For 1990-2009 cars

### 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. If the ECM detects the actual idle speed and the desired idle speed are not within a predetermined amount, this DTC sets.

### DTC Descriptors

This diagnostic procedure supports the following DTCs:

• | DTC P0506 Idle Speed Low

• | DTC P0507 Idle Speed High

• | DTC P050A Cold Start Idle Air Control (IAC) System Performance

### Conditions for Running the DTC

#### P0506 and P0507

• | Before the ECM can report DTC P0506 or P0507 failed, transmission DTCs P0722 and P0723 must run and pass.

• | DTCs P0111, P0112, P0113, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0221, P0222, P0223, P0442, P0443, P0446, P0455, P0458, P0459, P0496, P0722, and P0723 are not set.

• | Engine coolant temperature (ECT) is -10.5°C (+13°F).

• | The intake air temperature (IAT) is more than 10.5°C (+13°F).

• | The evaporative emission (EVAP) canister purge valve is OFF.

• | The engine coolant temperature (ECT) is greater than -10.5°C (+13°F).

• | In the deceleration condition, load is less than 2-35 percent.

• | The speed is at idle running condition.

• | The altitude is greater than the specified value.

• | The engine is ON.

• | Idle control is disabled on cold start.

• | Intrusive evaporative emissions test is inactive.

• | DTC P0506 and P0507 run continuously once the above conditions are met for more than 10 seconds.

#### P050A

• | DTCs P0111, P0112, P0113, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0221, P0222, P0223, P0442, P0443, P0446, P0455, P0458, P0459, P0496, P0722, and P0723 are not set.

• | On cold start, engine coolant temperature is between -10 to +40°C (+14 to +104°F).

• | The load is less than 35 percent only during deceleration.

• | The speed is at idle running condition.

• | The altitude is greater than the specified value.

• | The initiative engine coolant temperature is below 80°C (176°F)

• | The three-way catalytic converter is on heat status.

• | The evaporative emission (EVAP) canister purge valve is OFF.

• | The three-way catalytic converter heat idle control is enabled.

• | Intrusive evaporative emissions test is inactive.

• | The above conditions exist for more than 5 seconds, DTC P050A runs once at every ignition cycle.

### Conditions for Setting the DTC

#### P0506

The actual engine speed is less than the desired idle speed by at least 100 RPM for 4 seconds.

#### P0507

• | The actual engine speed is more than the desired idle speed by at least 200 RPM for 4 seconds.

| OR

• | The ECM detects 3 fuel cut-offs due to an engine over speed condition while the engine is idling.

#### P050A

• | When heating catalyst, the actual engine speed is less than the desired idle speed by at least 100 RPM or 200 RPM.

• | One of the above condition is present for 4 seconds.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 4 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.

### Diagnostic Aids

• | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.

• | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Front of Vehicle/Engine Compartment Component Views.

• | For an intermittent condition, refer to Intermittent Conditions.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. If any of the listed DTCs are present, correct the condition before returning to this table.

2. This test determines whether the engine can achieve the commanded RPM, and if not, whether the engine speed is too high or too low.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Component Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Are any throttle actuator control (TAC), throttle position (TP) sensor, or accelerator pedal position (APP) sensor DTCs set? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 3
3 |

1. Start the engine.
2. Command the engine speed up to 1,400 RPM, down to 600 RPM, up to 1,400 RPM, and then exit using the scan tool.

Is the actual engine speed within the specified value of the commanded engine speed, with each command?

100 RPM

Go to Step 4

Go to Step 5

4 |

1. Observe the Freeze Frame/Failure Records for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. 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.

Does the DTC fail this ignition?

--

Go to Step 5

Go to Intermittent Conditions

5 | Is the engine speed more than the specified value above the desired RPM? | 100 RPM | Go to Step 6 | Go to Step 7
6 |

1. Inspect or test for the following conditions:

• | The engine for vacuum leaks

• | The throttle valve for the correct operation - throttle valve that does not close correctly sets this DTC.

• | The crankcase ventilation system for the correct operation - Inspect for the following conditions:

- | The correct positive crankcase ventilation (PCV) valve is used.

- | The routing of the PCV system

- | Vacuum leaks in the PCV system

2. Repair the condition as necessary.

Did you complete the repairs?

--

Go to Step 8

--

7 |

1. Inspect for the following conditions:

• | Excessive deposits in the throttle body

• | A parasitic load on the engine - For example, a transmission condition, a belt driven accessory condition.

2. Repair the condition as necessary.

Did you complete the repairs?

--

Go to Step 8

--

8 |

1. Clear any DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. 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.

Does the DTC fail this ignition?

--

Go to Step 2

Go to Step 9

9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK