Spark

DTC P0511

The engine control module (ECM) controls the engine idle speed by adjusting the position of the idle air control (IAC) valve pintle. The IAC valve is a stepper motor driven by 2 internal coils. The movement of the IAC valve is controlled electrically by 4 circuits. Drivers within the ECM control the polarity of the 2 windings inside the IAC valve through these circuits. The ECM, by commanding the correct polarity in sequence, is able to command the motor within the IAC valve to rotate clockwise or anticlockwise in steps. In order for the armature of the stepper motor of the IAC valve to turn one revolution, it needs to move approximately 24 steps. The IAC valve motor is linked by a gear drive to the IAC valve pintle. The electrical pulses sent to the IAC valve coils, by the ECM, allows the pintle to extend or retract into the passage in the throttle body. By retracting the pintle, air is allowed to bypass the throttle valve, which will increase air flow and raise engine speed. When the pintle is extended, bypass air is decreased which lowers engine speed. IAC valve movement is measured in counts on the scan tool. Each count is equivalent to a step of the IAC valve. When the IAC valve is fully extended, and seated in the throttle body bore, the scan tool displays zero and the engine speed is slow. As the IAC valve pintle retracts the counts will raise along with engine speed.

The IAC valve utilises the following circuits:

The ECM detects a short circuit to battery, a short circuit to ground, or an open circuit on the idle air control (IAC) valve control circuit.

DTC P0511 is a Type E DTC.

DTC P0511 is a Type E DTC.

If the IAC valve is removed for any reason, perform the idle learn procedure to complete the repair or replacement.

Schematic Reference

Engine Controls Schematics : Siemens ECM - LPG with LCP → Siemens ECM - Gas without FX3 or LCP → Delphi ECM - FX3

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information.

1. Allow the engine to idle within the Conditions For Running the DTCs for 1 minute. DTC P0511 should not set.
2. Operate the vehicle within the Conditions For Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the IAC valve.
2. Connect a test lamp between the IAC coil A high control circuit terminal D and ground.

Note: This test must be performed on all of the IAC control circuits.

3. Ignition ON with engine OFF, verify the test lamp flashes while increasing or decreasing several steps of the IAC valve with a scan tool.

•	IAC A High Control terminal D

•	IAC A Low Control terminal C

•	IAC B High Control terminal B

•	IAC B Low Control terminal A

⇒	If the test lamp does not illuminate, test the applicable IAC control circuit for a short circuit to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒	If the test lamp illuminates but does not flash, test the applicable IAC control circuit for a short circuit to voltage. If the circuit tests normal, replace the ECM.

4. If all conditions test normal, test or replace the IAC valve.

1. Ignition OFF, disconnect the harness connector at the IAC valve.
2. Test for 40-80 Ω between the following terminals of the IAC valve:

•

A and B

•

C and D

⇒	If not within the specified range, replace the IAC valve.

3. Test for infinite resistance between the following terminals of the IAC valve:

•

A and C

•

A and D

•

B and C

•

B and D

⇒	If not the specified range, replace the IAC valve.

4. Test for infinite resistance between each terminal and the IAC valve housing.

⇒	If not the specified range, replace the IAC valve.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.