GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Impala 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC P0506 or P0507

DTC Descriptors

DTC P0506: Idle Speed Low

DTC P0507:  Idle Speed High

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description

The throttle actuator control (TAC) motor is controlled by the engine control module (ECM). The DC motor located in the throttle body drives the throttle blade. In order to decrease idle speed, along with spark and fuel delivery changes the ECM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the ECM commands the throttle plate open allowing more air to pass the throttle plate.

Conditions for Running the DTC
    • DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0122, P0123, P0128, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0300, P0443, P0502-if applicable, P0503-if applicable, P1174, P1175, or P2135, is not set.
    • The engine is idling for more than 1 second.
    • The engine coolant temperature (ECT) is more than -40°C (-40°F).
    • The intake air temperature (IAT) is more than -40°C (-40°F).
    • The barometric pressure (BARO) is more than 72 kPa.
    • The system voltage is between 9-18 volts.
    • The vehicle speed is less than 4.8 km/h (3 mph).
    • DTC P0506 and P0507 run continuously when the above conditions are met.

Conditions for Setting the DTC

P0506

    • The ECM detects that the actual idle speed is approximately 150 RPM lower than the desired idle speed continuously.
    •  The above condition is present for 3 tests consisting of 8 seconds each test.

P0507

    • The ECM detects that the actual idle speed is approximately 150 RPM higher than desired idle speed.
    • The above conditions is present for 3 tests consisting of 8 seconds each.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
    • The control module commands the TAC system to operate in the Reduced Engine Power mode.
    • A message center or an indicator displays Reduced Engine Power.
    • Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Controls Connector End Views
    •  Engine Control Module Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification
    • Using a scan tool compare the desired engine idle speed to the actual engine idle speed.
       ⇒Actual engine idle speed should be no greater than 100 RPM below desired.
       ⇒Actual engine idle speed should be no greater than 150 RPM above desired.

Circuit/System Testing
  1. Observe the DTC information on the scan tool.
    2. ⇒If there are any other DTCs set diagnose those first.
  2. Inspect for any condition that can reduce idle speed by increasing engine load.
    3. • Incorrect torque converter clutch (TCC) operation
    • Accessories that require additional torque to operate
    • Excessive deposits in the throttle body
    • Restricted exhaust
    • Mechanical conditions that limit engine speed
         ⇒Repair any conditions, if necessary.
  3. Inspect for the following conditions:
    4. • Vacuum leaks
    • A faulty positive crankcase ventilation (PCV) valve
         ⇒Repair any conditions, if necessary.

Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.