Circuit Description
Diesel engines do not create enough engine vacuum on their own to allow the exhaust gas recirculation (EGR) gases into the combustion process. When the engine control module (ECM) commands the EGR valve to open, the EGR throttle valve will be commanded closed. The EGR throttle valve creates a restriction of incoming fresh air to the engine in order to create engine vacuum. When the EGR throttle valve is closed, engine vacuum develops and allows exhaust gases to enter the engine from the EGR system. The EGR throttle valve vacuum control solenoid is supplied 12 volts by the ignition 1 voltage circuit. The EGR throttle valve vacuum control solenoid is controlled through the EGR throttle valve vacuum solenoid control circuit by the ECM. If the ECM detects a high voltage condition on the EGR throttle valve vacuum solenoid control circuit, DTC P2142 sets.
Conditions for Running the DTC
| • | The ignition is ON for more than 0.5 seconds. |
| • | The EGR throttle valve vacuum control solenoid is commanded ON. |
| • | The Ignition 1 Signal parameter is between 11-18 volts. |
Conditions for Setting the DTC
| • | A high voltage condition on the control circuit of the EGR throttle valve vacuum control solenoid is detected by the ECM when the EGR throttle valve vacuum control solenoid is commanded ON. |
| • | The above conditions are met for more than 4 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. |
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 |
Does the tone of the engine change when the EGR throttle valve solenoid is commanded ON and OFF with a scan tool? | -- | Go to Step 3 | Go to Step 5 |
3 |
Does the current measure less than the specified value for the entire 2 minutes. | 0.75 A | Go to Step 4 | Go to Step 9 |
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions |
5 |
Does the test lamp turn ON and OFF when commanded with a scan tool? | -- | Go to Step 7 | Go to Step 6 |
6 | Test the Control circuit of the EGR throttle valve vacuum control solenoid for a short to voltage. Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 |
7 | Test for an intermittent and for a poor connection at the EGR throttle valve vacuum control solenoid. 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 11 | Go to Step 9 |
8 | Test for an intermittent and for a poor connection 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 11 | Go to Step 10 |
9 | Replace the EGR throttle valve vacuum control solenoid. Refer to Exhaust Gas Recirculation Vacuum Regulator Valve Solenoid Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Did the DTC fail this ignition? | -- | Go to Step 12 | Go to Step 2 |
12 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
