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.
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 |
• | 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. |
• | 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. |
The actual engine speed is less than the desired idle speed by at least 100 RPM for 4 seconds.
• | 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. |
• | 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. |
• | 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. |
• | 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. |
• | 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 Engine Controls Component Views . |
• | For an intermittent condition, refer to Intermittent Conditions . |
The numbers below refer to the step numbers on the diagnostic table.
If any of the listed DTCs are present, correct the condition before returning to this table.
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: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||||
Are any throttle actuator control (TAC), throttle position (TP) sensor, or accelerator pedal position (APP) sensor DTCs set? | -- | Go to Step 3 | ||||||||||||||
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 |
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 |
Did you complete the repairs? | -- | Go to Step 8 | -- | ||||||||||||
7 |
Did you complete the repairs? | -- | Go to Step 8 | -- | ||||||||||||
8 |
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? | -- | System OK |