For 1990-2009 cars

### 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 Descriptor

DTC P0506 00: Idle Speed Low
DTC P0507 00: 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 P0107 00, P0108 00, P0117 00, P0118 00, P0120 00, P0122 00, P0123 00, P0128 00, P0171 00, P0172 00, P0201 00, P0202 00, P0203 00, P0204 00, P0222 00, P0223 00, P0300 00, P0496 00, P0601 00, P0604 00, P0606 00, P061A 00, P0641 00, P2101 00, P2119 00, P2122 00, P2123 00, P2127 00, P2128 00, P2138 00, or P2176 00 are not set.

• | The engine has been running for greater than 60 s.

• | The engine is idling for greater than 10 s.

• | The intake air temperature (IAT) is more than -40°C (-40°F).

• | The transmission gear selector state has not changed.

• | The engine coolant temperature (ECT) is greater than 50°C (122°F).

• | The system voltage is between 9-18 V.

• | The vehicle speed is less than 4.8 km/h (3 mph).

• | DTCs P0506 00 or P0507 00 run continuously when the above conditions are met.

### Conditions for Setting the DTC

#### P0506 00

• | The ECM detects that the actual idle speed is continuously approximately 100 RPM lower than the desired idle speed.

• | The above condition is present for 15 s.

#### P0507 00

• | The ECM detects that the actual idle speed is approximately 200 RPM higher than desired idle speed.

• | The above condition is present for 15 s.

### Action Taken When the DTC Sets

DTC P0506 00 and P0507 00 are Type B DTCs.

### Conditions for Clearing the DTC

DTC P0506 00 and P0507 00 are Type B DTCs.

### Diagnostic Aids

• | A stalling condition can cause DTC P0506 00 to set.

• | An intermittent vehicle speed sensor (VSS) signal can cause DTC P0507 00 to set.

• | An intermittent clutch pedal position sensor signal, if equipped, can cause DTC P0506 00 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

Note: 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. Using a scan tool compare the desired idle speed to the actual engine speed.

⇒ | Actual engine speed should be no greater than 100 RPM below desired.

⇒ | Actual engine speed should be no greater than 200 RPM above desired.

2. Verify that there are no other DTCs set.

⇒ | 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. Inspect for any condition that can reduce idle speed by increasing engine load.

• | Incorrect torque converter clutch (TCC) operation

• | Accessories that require additional torque to operate

• | Excessive deposits in the Q38 Throttle Body

• | Restricted exhaust

• | Mechanical conditions that limit engine speed

⇒ | Repair any conditions, if necessary.

2. Inspect for the following conditions:

• | Vacuum leaks

• | A faulty positive crankcase ventilation valve

⇒ | Repair any conditions, if necessary.

### Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Throttle Body Inspection and Cleaning