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 LowDTC P0507: Idle Speed High
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 P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0122, P0123, P0128, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0300, P0351, P0352, P0353, P0496, P0601, P0604, P0606, P060D, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, or P2176 are not set. |
| • | The engine has been running for greater than 60 seconds. |
| • | The engine is idling for greater than 10 seconds. |
| • | The intake air temperature (IAT) is more than -40°C (-40°F). |
| • | The AC mode state has not changed. |
| • | The barometric pressure (BARO) is greater than 72 kPa. |
| • | The power steering load state has not changed. |
| • | The transmission gear selector state has not changed. |
| • | The engine coolant temperature (ECT) is greater than -40°C (-40°F). |
| • | The system voltage is between 9-18 volts. |
| • | The vehicle speed is less than 4.8 km/h (3 mph). |
| • | The DTCs run continuously when the above conditions are met. |
Conditions for Setting the DTC
P0506
The ECM detects that the actual idle speed is approximately 100 RPM lower than the desired idle speed continuously.
P0507
The ECM detects that the actual idle speed is approximately 200 RPM higher than desired idle speed.
Action Taken When the DTC Sets
DTC P0506 and P0507 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTC 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
Connector End View Reference
Description and Operation
Throttle Actuator Control (TAC) System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Using a scan tool compare the desired engine idle speed to the actual engine idle speed.
- Verify that there are no other DTCs set.
- 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.
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.
| ⇒ | Actual engine idle speed should be no greater than 100 RPM below desired. |
| ⇒ | Actual engine idle speed should be no greater than 200 RPM above desired. |
| ⇒ | If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. |
Circuit/System Testing
- Inspect for any condition that can reduce idle speed by increasing engine load.
- Inspect for the following conditions:
| • | 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. |
| • | Vacuum leaks |
| • | A faulty positive crankcase ventilation (PCV) valve |
Repair Verification
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
