Circuit Description
The engine control module (ECM) uses an exhaust gas recirculation (EGR) vacuum vent solenoid and an EGR valve vacuum control solenoid to control the position of the EGR valve. When the EGR valve is desired to open, the EGR vacuum vent solenoid is commanded open and the EGR valve vacuum control solenoid is commanded open. This will allow vacuum from the vacuum pump to open the EGR valve. When the EGR valve is desired closed, the EGR valve vacuum control solenoid is commanded closed and the EGR vacuum vent solenoid is commanded closed. When the EGR vacuum vent solenoid is commanded closed, the EGR vacuum control system is vented to atmosphere which causes the EGR valve to close very fast. The EGR vacuum vent solenoid is supplied 12 volts by the ignition 1 voltage circuit. The EGR vacuum vent solenoid is controlled through the EGR vacuum vent solenoid control circuit by the ECM. If the ECM detects a low voltage condition on the EGR vacuum vent solenoid control circuit, DTC P2144 sets.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The EGR vacuum vent solenoid is commanded OFF. |
| • | The Ignition 1 Signal parameter is between 11-18 volts. |
Conditions for Setting the DTC
A low voltage condition on the control circuit of the EGR vacuum vent solenoid is detected by the ECM when the EGR vacuum vent solenoid is commanded OFF.
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 | 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 EGR vacuum vent solenoid click with each command? | Go to Step 3 | Go to Step 4 |
3 |
Did the DTC fail this ignition? | Go to Step 4 | Go to Intermittent Conditions |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 6 |
5 |
Does the test lamp turn ON and OFF when command with a scan tool? | Go to Step 12 | Go to Step 7 |
6 | Inspect the Fuel HT fuse for an open. Is the fuse open? | Go to Step 11 | Go to Step 10 |
7 | Does the test lamp remain illuminated with each command? | Go to Step 9 | Go to Step 8 |
8 | Test the control circuit of the EGR vacuum vent solenoid for an open and for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 16 | Go to Step 13 |
9 | Test the control circuit of the EGR vacuum vent solenoid for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 16 | Go to Step 12 |
10 | Test the ignition 1 voltage circuit for an open or high resistance. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 16 | -- |
11 | Test the ignition 1 voltage circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 16 | Go to Step 12 |
12 | Test for an intermittent and for a poor connection at the EGR vacuum vent 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 16 | Go to Step 14 |
13 | 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 16 | Go to Step 15 |
14 | Replace the EGR vacuum vent solenoid. Refer to Exhaust Gas Recirculation Valve Vent Solenoid Replacement . Did you complete the replacement? | Go to Step 16 | -- |
15 | Replace the ECM. Refer to Engine Control Module Replacement Did you complete the replacement? | Go to Step 16 | -- |
16 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 17 |
17 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
