Jeep Liberty KJ. Manual — part 589
P0509-IDLE AIR CONTROL VALVE SENSE CIRCUIT HIGH
For a complete wiring diagram Refer to Section 8W.
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ENGINE ELECTRICAL DIAGNOSTICS
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•
When Monitored:
Engine running. Battery voltage greater than 10 volts. IAC motor operating.
•
Set Condition:
The PCM senses a short to ground or battery voltage on any of the Linear Idle Air Control (LIAC) control
circuits for 2.75 seconds while the IAC motor is active. One Trip Fault. Three good trips to turn off the MIL.
Possible Causes
(K961) IAC RETURN CIRCUIT SHORTED TO BATTERY VOLTAGE
(K61) IAC CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE
(K61) IAC CONTROL CIRCUIT SHORTED TO THE (K961) IAC RETURN CIRCUIT
IAC MOTOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.
IAC MOTOR OPERATION
NOTE: If the engine will not idle, maintain an engine speed between 800 and 1500 RPM.
Start the engine.
Allow the engine to idle.
With a scan tool, read the IAC Current.
Is the IAC Current above 999 mA?
Yes
>> Go To 2
No
>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.
IAC MOTOR
Turn the ignition off.
Disconnect the IAC Motor harness connector.
With the scan tool, monitor the IAC Current.
Ignition on, engine not running.
Does the scan tool display IAC Current at 0 mA?
Yes
>> Replace the IAC Motor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 3
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ENGINE ELECTRICAL DIAGNOSTICS
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3.
(K961) IAC SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C2 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (K961) IAC Signal circuit in the IAC Motor
harness connector.
Is the voltage above 0.5 of a volt?
Yes
>> Repair the short to battery voltage in the (K961) IAC Signal
circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 4
4.
(K61) IAC CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Measure the voltage on the (K61) IAC Control circuit in the IAC Motor
harness connector.
Is the voltage above 0.5 of a volt?
Yes
>> Repair the short to battery voltage in the (K61) IAC Control
circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 5
5.
(K61) IAC CONTROL CIRCUIT SHORTED TO THE (K961) IAC RETURN CIRCUIT
Measure the resistance across the (K961) IAC Signal circuit and the
(K61) IAC Control circuit in the IAC Motor harness connector.
Is the resistance below 5.0 ohms?
Yes
>> Repair the short between the (K961) IAC Signal circuit and
the (K61) IAC 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.
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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