P0506

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

CIRCUIT DESCRIPTION
The control module controls idle speed with an Idle Air Control (IAC) valve. The desired RPM is based on sensor inputs and the actual engine RPM. Four circuits are used in order to control the IAC valve, allowing a precise amount of air into the intake manifold.

In order to increase the idle RPM, the control module will command the valve pintle to move away from its seat, allowing more air to bypass the throttle plate. To decrease RPM, the control module commands the IAC pintle to move closer to its seat, causing a lower airflow to bypass the throttle plate. A scan tool will display the control module commands to the IAC valve in counts. The higher the counts, the more air is allowed to bypass the throttle plate. Lower counts indicate that less air is commanded by the control module.

CONDITIONS FOR RUNNING THE DTC

Test Enable: (non-intrusive)
^ No active Throttle Position (TP) sensor DTCs
^ No active Vehicle Speed Sensor (VSS) DTCs
^ No active Engine Coolant Temperature (ECT) sensor DTCs
^ No active Manifold Absolute Pressure (MAP) sensor DTCs
^ The ECT is more than 50°C (122°F)
^ The system voltage is 10-16 volts
^ The IAT is more than 25°C (-13°F)
^ The engine has been running for more than 30 seconds
^ The Barometric Pressure (BARO) is more than 70 kPa
^ Any change in the throttle position is less than 1 percent
^ The vehicle speed is less than 1 km/h (2 mph)
^ The above conditions are present for more than 3 seconds
^ If the non-intrusive test fails, the intrusive test is run

Run Test: (intrusive)
^ The Mass Air Flow (MAF) is between 17.5-50 g/s
^ Any change in the engine speed is less than 50 RPM
^ The vehicle speed is 40 - 136 km/h (25 - 85 mph)
^ Any change in throttle position is less than 1 percent
^ The Idle Air Control (IAC) valve was commanded to move a specified number of counts

CONDITIONS FOR SETTING THE DTC
The change in MAF is less than 3 g/s

ACTION TAKEN WHEN THE DTC
^ The control module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
^ The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame and Failure Records.

CONDITIONS FOR CLEARING THE MIL OR DTC
^ The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
^ Use a scan tool in order to clear the DTCs.

DIAGNOSTIC AIDS
The following items could cause this DTC:
^ A stuck IAC valve cannot respond to the VCM
^ A throttle stop screw which has been tampered with
^ A damaged throttle shaft, plate, or linkage

A slow, unstable, or fast idle may be caused by a non-IAC valve system problem that cannot be overcome by the IAC valve. Out of range control IAC scan tool counts will read more than 60 if the idle is too low and zero if the idle is too high. Check for the following:
^ The fuel system too lean or rich
^ Inspect the throttle body and the bore for foreign material.
^ Any vacuum leaks
^ Refer to Symptoms. Symptom Related Diagnostic Procedures
^ An IAC reset is done with the scan tool.

An intermittent may be caused by any of the following conditions:
^ A poor connection
^ Rubbed through wire insulation
^ A broken wire inside the insulation

Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections in Diagrams.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Diagrams.

TEST DESCRIPTION
The numbers below refer to the numbers in the diagnostic table.
5. The IAC Reset function used in this step only energizes the circuit for 2 seconds so this function will have to be used repeatedly during this step. It is recommended that the connector test adapter kit is used during this procedure to prevent terminal damage to the IAC harness connector. This step can also be performed with the ignition ON and the engine OFF.
6. If the test lamp remains ON at any of the IAC valve harness connector terminals during the IAC valve reset function the circuit is shorted to voltage. If these circuits are checked before or after the IAC valve reset function it is possible that any combination of IAC circuits could light a test lamp. This would be a normal condition.