Jeep Grand Cherokee WK. Manual — part 993
P0521-ENGINE OIL PRESSURE SENSOR PERFORMANCE (CONTINUED)
For the Engine System Schematic circuit diagram (Refer to 9 - ENGINE - SCHEMATICS AND DIAGRAMS).
For a complete wiring diagram Refer to Section 8W.
•
When Monitored:
Engine running.
•
Set Condition:
The engine oil pressure never reaches the calibrated specification with the engine RPM at 1250.
Possible Causes
ENGINE OIL/ENGINE MECHANICAL
(G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
RESISTANCE (G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT
(G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN (F855) 5-VOLT SUPPLY CIRCUIT
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE (K900) SENSOR RETURN CIRCUIT
ENGINE OIL PRESSURE SENSOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.
ACTIVE DTC
NOTE: Make sure that the engine oil is at the proper level. Also, check the customers oil change history to
ensure that the oil is being changed at the correct intervals and that the proper oil viscosity is being used.
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Yes
>> Go To 2
No
>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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ENGINE ELECTRICAL DIAGNOSTICS
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P0521-ENGINE OIL PRESSURE SENSOR PERFORMANCE (CONTINUED)
2.
ENGINE OIL/ENGINE MECHANICAL
NOTE: The following items must be considered before determining the cause of this DTC. Failure to do so
may lead to misdiagnosis.
•
ENGINE MECHANICAL TOLERANCES OUT OF SPECIFICATION
•
ENGINE OIL PRESSURE OUT OF SPECIFICATION
•
LOW ENGINE OIL
•
OIL DIRTY OR DETERIORATED (Lack of scheduled oil changes)
•
ENGINE OIL CONTAMINATED (i.e., coolant and/or fuel)
If any of the above conditions are found, repair as necessary.
Were any of the above conditions present?
Yes
>> Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 3
3.
(G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C1 PCM harness connector.
Disconnect the Engine Oil Pressure Sensor harness connector.
Ignition on, engine not running.
Measure the voltage on the (G6) Engine Oil Pressure Signal circuit in
the Engine Oil Pressure Sensor harness connector.
Is the voltage above 0 volts?
Yes
>> Repair the short to battery voltage in the (G6) Engine Oil
Pressure Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 4
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ENGINE ELECTRICAL DIAGNOSTICS
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P0521-ENGINE OIL PRESSURE SENSOR PERFORMANCE (CONTINUED)
4.
ENGINE OIL PRESSURE SENSOR
Turn the ignition off.
Connect the PCM harness connector.
Ignition on, engine not running.
With a scan tool, monitor the Engine Oil Pressure Sensor voltage.
Connect a jumper wire between the (K900) Sensor Ground circuit and
the (G6) Engine Oil Pressure Signal circuit.
NOTE: Engine Oil Pressure voltage should change from approxi-
mately 4.5 volts to less than 0.5 of a volt.
Is the voltage reading within the listed specification when the
jumper wire is installed?
Yes
>> Remove the Engine Oil Pressure sensor and ensure the
oil passage/port is free from any blockage. If OK, replace
the Engine Oil Pressure Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 5
NOTE: Remove the jumper wire before continuing.
5.
EXCESSIVE RESISTANCE IN THE (G6) ENGINE OIL PRESSURE SIGNAL CIRCUIT
Turn the ignition off.
Disconnect the C1 and C2 PCM harness connectors.
CAUTION: Do not probe the PCM harness connectors. Probing
the PCM harness connectors will damage the PCM terminals
resulting in poor terminal to pin connection. Install Miller Special
Tool #8815 to perform diagnosis.
Measure the resistance of the (G6) Engine Oil Pressure Signal circuit
from the Engine Oil Pressure Sensor harness connector to the appro-
priate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
>> Go To 6
No
>> Repair the excessive resistance in the (G6) Engine Oil
Pressure Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
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ENGINE ELECTRICAL DIAGNOSTICS
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P0521-ENGINE OIL PRESSURE SENSOR PERFORMANCE (CONTINUED)
6.
(G6) ENGINE OIL PRESSURE SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (G6) Engine Oil Pres-
sure Signal circuit Engine Oil Pressure Sensor harness connector.
Is the resistance below 100 ohms?
Yes
>> Repair the short to ground in the (G6) Engine Oil Pressure
Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 7
7.
EXCESSIVE RESISTANCE IN THE (F855) 5–VOLT SUPPLY CIRCUIT
Measure the resistance of the (F855) 5-volt Supply circuit from the
Engine Oil Pressure Sensor harness connector to the appropriate ter-
minal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
>> Go To 8
No
>> Repair the excessive resistance in the (F855) 5-volt Sup-
ply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
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ENGINE ELECTRICAL DIAGNOSTICS
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