DTC P0506 Idle Speed Low. Chevrolet Alero Export 2000

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2000 🢒 Alero Export 🢒 Engine 🢒 Engine Controls - 2.4L 🢒 DTC P0506 Idle Speed Low

Engine Controls Components
Oil Pressure Sensor, IAC, PNP, and Generator
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Circuit Description

The Powertrain Control Module (PCM) controls the air entering into the engine with an idle air control (IAC) valve. 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 the throttle plate. To decrease the RPM, the PCM commands the pintle towards the throttle body seat. This reduces the amount of air bypassing the throttle plate. A scan tool will read the IAC valve pintle position in counts. The higher the counts, the greater the airflow bypassing the throttle plate.

Conditions for Running the DTC

•	The following DTCs are not set: P0105, P0107, P0108, P0117, P0118, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0201, P0202, P0203, P0204, P0300, P0325, P0335, P0341, P0342, P0440, P0442, P0446, P0452, P0453, P0480, P0481, P0502, P0503, P0601, P0602, P1133, P1441 and P1621.

•	The barometric pressure (BARO) is more than 72 kPa.

•	The engine coolant temperature (ECT) is more than 40°C (104°F).

•	The engine has been running for more than 20 seconds.

•	The throttle position (TP) angle is less than 1 percent.

Conditions for Setting the DTC

•	The engine RPM is less than the desired RPM by more than 100 RPM for 19 seconds.

•	The IAC command is more than 145 counts.

Action Taken When the DTC Sets

•	The malfunction indicator lamp (MIL) will illuminate after 2 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.

•	The coolant fan turns on.

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.

•	Use a scan tool to clear the DTCs.

Diagnostic Aids

•	Inspect the IAC valve electrical connection for proper mating.

•	Inspect the wiring harness for damage.

•	Inspect the throttle stop screw for signs of tampering.

•	Inspect the throttle linkage for signs of binding or excessive wear.

•	A slow or unstable idle may be caused by one of the following conditions:

-	A too-rich or a too-lean fuel system.

-	Any foreign material in the throttle body bore or in the air induction system.

-	A leaking or a restricted intake manifold.

-	An engine oil that is too thick in viscosity.

•	Refer to Rough, Unstable, or Incorrect Idle and Stalling in symptoms.

Test Description

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

The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.

DTC P0506 Idle Air Control (IAC) System Low RPM

Step

Action

Values

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Turn off all accessories.
With the parking brake set, and the transmission in Park or Neutral.
Start and idle the engine at the normal operating temperature.
With the scan tool command the RPMs up and down between the specified values.

Does the RPM change smoothly when commanded?

700-1500 RPM

Go to Diagnostic Aids

Go to Step 3

Turn off the ignition.
Disconnect the IAC valve connector.
Install a J 37027-A Node Lamp.
Turn on the ignition with the engine off, then turn off the ignition while observing the node lamp.

Does the node lamp cycle?

Go to Step 5

Go to Step 4

Test the IAC valve high and low circuits for the following conditions:

•

An open

•	A short to voltage

•	A short to ground

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

Did you find and correct the condition?

Go to Step 10

Go to Step 8

Inspect for the following conditions.

•	An obstructed or collapsed air intake duct, and a restricted air filter.

•	Any excessive deposits in the IAC passage or the throttle bore.

•	Any tampering of the throttle screw.

If a problem is found, repair as necessary.

Did you find and correct any of these conditions?

Go to Step 10

Go to Step 6

Inspect for poor connections at the IAC connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

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

Did you complete the repair?

Go to Step 10

Inspect for poor connections at the PCM connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 10

Use a scan tool to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK