P1404

DTC P1404

Circuit Description
The exhaust gas recirculation (EGR) valve moves via the EGR valve motor and the EGR valve motor is controlled by the engine control module (ECM). The EGR valve position sensor is installed on the EGR valve body together with the EGR valve control motor. The EGR valve position sensor changes output voltage according to EGR valve position. The EGR valve has the following circuits.
- EGR valve motor 12 volts feed circuit
- EGR valve motor duty signal circuit
- EGR valve position sensor 5 volts reference circuit
- EGR valve position sensor low reference circuit
- EGR valve position sensor signal circuit

The ECM supplies 5 volts to the EGR valve position sensor on the 5 volts reference circuit. The ECM also provides a ground on the low reference circuit. The EGR valve position sensor provides a signal to the ECM on the EGR valve position signal circuit which is relative to the position changes of the EGR valve. The ECM monitors the EGR position sensor signals for voltage outside the normal range of the EGR position. If the ECM detects EGR valve position signal voltage too high (indicating an open valve) when the EGR valve is commanded closed, this DTC will set.

Condition for Running the DTC
- The battery voltage is between 10-16 volts.
- The ignition switch is ON.
- The EGR valve is being commanded closed.

Condition for Setting the DTC
- The ECM detects that the EGR position is more than 45%.

Action Taken When the DTC Sets
- The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
- The ECM limits fuel injection quantity within 50%.
- The ECM closes the EGR valve and stops EGR control.
- The ECM inhibits cruise control.

Condition for Clearing the DTC
- A current DTC clears when the ignition is turned OFF..
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
A sticking EGR valve may set this DTC.
If an intermittent condition is suspected, the following may cause an intermittent:
- Poor connections.
- Misrouted harness.
- Rubbed through wire insulation.
- Broken wire inside the insulation.

Check for the following conditions:
- Poor connection at ECM: Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the EGR Position Sensor display on the scan tool while moving connectors and wiring harness related to the sensor. A change in the display will indicate the location of the fault.

DTC P1404

Schematic Reference: Engine Controls Schematics