DaimlerChrysler Jeep Grand Cherokee 2002, Service Manual

Page: 121 / 284

POSSIBLE CAUSES
ECM - A/C PRESSURE SENSOR SIGNAL
ECM - SENSOR REFERENCE VOLTAGE B CIRCUIT
ECM - SIGNAL VOLTAGE HIGH
TEST ACTION APPLICABILITY
1 NOTE: If DTC P0641 or P0651 is present with this DTC, diagnose DTCs
P0641 and P0651 before diagnosing this DTC.
NOTE: Ensure the A/C refrigerant System is properly charged per the
Service Information.
Start the engine.
With the DRBIII
t
, read the A/C Pressure Sensor voltage.
Select the choice that best reflects the DRBIII
t
reading.
All
Above 4.6 volts
Go To 2
Between 0.7 and 4.6 volts
Go To 9
Below 0.7 volt
Go To 10
2 Turn the ignition off.
Disconnect the A/C Pressure Sensor harness connector.
Disconnect the ECM harness connector.
Measure the resistance between the A/C Pressure Sensor Signal circuit and the 5-volt
Supply circuit in the A/C Pressure Sensor harness connector.
Is the resistance above 100 kohms? All
Yes
→
Go To 3
No
→
Repair the A/C Pressure Sensor Signal circuit for a short to the
5-volt Supply circuit.
Perform ROAD TEST VERIFICATION - VER-2.
3 Turn the ignition off.
Disconnect the A/C Pressure Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the ASD Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.
Turn the ignition on.
Measure the voltage of the Sensor Ground circuit at the A/C Pressure Sensor and
ECM harness connectors.
Is the voltage above 1.0 volt at either connector? All
Yes
→
Repair the A/C Pressure Sensor Ground circuit for a short to
voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No
→
Go To 4
NOTE: If the Sensor Ground circuit had a short to voltage on it, the ECM
may have been damaged. Retest the A/C Pressure Sensor circuit.
113
DRIVEABILITY - DIESEL
P0530-A/C PRESSURE SENSOR CIRCUIT SIGNAL VOLTAGE TOO HIGH
—
Continued
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