Buick Regal: 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

The throttle actuator control (TAC) motor is a DC motor that is part of the throttle body assembly. The TAC motor drives the throttle valve. The engine control module (ECM) controls the TAC motor based on throttle position sensor input. The idle speed is controlled by the ECM based on various inputs. The ECM commands the TAC motor to open or close the throttle valve in order to maintain the desired idle speed.

Conditions for Running the DTC

• DTCs P0068, P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0171, P0172, P0174, P0175, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268. P0270, P0271, P0273, P0274, P0276, P0277, P0300 - P0306, P0351 - P0356, P0461 - P0464, P0496, P0627, P0628, P0629, P0722, P1516, P2066 - P2068, are not set.
• The barometric pressure (BARO) is greater than 70 kPa.
• The engine coolant temperature (ECT) is greater than 60ºC (140ºF).
• The engine run time is greater than 60 s.
• The ignition voltage is between 11 - 32 V.
• The transmission is not changing gears.
• The torque converter clutch (TCC) is not changing states.
• The intake air temperature (IAT) is warmer than -20ºC (-4ºF).
• The vehicle speed is less than 3 km/h (2 mph).
• The commanded engine speed is steady within 25 RPM.
• The engine is idling for greater than 5 s.
• The DTCs run when the above conditions are met.

Conditions for Setting the DTC

P0506

The actual engine speed is 94 RPM less than the desired idle speed for 10 s.

P0507

The actual engine speed is 188 RPM greater than the desired idle speed for 10 s.

Action Taken When the DTC Sets

DTCs P0506 and P0507 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P0506 and P0507 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

Description and Operation

Throttle Actuator Control (TAC) System Description

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

1. Ignition ON.

2. Verify there are no other DTCs set.

• If any other DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

• Go to next step: If no other DTCs are set

3. Verify the scan tool Throttle Body Idle Airflow Compensation parameter is less than 90 %.

• If 90 % or greater

Refer to Throttle Body Cleaning.

• Go to next step: If less than 90 %

4. Engine Idling at the normal operating temperature.

5. Verify the actual Engine Speed is not 100 RPM less than the Desired Idle Speed.

• If 100 RPM less than the Desired Idle Speed

Refer to Circuit/System Testing.

• Go to next step: If 100 RPM greater than the Desired Idle Speed

6. Verify the actual Engine Speed is not 200 RPM greater than the Desired Idle Speed.

• If 200 RPM greater than the Desired Idle Speed

Refer to Circuit/System Testing.

• Go to next step: If 200 RPM less than the Desired Idle Speed

7. 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.

8. Verify the DTC does not set.

• If the DTC sets

Refer to Circuit/System Testing.

• Go to next step: If the DTC does not set

9. All OK

Circuit/System Testing

P0506

1. Verify the conditions listed below do not exist.
   • Restricted exhaust
   • Mechanical conditions that limits engine speed
   • Parasitic load on the engine - For example, a transmission condition, a belt driven accessory condition.
   • If a condition is found

     Repair as necessary.

   • Go to next step: If a condition is not found

2. All OK.

P0507

1. Verify the conditions listed below do not exist.

• Vacuum leaks
• A throttle valve that does not close correctly
• Verify the correct operation of the crankcase ventilation system. Inspect for the conditions listed below:
  • Improper routing of the positive crankcase ventilation (PCV) system
  • Vacuum leaks in the PCV system - Refer to Crankcase Ventilation System
• Inspection/Diagnosis.
• If a condition is found

Repair as necessary.

• Go to next step: If a condition is not found

2. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Throttle Body Assembly Replacement.

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