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. The throttle position (TP) sensor and the ISC motor position sensor are also integrated into the throttle body assembly. Both of the position sensors share a common 5-volt reference circuit and a common low reference circuit. Each position sensor has an individual signal circuit, which provides the ECM with a signal voltage proportional to throttle plate movement. If the ECM detects the ISC motor position sensor signal voltage is too high, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0223 Idle Speed Control (ISC) Motor Position Sensor Circuit High Voltage
Conditions for Running the DTC
| • | The ignition is ON or the engine is operating. |
| • | The ignition 1 voltage is more than 10 volts. |
| • | This DTC runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the ISC position sensor voltage is more than 4.8 volts 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. |
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 the voltage more than the specified value? | 4.8 V | Go to Step 4 | Go to Step 3 |
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions . |
4 |
Is the voltage more than the specified value? | 5.2 V | Go to Step 7 | Go to Step 5 |
5 | Measure the signal circuit of the ISC motor position sensor to a good ground with a DMM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Is the voltage more than the specified value? | 0.5 V | Go to Step 8 | Go to Step 6 |
6 |
Is the resistance less than the specified value? | 3 ohms | Go to Step 10 | Go to Step 9 |
7 |
Important: The 5-volt reference circuits are internally connected within the controller. Other sensors that share the 5-volt reference circuit may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors. Test the 5 V reference circuit of the ISC motor position sensor for 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 |
8 | Test the signal circuit of the ISC motor position sensor 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 |
9 | Test the low reference circuit of the ISC motor position sensor for an open and for a high resistance. 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 | |
