Circuit Description
The throttle actuator control (TAC) motor is controlled by the engine control module (ECM). The DC motor located in the throttle body drives the throttle plate. In order to decrease idle speed, the ECM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the ECM commands the throttle plate open allowing more air to pass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0506 Idle Speed Low
Conditions for Running the DTC
| • | DTCs P0068, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0130, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0222, P0223, P0300, P0336, P0442, P0446, P0452, P0453, P0641, P0651, P1516, P2101, P2135, P2176 are not set. |
| • | The engine is operating for at least 40 seconds. |
| • | The engine coolant temperature (ECT) is between -40 and +110°C (-40 and +230°F). |
| • | The intake air temperature (IAT) is more than -18°C (+10°F). |
| • | The barometric pressure (BARO) is more than 70 kPa. |
| • | The system voltage is between 10.5-18 volts. |
| • | The engine is at idle for more than 2 seconds. |
| • | DTC P0506 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | The actual idle speed is approximately 100 RPM lower than the desired idle speed. |
| • | The above condition is present for 9 seconds. |
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. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | |||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |||||||||
Does the engine speed correspond within 100 RPM with each command? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 | |||||||||
3 | Inspect for any condition that can reduce idle speed by increasing engine load. Examples include:
Did you complete the action? | Go to Step 4 | -- | ||||||||
4 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 5 | ||||||||
5 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |||||||||
