P0506

Refer to Engine Controls Schematics.

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

CIRCUIT DESCRIPTION
The PCM controls engine idle speed by adjusting the position of the Idle Air Control (IAC) motor pintle. The IAC is a bi-directional motor driven by two coils. The PCM applies current to the IAC coils in pulses (counts) to extend the IAC pintle into a passage in the throttle body to decrease air flow. The PCM reverses the current to retract the pintle, increasing air flow. This method allows highly accurate control of idle speed and quick response to changes in engine load. If the PCM detects a condition where too low of an idle speed is present and the PCM is unable to adjust idle speed by increasing the IAC counts, DTC P0506 will set indicating a problem with the idle control system.

CONDITIONS FOR RUNNING THE DTC
^ Active TP, ECT, MAP, AT, MAF, CKP, sensor, EVAP, misfire, EGR, VSS, Fuel Trim, injector circuit DTCs are not present.
^ ECT is above 70°C (158°F).
^ The engine has been running for at least 2 minutes.
^ System voltage is between 9.0-18.0 volts.
^ Vehicle speed is less than 3 mph.
^ IAT is above -18°C (5°F).
^ The throttle is less than 1.5 percent.
^ BARO above 65 kPa.

CONDITIONS FOR SETTING THE DTC
^ Engine speed is more than 100 RPM lower than desired idle.
^ The above condition is present for more than 15 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
^ The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
^ If the misfire is determined to be catalyst damaging, the PCM will flash the MIL.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
^ The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
Inspect for the following conditions:
^ Restricted air intake system-Inspect the air intake duct for being collapsed, foreign objects blocking the air intake system or a restricted air filter element.
^ Throttle body-Inspect for objects blocking the IAC passage or throttle bore, excessive deposits in the IAC passage and on the IAC pintle, and excessive deposits in the throttle bore and on the throttle plate.
^ Large vacuum leak-Inspect for a condition that causes a large vacuum leak, such as a incorrectly installed or faulty PCM valve or brake booster hose disconnected. Refer to Visual/Physical Inspection in Symptoms. Symptom Related Diagnostic Procedures

IMPORTANT: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

^ Poor terminal connection-Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension.
^ Damaged harness-Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault.
^ PCM and engine grounds for clean and secure connections

If the DTC is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set.

TEST DESCRIPTION
The number below refers to the step number on the diagnostic table:
10. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.