Circuit Description
The powertrain control module (PCM) controls the engine idle speed by adjusting the position of the idle air control (IAC) motor pintle. The IAC is a bi-directional motor driven by 2 coils. The PCM applies current to the IAC coils in pulses to extend the IAC pintle into a passage in the throttle body and decrease the air flow. The PCM reverses the current to retract the pintle, increasing the air flow. This method allows highly accurate control of the idle speed and a quick response to changes in the engine load. If the PCM detects a condition where too high an idle speed is present, and the PCM is unable to adjust the idle speed by decreasing the IAC counts, DTC P0507 will set.
Conditions for Running the DTC
| • | No active TP, ECT, MAP, IAT, MAF, CKP, EVAP, misfire, EGR, VSS, fuel trim, or injector circuit DTCs are active. |
| • | The ECT is more than 70°C (158°F). |
| • | The engine has been running for at least 2 minutes. |
| • | The system voltage is between 9.0-18.0 volts. |
| • | The vehicle speed is less than 4.8 km/h (3 mph). |
| • | The IAT is more than -18°C (0°F). |
| • | The throttle angle is less than 1.5 percent. |
| • | The barometric pressure (BARO) is more than 65 kPa. |
Conditions for Setting the DTC
| • | The IAC valve indicates less than 15 counts on the scan tool. |
| • | The engine speed is more than 175 RPM higher than the Desired Idle. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
Inspect for the following conditions:
| • | A poor connection at the PCM or IAC valve. Inspect harness connectors for the following conditions. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems: |
| - | Backed-out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal-to-wire connections |
| • | A damaged harness. Inspect the wiring harness for damage. Refer to Wiring Repairs in Wiring Systems. |
| • | A restricted air intake system. Inspect for a collapsed air intake duct, a restricted air filter element, or any foreign objects blocking the air intake system. |
| • | The throttle body. Inspect for objects blocking the IAC passage or the throttle bore, excessive deposits in the IAC passage, on the IAC pintle, in the throttle bore, and on the throttle plate. |
| • | A large vacuum leak. Inspect for a condition that causes a large vacuum leak, such as an incorrectly installed or faulty PCV valve or the brake booster hose disconnected. Refer to Symptoms . |
If the DTC cannot be duplicated and is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set. Also refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||
2 | Are any other DTCs set? | -- | Go to the applicable DTC table | |||||||||
3 |
Does the engine speed remain within the specified range of the Desired Idle for each RPM commanded? | ±50 RPM | Go to Diagnostic Aids | |||||||||
4 |
Does the node lamp cycle from red to green but never off? | -- | ||||||||||
5 |
Did you find and correct the condition? | -- | ||||||||||
6 |
Did you find and correct any conditions? | -- | Go to appropriate section for on vehicle service | |||||||||
7 |
Did you find and correct the condition? | -- | ||||||||||
8 | Replace the IAC valve. Refer to Idle Air Control Valve Replacement . Did you complete the replacement? | -- | -- | |||||||||
9 |
Did you find and correct the condition? | -- | ||||||||||
|
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||||||||||
11 |
Does the engine speed remain within the specified range of the Desired Idle for each RPM commanded? | ±50 RPM | System OK |
