DTC P0507 Idle Speed High. Chevrolet Monte Carlo 1999

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1999 🢒 Monte Carlo 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P0507 Idle Speed High

OBD II Symbol Description Notice
Engine Controls Components
Cell 21: Engine Data Sensors-IAC, Engine Oil Level
Handling ESD Sensitive Parts Notice

Circuit Description

The PCM controls engine idle speed by adjusting the position of the Idle Air Control (IAC) motor pintle. The IAC is a bi-directional motor driven by two coils. The PCM sends pulses (steps) to the IAC to extend or retract the IAC pintle into a passage in the throttle body to decrease or increase air flow. The commanded IAC position (displayed in counts) can be monitored on the scan tool; a lower number of counts indicates less commanded airflow (pintle extended). This method allows highly accurate control of idle speed and quick response to changes in engine load. If the PCM detects a condition where too high of an idle speed is present and the PCM is unable to adjust idle speed by decreasing the IAC counts, DTC P0507 will set indicating a problem with the idle control system.

Conditions for Running the DTC

•	No VSS, TP sensor, EVAP system, misfire, IAT sensor, MAP sensor, fuel trim, fuel injector, EGR pintle position, ECT sensor, CKP sensor, or MAF sensor DTCs set.

•	BARO is greater than 65 kPa.

•	Engine has been running for at least 2 minutes.

•	System voltage is between 9 and 16 volts.

•	Engine Coolant Temperature is greater than 70°C (158°F).

•	Vehicle Speed is less than 3 MPH.

•	Intake Air Temperature is greater than -18°C (0°F).

•	The throttle is closed.

Conditions for Setting the DTC

•	Engine Speed is more than 175 RPM higher than Desired Idle (positive idle speed error greater than 175 RPM).

•	Above conditions for longer than 15 seconds.

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

Check for the following conditions:

•	Poor connection at PCM or IAC motor. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

•	Damaged harness. Inspect the wiring harness for damage.

•	Vacuum leak. Check for a condition that causes a vacuum leak, such as disconnected or damaged hoses, leaks at EGR valve and EGR pipe to intake manifold, leaks at throttle body, malfunctioning or incorrectly installed PCV valve, leaks at intake manifold, etc.

•	Throttle body. Check for a sticking throttle plate. Also inspect the IAC passage for deposits or objects which will not allow the IAC pintle to fully extend.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Test Description

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

Before replacing the PCM, check the terminals for improper mating, broken locks, or physical damage to the wiring harness.

Step

Action

Value(s)

Yes

Was A Powertrain on-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Are any other DTCs set?

Got to applicable DTC

Go to Step 3

Start the engine.
Turn all accessories off.
Using a scan tool, command RPM up to 1500, down to 650, and then up to 1500 while monitoring the Engine Speed on the scan tool.

Does Engine Speed remain within the specified value of Desired Idle for each RPM commanded

50 RPM

Go to Diagnostic Aids

Go to Step 4

Disconnect the IAC.
Install IAC Node lamp J 37027 or equivalent.
With engine running, command RPM up to 1500, down to 650, and then up to 1500 while observing the node lamp.

Does the node lamp cycle from red to green (never off)?

Go to Step 6

Go to Step 5

Test the following circuits for an open, short to voltage, or a short to ground:

•

IAC A Low

•	IAC A High

•

IAC B Low

•	IAC B High

If a problem is found, repair as necessary. Refer to Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 9

Visually/Physically inspect for the following conditions:

•	Vacuum leaks

•	Throttle body tampering (Throttle Lever Stop Screw turned)

•	Throttle plate or throttle shaft for binding.

•	Faulty, missing, for incorrectly installed PCV Valve

Did you find and correct the condition?

Go to appropriate section for on vehicle service

Go to Step 7

Test for poor connection at the IAC harness connector.
if a problem is found repair as necessary. Refer to Intermittents and Poor Connections Diagnosis .

Did you find and correct the condition?

Go to Step 11

Go to Step 8

Replace the IAC Valve. Refer to Idle Air Control Valve Replacement .

Did you complete the replacement?

Go to Step 11

Test for poor connection at the PCM harness connector.
if a problem is found repair as necessary. Refer to Intermittents and Poor Connections Diagnosis .

Did you find and correct the condition?

Go to Step 11

Go to Step 10

Important: : Replacement PCM must be programmed.

Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Did you complete the replacement?

Go to Step 11

Start the engine.
Turn all the accessories off.
Using a scan tool, command RPM up to 1500, down to 650, and then up to 1500 while monitoring the Engine Speed on the scan tool.

Does the Engine Speed remain within the specified value of Desired Idle for each RPM commanded

50 RPM

System OK

Go to Step 2