Circuit Description
The linear EGR system consists of a linear EGR valve, the PCM, and its associated
wiring. The EGR valve solenoid is controlled directly by the PCM when certain conditions
have been met. The PCM contains a diode feedback circuit which dissipates energy when
the valve is cycled OFF. When the PCM commands the EGR valve closed, a closed valve
position value is learned. If the PCM commands the valve closed and the actual feedback
value does not match the learned values, DTC P1404 will set.
Conditions for Setting the DTC
Important: When the PCM recognizes that the parameters
for setting DTC P1404 have been set, the diagnostic software waits until the
EGR cycles open 50 percent or greater 4 times and then resets. If after
the 3 cycles the actual vs learned is not within the parameters,
the DTC will be stored and the MIL, service engine soon, will be commanded ON.
Important: When this DTC sets, functions will be disabled.
When repairs are complete, codes must be cleared and the ignition keyed OFF for at
least 10 seconds to allow proper operation.
DTC P1404 will set when the actual closed value does not match the learned closed
value within 20 seconds if:
| • | RPM is below 5,000 and the actual vs learned is greater
than 0.2 volts. |
| • | RPM is above 5,000 and the actual vs learned is greater
than 0.4 volts. |
Diagnostic Aids
| • | Check for backed out or damaged terminals. |
| • | Check for a stuck open EGR pintle. Inspect the EGR pintle valve bore for
carbon or debris and remove. Verify that the pintle moves freely and the return spring
forces the pintle closed. |
| • | An open in circuit 452 will result in DTC P1404. |
| • | A short to ground is circuit 697 will result in a severe rough
idle and driveability complaint and set a DTC P1404. |
| • | Compare the learned closed pintle position to the actual closed pintle
position with the key ON and the engine OFF. If voltage differs more than 0.15 volts,
check for backed out, damaged, poor terminal tightness, or an intermittent open in
circuits 416 or 1456. |
