Jeep Liberty KJ. Manual — part 466
P0038-O2 SENSOR 1/2 HEATER CIRCUIT HIGH
For a complete wiring diagram Refer to Section 8W.
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ENGINE ELECTRICAL DIAGNOSTICS
KJ
•
When Monitored:
Battery voltage above 10.6 volts, ASD is powered up, and O2 heater is off.
•
Set Condition:
Desired state does not equal Actual state. One Trip Fault. Three good trips to turn off the MIL.
Possible Causes
(K299) O2 1/2 HEATER CONTROL CIRCUIT OPEN
(Z42) O2 1/2 HEATER GROUND CIRCUIT OPEN
(K299) O2 SENSOR 1/2 HEATER CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE
O2 SENSOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.
ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTC’s.
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)
2.
O2 HEATER ELEMENT
Turn the ignition off.
NOTE: Allow the O2 Sensor to cool down to room temperature.
Disconnect the 1/2 O2 Sensor harness connector.
Measure the resistance across the O2 Sensor Heater element, between the Heater Control terminal and the Heater
ground terminal at the component.
NOTE: O2 Heater Element resistance values should be measured at 70°F (21.1°C). The resistance value will
vary with different temperature values.
Is the O2 Sensor Heater Element resistance between 2.0 and 30.0 ohms?
Yes
>> Go To 3
No
>> Replace the O2 Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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ENGINE ELECTRICAL DIAGNOSTICS
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3.
(K299) O2 1/2 HEATER CONTROL CIRCUIT
Ignition on, engine not running.
With a scan tool, actuate the O2 1/2 Heater Test with the O2 Sensor
harness connector still disconnected.
Using a 12-volt test light connected to ground, probe the (K299) O2 1/2
Heater Control circuit in the O2 Sensor harness connector.
Does the test light illuminate brightly and flash on and off dur-
ing the actuation?
Yes
>> Go To 4
No
>> Go To 5
4.
(Z42) O2 HEATER GROUND CIRCUIT OPEN
Turn the ignition off.
Measure the resistance between an engine ground and the (Z42) O2
1/2 Heater ground circuit in the O2 Sensor harness connector.
Is the resistance below 5.0 ohms?
Yes
>> Replace the O2 Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No
>> Repair the open in the (Z42) O2 1/2 Heater ground circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
5.
(K299) O2 1/2 HEATER CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Ignition on, engine not running.
Using a 12-volt test light connect to ground, probe the (K299) O2 1/2
Heater Control circuit in the O2 Sensor harness connector.
Does the test light illuminate brightly?
Yes
>> Repair the short to battery voltage in the (K299) O2 1/2
Heater Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 6
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ENGINE ELECTRICAL DIAGNOSTICS
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6.
(K299) O2 1/2 HEATER CONTROL CIRCUIT OPEN
Turn the ignition off.
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 (K299) O2 1/2 Heater Control circuit from
the O2 Sensor harness connector to the appropriate terminal of special
tool #8815.
Is the resistance below 5.0 ohms?
Yes
>> Go To 7
No
>> Repair the open in the (K299) O2 1/2 Heater Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
7.
PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Yes
>> Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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ENGINE ELECTRICAL DIAGNOSTICS
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