P0506

Diagnostic Chart 1 Of 2:

Diagnostic Chart 2 Of 2:

Schematic:

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 sends pulses (steps) to the IAC to extend or retract the IAC pintle into a passage in the throttle body to decrease or increase air flow. The commanded IAC position (displayed in counts) can be monitored on the scan tool; a higher number of counts indicates more commanded airflow (pintle retracted). 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
There are no VSS, EVAP, TP sensor, misfire, IAT sensor, MAP sensor, fuel trim, fuel injector, EGR, ECT sensor, CKP sensor, or MAF sensor DTCs set.
^ The vehicle speed is less than 3 MPH.
^ The engine has been running for at least 2 minutes.
^ The system voltage is between 9-18 volts.
^ The BARO is more than 65 kPa.

The engine coolant temperature is more than -40°C (-40°F).
^ The Intake air temperature is more than -40°C (-40°F).
^ The throttle position is below 25 percent.

CONDITIONS FOR SETTING THE DTC
^ The engine speed is more than 150 RPM lower than Desired Idle (negative idle speed error more than 150 RPM).
^ The above conditions are present for longer than 15 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the MIL during the second consecutive trip in which the diagnostic test runs and fails.
^ The PCM stores the conditions that were present when the DTC set as Freeze Frame and Fail Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns the MIL OFF during the third consecutive trip in which the diagnostic runs and passes.
^ The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

DIAGNOSTIC AIDS
Check for the following conditions:
^ A poor connection at the PCM or the idle air control (IAC) motor.
Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Use a corresponding mating terminal to test for proper terminal tension.
^ A damaged harness.
Inspect the wiring harness for damage.
^ A restricted air intake system
Check for a possible collapsed air intake duct, restricted air filter element, or foreign objects blocking the air intake system.
^ The throttle body
Check 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.
^ A large vacuum leak.
Check for a condition that causes a large vacuum leak, such as a incorrectly installed or malfunctioning crankcase ventilation valve or brake booster hose disconnected.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs that caused the DTC to set. This may assist in diagnosing the condition.

TEST DESCRIPTION
Numbers below refer to the step numbers 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.