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 Speed Control (ISC) Motor Position Sensor Circuit Low Voltage
Conditions for Running the DTC
| • | DTCs P0122, P0123, P0222, and P0223 are not set. |
| • | The ignition is ON, with the engine OFF. |
| • | The throttle is closed. |
| • | This DTC runs continuously once the above conditions are met. |
Or
| • | DTCs P0122, P0123, P0222, and P0223 are not set. |
| • | 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 0.2 seconds.
Action Taken When the DTC Sets - European Emissions
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
| • | A history DTC is stored. |
| • | The coolant fan turns ON. |
Action Taken When the DTC Sets - Non European Emissions
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The coolant fan turns ON. |
Conditions for Clearing the MIL/DTC - European Emissions
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for 10 seconds. |
Conditions for Clearing the MIL/DTC - Non European Emissions
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for 10 seconds. |
Test Description
The numbers below refer to the step numbers in the diagnostic table.
-
This step checks for a skewed throttle position (TP) sensor. High resistance in the TP sensor circuit can cause this DTC to set.
-
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 Connector 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 | |
Is the TP sensor percentage less than the specified value? | 8 % | Go to Step 4 | Go to DTC P0122 | |
4 | 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 5 | Go to Step 6 |
5 |
Did the DTC fail this ignition? | -- | Go to Step 6 | Go to Intermittent Conditions |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 11 | |
7 | Slowly open the throttle to wide open throttle. Does the test lamp remain illuminated? | -- | Go to Step 11 | Go to Step 8 |
8 |
Is the voltage more than the specified value? | 11 V | Go to Step 10 | Go to Step 9 |
9 | 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 15 | Go to Step 12 |
10 |
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 15 | Go to Step 12 |
11 | 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 15 | Go to Step 13 |
12 | Test for shorted terminals and for poor connections at the 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 15 | Go to Step 14 |
13 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
14 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
15 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 16 |
16 | Are there any DTCs that have not been diagnosed? | -- | System OK | |
