P1404

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
This diagnostic checks for a EGR valve that is stuck open. The PCM determines that the EGR valve is stuck open if the actual EGR position and the learned closed EGR position vary by more than a predetermined value. The PCM checks for a stuck valve when the desired EGR position is at 0%. The PCM commands the EGR valve to 100% during certain driving conditions in order to clear a possible restriction from the EGR valve if the PCM determines that the valve is stuck open. The PCM rechecks for a stuck valve when the desired EGR position returns to 0%. A failure timer increments if the stuck EGR valve condition is still present. This DTC sets when the timer reaches a predetermined value.

CONDITIONS FOR RUNNING THE DTC
The ignition voltage is greater than 11.7 volts.

CONDITIONS FOR SETTING THE DTC
The actual EGR pintle position is greater than 0.29 volts when the valve is commanded closed.

ACTION TAKEN WHEN THE DTC SETS
The PCM disables the EGR valve for the ignition cycle.

ACTION TAKEN WHEN THE DTC SETS
- The PCM illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
- The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM turns the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
- A last test failed (current DTC) clears when the diagnostic runs and does not fail.
- A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
- The PCM battery voltage is interrupted.
- Use a scan tool in order to clear the MIL/DTC.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. If DTC P1635 sets at the same time, this indicates that the 5.0 volt reference circuit is either shorted to a ground or shorted to a voltage. The 5.0 volt reference circuit is internally connected within the PCM.
3. This step checks for open EGR valve when the valve should be closed.
6. Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicated the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For an intermittent condition, refer to Symptoms. Testing and Inspection
5. This step checks for an EGR pintle position voltage that is out of range. The EGR pintle position voltage should be between 0.14 and 1.07 volts at idle.
8. This checks whether the ground circuit is available to the EGR valve. Check for poor electrical connections at the EGR valve. Refer to Repair Procedures in Electrical Diagnosis.