4) Remove the sensor mounting bolt (Fig. 27).
(5) Pull the sensor from the speedometer pinion
gear adapter for removal.
INSTALLATION
(1) Install
new
sensor
into
speedometer
gear
adapter.
(2) Tighten sensor mounting bolt. To prevent dam-
age to sensor or speedometer adapter, be sure the
sensor is mounted flush to the adapter before tight-
ening.
(3) Connect electrical connector to sensor.
Fig. 25 PCM Location
1 – PCM HARNESS CONNECTOR C1
2 – PCM HARNESS CONNECTOR C2
3 – PCM HARNESS CONNECTOR C3
4 – POWERTRAIN CONTROL MODULE (PCM)
Fig. 26 Vehicle Speed Sensor Location—4WD
1 – SENSOR ELECTRICAL CONNECTOR
2 – 4WD TRANSFER CASE EXTENSION
3 – VEHICLE SPEED SENSOR
Fig. 27 Sensor Removal/Installation—Typical
1 – ELECTRICAL CONNECTOR
2 – SENSOR MOUNTING BOLT
3 – O-RING
4 – SPEEDOMETER PINION GEAR
5 – SPEEDOMETER PINION GEAR ADAPTER
6 – O-RING
7 – VEHICLE SPEED SENSOR
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FUEL SYSTEM—2.5L DIESEL ENGINE
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REMOVAL AND INSTALLATION (Continued)
2000 JEEP CHEROKEE
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