Jeep Liberty KJ. Manual - part 587

P0506-IDLE SPEED PERFORMANCE LOWER THAN EXCEPTED

For a complete wiring diagram Refer to Section 8W.

Theory of Operation
The objective of the Idle “Speed Rationality is to monitor the ability to achieve and
maintain a steady idle condition. The monitor will judge the functionality of the idle
speed control system by monitoring RPM during idle. If RPM does not come within
a calibrated band of target idle speed, a timer is started. If the timer reaches its
maximum threshold without any sign of the RPM trending towards control, a soft
failure is generated.

•

When Monitored:
With the engine running at idle, MAF <250 mg/tdc, air temp >-17.8°C (0°F) and <-7°C (19.4°F) enable after
coolant temp >70°C (158°F) or air temp >-7°C (19.4°F), coolant temp >-7°C (19.4°F) <130°C (266°F), canister
purge <100% duty cycle, and no VSS, MAF/MAP, ECT, TPS, ETC, CRK Sensor DTCs nor any fuel system or
injector DTCs.

•

Set Condition:
Engine speed is 100 RPM or more below idle speed for 7 seconds. Two Trip Fault. Three good trips to turn off
the MIL.

Possible Causes

AIR INDUCTION SYSTEM

THROTTLE BODY

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).

Diagnostic Test

ACTIVE DTC

NOTE: If any other DTCs are present, they must be diagnosed and repaired before continuing this test.
Ignition on, engine not running.

With a scan tool, read DTCs.

Is the DTC active at this time?

Yes

>> Go To 2

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

AIR INDUCTION SYSTEM

Inspect the Air Induction System for the following problems.

Restrictions: Dirty Air Cleaner, Foreign material trap in the air intake tube, etc.

Leaks: Air Intake tube connection, Air Cleaner housing, etc.

Were any problems found?

Yes

>> Repair or replace as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Go To 3

9 - 406

ENGINE ELECTRICAL DIAGNOSTICS

THROTTLE BODY OPERATION

Inspect the throttle body for carbon build up, other restrictions, and a bent throttle plate using a straight edge.

If the throttle plate does not close entirely it may be bent and needs to be replaced.

Verify that the throttle cable between the Accelerator Pedal and Throttle Body is not binding.

Were any problems found?

Yes

>> Repair or replace as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Go To 4

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)

>> Replace and program the Powertrain Control Module per Service Information.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

ENGINE ELECTRICAL DIAGNOSTICS

9 - 407

P0507-IDLE SPEED PERFORMANCE HIGHER THAN EXCEPTED

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

The objective of the Idle “Speed Rationality is to monitor the ability to achieve and maintain a steady idle condition.
The monitor will judge the functionality of the idle speed control system by monitoring RPM during idle. If RPM does
not come within a calibrated band of target idle speed, a timer is started. If the timer reaches its maximum threshold
without any sign of the RPM trending towards control, a soft failure is generated.

•

Set Condition:
Engine speed is 200 RPM or more above idle speed for 7 seconds. Two Trip Fault. Three good trips to turn off
the MIL.

Possible Causes

AIR INDUCTION SYSTEM

VACUUM LEAKS

THROTTLE BODY

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).

Diagnostic Test

ACTIVE DTC

NOTE: If any other DTCs are present, they must be diagnosed and repaired before continuing this test.
Ignition on, engine not running.

With a scan tool, read DTCs.

Is the DTC active at this time?

Yes

>> Go To 2

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

AIR INDUCTION SYSTEM

Inspect the Air Induction System for the following problems.

Restrictions: Dirty Air Cleaner, Foreign material trap in the air intake tube, etc.

Leaks: Air Intake tube connection, Air Cleaner housing, etc.

Were any problems found?

Yes

>> Repair or replace as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Go To 3

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ENGINE ELECTRICAL DIAGNOSTICS

VACUUM LEAKS

Start the engine.

Inspect the vehicle for external vacuum leaks.

Inspect the engine for internal leaks.

Were any vacuum leaks found?

Yes

>> Repair the vacuum leak as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Go To 4

THROTTLE BODY OPERATION

Inspect the throttle body for carbon build up, other restrictions, and a bent throttle plate using a straight edge.

If the throttle plate does not close entirely it may be bent and needs to be replaced.

Verify that the throttle cable between the Accelerator Pedal and Throttle Body is not binding.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands
near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in
personal injury or death.
While the vehicle is running, lightly tap on IAC Motor, with your hand, and listen for the idle to fluctuate.

Were any problems found?

Yes

>> Repair or replace as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Go To 5

PCM

Were there any problems found?

Yes

>> Repair as necessary.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

>> Replace and program the Powertrain Control Module per Service Information.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

ENGINE ELECTRICAL DIAGNOSTICS

9 - 409

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