Circuit Description
The engine control module (ECM) adjusts the fuel delivery in order to control
crankshaft speed at idle. If the ECM detects the engine speed is incorrect for the
amount of fuel that is delivered, DTC P0506 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0506 Idle Speed Low
Conditions for Running the DTC
| • | DTCs P0016, P0117, P0118, P0335, P0336, P0340, P0341, P0500, or
P0700 are not set. |
| • | The engine is running at idle for more than 10 seconds. |
| • | The idle is stable to within 20 RPM. |
| • | Fuel delivery is less than 2.5 mm³ per cylinder of target
quantity. |
| • | The engine coolant temperature (ECT) is more than 50°C (122°F). |
| • | The intake air temperature (IAT) is less than 20°C (68°F). |
| • | The vehicle speed is 0 mph. |
| • | The throttle angle is 0 percent. |
Conditions for Setting the DTC
Actual idle speed is more than 100 RPM under the target idle speed.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp
(MIL) on the second consecutive ignition cycle that the diagnostic runs and
fails. |
| • | The control module records the operating conditions at the time
the diagnostic fails. The first time the diagnostic fails, the control module
stores this information in the Failure Records. If the diagnostic reports
a failure on the second consecutive ignition cycle, the control module
records the operating conditions at the time of the failure. The control
module writes the operating conditions to the Freeze Frame and updates
the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL)
after 3 consecutive ignition cycles that the diagnostic runs and does
not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs
and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles,
if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
