GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Tahoe - 4WD 🢒 Engine 🢒 Engine Controls and Fuel - Hybrid (HP2) 6.0L (LFA) 🢒 DTC P0506 or P0507

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0506: Idle Speed Low

DTC P0507:  Idle Speed High

Circuit/System Description

This vehicle does not use a 12V starter motor to crank the internal combustion engine. A much more powerful 300V drive motor generator can rotate the engine to operating speed, 800 RPM, within just a few hundred milliseconds. During an engine cranking event, the HPCM can detect a condition where the engine is cranking but does not start.

Conditions for Running the DTC

    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0122, P0123, P0171, P0172, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0221, P0222, P0223, P0230, P0300, P0336, P0442, P0446, P0449, P0452, P0453, P0455, P0462, P0463, P0496, P0722, P077B, P0A3F, P0A40, P0A45, P0A46, P0C5C, P0C5D, P0C52, P0C53, P0C57, P0C58, P0C61, P0C62, P1516, P2101, P2135, P2176, P1B03, P1B04, P215C are not set.
    • The engine is operating for at least 60 seconds.
    • The engine is idling for greater than 5 seconds.
    • The engine coolant temperature (ECT) is more than -60°C (-76°F).
    • The intake air temperature (IAT) is more than -20°C (-4°F).
    • The barometric pressure (BARO) is more than 70 kPa.
    • The system voltage is between 9-18 volts.
    • The vehicle speed is less than 1.6 km/h (1 mph).
    • DTC P0506 and P0507 run continuously once the above conditions are met.

Conditions for Setting the DTC

P0506

The actual idle speed is approximately 75 RPM lower than the desired idle speed.

P0507

The actual idle speed is approximately 150 RPM greater than the desired idle speed.

Action Taken When the DTC Sets

DTCs P0506 and P0507 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0506 and P0507 are Type B DTCs.

Diagnostic Aids
    • A stalling condition can cause DTC P0506 to set.
    • An intermittent vehicle speed sensor (VSS) signal can cause DTC P0507 to set.
    • An intermittent clutch pedal position sensor signal, if equipped, can cause DTC P0506 to set.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Important: The engine must first be running for greater than 60 seconds, then idle at a steady state for an additional 10 seconds before comparing the actual and desired engine idle speed parameters.

  1. Use a scan tool to compare the desired engine idle speed to the actual engine idle speed.
    2. ⇒Actual engine idle speed should be no greater than 75 RPM below desired.
    ⇒Actual engine idle speed should be no greater than 150 RPM above desired.
  2. If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing
  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description.
  2. Ignition ON, verify the scan tool hood position parameter displays OPEN.
    3. ⇒If the hood position does not display OPEN, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
  3. Inspect for any condition that can reduce idle speed by increasing engine load.
    4. • 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.
  4. Inspect for the following conditions:
    5. • Vacuum leaks
    • A faulty positive crankcase ventilation (PCV) valve

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.