P0506

DTC P0506 Idle Air Control Counts Low:

Idle Air Control:

CIRCUIT DESCRIPTION
The Idle Air Control (IAC) valve is a stepper motor located in the throttle body that enables the Vehicle Control Module-A (VCM-A) to control idle speed under various conditions. To increase idle speed, the VCM-A will retract the IAC pintle away from its seat, allowing more air to bypass the throttle blades. To decrease idle speed, the VCM-A will extend the pintle towards its seat thereby reducing the air flow around the throttle blades. A Tech 1 will read the VCM-A commands to the IAC valve in counts. If the counts are high, the VCM-A is commanding a higher idle. If the counts are low, the VCM-A is commanding a lower idle. If the passive test fails and the active test passes, DTC P0506 will set. DTC P0506 is a type "B" DTC.

DTC P0506 WILL SET WHEN
Passive Test
^ No Throttle Position (TP) sensor DTC's set.
^ No Engine Coolant Temperature (ECT) DTC's set.
^ No Vehicle Speed Sensor (VSS) DTC's set.
^ No Manifold Absolute Pressure (MAP) DTC's set.
^ ECT is greater than 72°C (161.6°F).
^ Intake Air Temperature (IAT) is greater than -25°C (-13°F).
^ Commanded IAC is greater than 93 counts.
^ Barometric Absolute Pressure (BARO) is greater than 70 kPa (21 Hg).
^ Vehicle speed is less than 2 mph.
^ System voltage is between 10 volts and 18 volts.
^ Engine run time is greater than 30 seconds.
^ TP is less than 1%.
^ Engine speed is at least 75 RPM below desired engine speed.
^ Above met for a time greater than 3 seconds.

If the passive test fails, the active test is run
^ Commanded IAC is between 36 counts to 116 counts.
^ Calculated air flow is between 17.5 grams per second and 37.5 grams per second.
^ Vehicle speed is between 35 mph and 85 mph.
^ Change in TP sensor is less than 1%.
^ Change in engine speed is less than 30 RPM.
^ IAC motor commanded to 0 counts.
^ Change in calculated air flow is greater than 2 grams per second.
If the passive test fails and the active test passes DTC P0508 will set.

ACTION TAKEN (VCM-A WILL DEFAULT TO)
The VCM-A will turn "ON" the Malfunction Indicator Lamp (MIL) (Service Engine Soon) after 2 consecutive driving cycles with the fault active.

DTC P0506 WILL CLEAR WHEN
The VCM-A will turn the MIL "OFF" after three consecutive trips without a fault condition present. A history DTC will be cleared if no fault conditions have been detected for forty warm-up cycles [coolant temperature has risen 22°C (40°F) from start-up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle] or the Tech 1 clearing feature has been used.

DTC CHART TEST DESCRIPTION
1. This step makes sure no other DTC(s) are set.
2. This step refers to mechanical repair.

DIAGNOSTIC AIDS
An IAC valve which is stopped and cannot respond to the VCM-A, a throttle stop screw which has been tampered with, or a damaged throttle or linkage could cause a DTC P0506. 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 be above 60 if idle is too low and zero if idle is too high.
Check for the following:
^ Fuel system too lean and rich.
^ Throttle body - inspect bore for foreign material.
^ Refer to Rough, Unstable, Incorrect Idle or Stalling. Rough, Unstable, or Incorrect Idle, Stalling
^ IAC reset is done with Tech 1 scan tool misc functions mode.