P0507

DTC P0507 Idle Control System High RPM




Circuit Description
The PCM controls the air entering into the engine with an Idle Control (IAC) valve. In order to increase the idle rpm, the PCM commands the pintle inside the IAC valve away from the throttle Body seat. This allows more air to bypass through the throttle blade. In order to decrease the rpm the PCM commands the pintle towards the throttle Body seat. This reduces the amount of air bypassing the throttle blade. A scan tool will read the IAC valve pintle position in counts. The higher the counts, the more air that is allowed to bypass the throttle blade.

Conditions for Running the DTC
- DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0200, P0335, P0341, P0342, P0440, P0442, P0446, P0480, P0502, P0503, P0601, P0602, P1133, and P1441 not set
- BARO is greater than 72 kPa.
- Engine Coolant Temperature (ECT) is greater than 40 °C (104 °F).
- Engine has been running more than 20 seconds.
- Throttle Position (TP) angle is less than 1%.

Conditions for Setting the DTC
- The idle speed deviates above desired rpm by greater than 60 RPM for greater than 5 seconds.
- The IAC valve reads less than 2 counts on the scan tool.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the malfunction present.
- The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.
- A history DTC stores.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault
- A history DTC will clear after 40 consecutive warm up cycles without a fault
- A scan tool can clear the DTCs

Diagnostic Aids
Inspect the IAC valve electrical connection for proper mating.
- Inspect the wiring harness for damage.
- Inspect for a disconnected, cracked or cut vacuum hoses.
- Inspect for the proper installation of the crankcase ventilation valve.
- Inspect the intake manifold and throttle Body for leaks.
- Inspect the intake manifold for cracks.
- Refer to Rough, Unstable, or Incorrect Idle, Stalling.

Steps 1 - 3:

Steps 4 - 7:

Steps 8 - 12:

Steps 13 - 16:

Test Description
The number(s) below refer(s) to the step number(s) on the Diagnostic Table.
1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data for later reference.
2. A normally operating IAC system will be able to extend and retract by a scan tool and change the engine idle RPM. The valve movement is verified by an engine RPM change.
3. If the scan tool was able to command the IAC valve smoothly, a malfunction may still exist internally within the IAC valve. You can verify this by checking the internal resistance of the IAC valve.
5. The IAC circuits always have ground or voltage signals in pairs. If the test light illuminates on more or less than 2 terminals, one of the circuits is shorted to voltage or open.
6. The IAC circuits always have ground or voltage signals in pairs. If the test light illuminates on more or less than 2 terminals, one of the circuits is shorted to ground or open.
8. The IAC circuits are constantly switched between ground and voltage. The test light should blink on all circuits when connected to ground.
10. Thoroughly check any suspected circuitry for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminal to wiring connections
- Physical damage to the wiring harness.

12. A test light that remains ON constantly indicates that the circuit is shorted to voltage.
14. Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Isuzu Technical Communications system (ITCS) information for PCM programming and CKP System Variation Learn Procedure for the crankshaft position system variation learn procedure.
16. If no malfunctions are present at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.