DTC P0506 Idle Speed Low. Chevrolet PJJ 2000

For 1990-2009 cars
Engine Controls Components
IAC Valve, Generator, TR and Coolant Switches
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

### Circuit Description

The 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 of the IAC valve away from the throttle body seat. This allows more air to bypass through the throttle blade. 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 greater the airflow that bypasses the throttle blade.

### Conditions for Running the DTC

• | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0201, P0202, P0203, P0204P0335, P0341, P0342, P0440, P0442, P0446, P0480, P0502, P0503, P0601, P0602, P1133, and P1441 not set

• | The BARO is more than 72 kPa.

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

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

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

### Conditions for Setting the DTC

• | The engine RPM is below 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 two consecutive ignition cycles in which the diagnostic runs with the malfunction present.

• | The PCM records the operating conditions present at the time the diagnostic fails. This information stores 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 three 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 fuel system that is too rich or too lean

- | Foreign material in the throttle body bore or in the air induction system

- | A leaking or restricted intake manifold

- | An excessive engine load -- Check for seized pulleys, pumps, or motors on the accessory drive.

- | Overweight engine oil

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

### Test Description

The number below refers to the step number on the diagnostic table:

1. This vehicle is equipped with a PCM that utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Are any other DTCs set? | -- | Go to Diagnostic Trouble Code (DTC) List/Type | Go to Step 3

3

1. Start the engine.
2. Turn all accessories off (A/C, Rear defroster etc.).
3. Using a scan tool, command the 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 Desired Idle range for each RPM command?

±50 RPM

Go to Diagnostic Aids

Go to Step 4

4

1. Disconnect the IAC.
2. Install a J 37027-A IAC Node Lamp or equivalent.
3. 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 6

Go to Step 5

5

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

• | The IAC A low circuit

• | The IAC A high circuit

• | IAC B low circuit

• | The IAC B high circuit

2. 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

6

Visually and physically inspect for the following conditions:

• | Throttle body tampering -- Observe whether the throttle lever stop screw has been turned.

• | A restricted air intake system -- Inspect for a possible collapsed air intake duct, restricted air filter element, or foreign objects blocking the air intake system.

• | Remove the IAC Valve. Refer to Idle Air Control Valve Replacement .

• | Inspect for objects blocking the IAC passage or throttle bore. Look for excessive deposits in the IAC passage and on the IAC pintle, and excessive deposits in the throttle bore and on the throttle plate. If a problem is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 7

7

1. Inspect for a faulty connection at the IAC harness connector.
2. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections .

Did you find and correct the condition?

--

Go to Step 11

Go to Step 8

8 | Replace IAC valve. Refer to Idle Air Control Valve Replacement . Did you complete the replacement? | -- | Go to Step 11 | --

9

1. Inspect for a faulty connection at the PCM harness connector.
2. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections .

Did you find and correct the condition?

--

Go to Step 11

Go to Step 10

10 | Important: : 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 11 | --

11

1. Reinstall and connect components as necessary.
2. Start the engine.
3. Turn all of the accessories off (A/C, Rear defroster etc.).
4. Using a scan tool, command the RPM up to 1500, down to 650, and then up to 1500 while monitoring Engine Speed on the scan tool.

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

±50 RPM

System OK

Go to Step 2