Circuit Description
The throttle body assembly contains an idle speed control (ISC) motor that is used to control the engine speed at idle. The engine control module (ECM) commands the ISC motor to adjust the throttle angle for idle speed control. An idle switch is also integrated into the throttle body assembly. The idle switch position is dependant upon the position of the throttle. The ECM receives an ON signal from the idle switch when the throttle is at idle and receives an OFF signal from the switch when the throttle is open . If the ECM detects a fault with the idle switch, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0510 Idle Position Switch Circuit
Conditions for Running the DTC
| • | The ignition is ON, with the engine OFF. |
| • | The throttle is closed. |
Or
| • | The engine is running. |
| • | The throttle is more than 35 degrees. |
| • | This DTC runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the idle switch signal is OFF when the throttle is less than 10 degrees for more than 2 seconds.
Or
The ECM detects that the idle switch signal is ON when the throttle is more than 35 degrees for more than 1 second.
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. |
-
This step verifies the condition. The scan tool should display ON with a closed throttle and OFF with an open throttle.
-
This step tests for the correct operation of the idle switch within the throttle body . The idle switch is a normally closed switch and the test lamp should illuminate with a closed throttle. The test lamp should go OFF when the throttle is opened.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connect End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |
2 |
Is DTC P0122, P0123, P0222 or P0223 also set? | -- | Go to Step 3 | |
Observe the idle switch parameter with a scan tool while slowly depressing the accelerator pedal to wide open throttle. Does the idle switch parameter change when the accelerator pedal is depressed? | -- | Go to Step 4 | Go to Step 5 | |
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 10 | |
6 | Slowly open the throttle to wide open throttle. Does the test lamp remain illuminated? | -- | Go to Step 10 | Go to Step 7 |
7 |
Is the voltage more than the specified value? | 11 V | Go to Step 9 | Go to Step 8 |
8 | Test the idle switch signal circuit for an open or for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
9 |
Important: The throttle body assembly or the engine control module (ECM) may be damaged if the circuit is shorted to a voltage source. Test the idle switch signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 |
10 | Test for shorted terminals and for poor connections at the throttle body. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 |
11 | Test for shorted terminals and for poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 |
12 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
13 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- |
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 |
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
