P0506

P0506-IDLE SPEED PERFORMANCE LOWER THAN EXCEPTED

For a complete wiring diagram refer to Diagrams/Electrical.

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 dead 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 greater then 250 mg/tdc, air temp greater then -17.8° C (0° F) and less then -7° C (19.4° F) enable after coolant temp greater then 70° C (158° F) or air temp greater then -7° C (19.4° F), coolant temp greater then -7° C (19.4° F) less then 130° C (266° F), canister purge less then 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.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.


Diagnostic Test

1. ACTIVE DTC

NOTE: If any other IAC Motor or Throttle Body DTCs are present, they must be diagnosed and repaired before continuing this test.

Start the engine.

Allow the engine to reach normal operating temperature.

With a scan tool, select View DTCs.

NOTE: It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.

Is the DTC Active or Pending at this time?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

2. AIR INDUCTION SYSTEM

Inspect the Air Induction System for the following problems.

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

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

Remove the IAC Motor where applicable and check the IAC passages for restrictions.

Were any problems found?

Yes

- Repair or replace as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 3


3. PCV SYSTEM

Inspect the PCV system for the following problems:

Restrictions - sticking valve, collapsed hoses or tubes, obstructed passages or ports, etc.

Leaks - cracked or damaged hoses or tubes, poor hose or tube connections, PCV valve stuck open, etc.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 4


4. THROTTLE BODY OPERATION / IAC MOTOR 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 APPS is not binding on ETC equipped vehicles.

Verify that the throttle cable between the Accelerator Pedal and Throttle Body is not binding on IAC equipped vehicles.

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 ETC Motor or IAC Motor where applicable, with your hand, and listen for idle to raise.

Were any problems found or did the idle fluctuate while tapping on the ETC Motor or IAC Motor?

Yes

- Repair or replace as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 5


5. 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. Powertrain Verification Test

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test