Circuit Description
This diagnostic test is used to determine if the idle control system is maintaining the proper idle speed. The IAC system controls idle speed by allowing a certain amount of air to bypass the throttle body, the throttle plate is closed during idle, through the IAC valve. The PCM controlled IAC motor moves a pintle in and out of the IAC valve, thus varying the amount of air entering the intake manifold. By varying the amount of air intake, different idle speeds can be achieved. When the pintle is in, the valve is closed and low idle speeds result. When the pintle is out, the valve is open and high idle speeds occur. If the engine idle speed is less than the desired idle speed and all the Conditions for Running the DTC are met then DTC P0506 will set.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0502, not set. |
| • | DTCs P1370, P1371, P1406 or, P1441 not testing. |
| • | PCM not checking EGR operation. |
| • | Ignition voltage between 10.5 and 15 volts. |
| • | BARO at least 65 kPa. |
| • | ECT is between -20°C (-4°F) and 110°C (230°F). |
| • | Engine running for at least 10 seconds. |
| • | PCM in Closed Loop fuel control. |
| • | MAF between 2 and 35 grams per second. |
| • | Actual idle speed less than desired idle speed by at least 80 RPM. |
| • | Throttle position 0.6 degrees or less. |
| • | Calculated throttle position switch closed. |
| • | Vehicle not moving. |
| • | A P/N to D/R or a D/R to P/N transition has not occured within the last 60 seconds. |
Conditions for Setting the DTC
Actual idle speed is more than 80 RPM lower than the desired idle speed for 15 seconds.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail. |
| • | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. |
| • | A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test. |
| • | Use a scan tool to clear DTCs. |
| • | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation. |
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
2 | Using a scan tool. Are any other DTCs set? | -- | Go to the appropriate DTC table | |||||||
3 |
Does the Engine Speed remain within the specified value of Desired Idle for each RPM command? | 50 RPM | Go to Diagnostic Aids | |||||||
4 |
Does each node light cycle red and green (never OFF)? | -- | ||||||||
5 |
Was a problem found and repaired? | -- | ||||||||
6 | Visually/physically inspect for the following conditions:
Do any of the above require a repair? | -- | Refer to appropriate section for on-vehicle service. | |||||||
7 | Check for poor terminal contact at the IAC harness connector. Was a problem found and repaired? | -- | ||||||||
8 | Replace the IAC valve. Is the repair complete? | -- | -- | |||||||
9 |
Was terminal contact repaired? | -- | ||||||||
10 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the repair complete? | -- | -- |
