P1405

DTC P1405:

Digital EGR Solenoid Wiring Schematic:

CIRCUIT DESCRIPTION
Exhaust gas recirculation (EGR) is administered through a digitally controlled three solenoid valve unit. Each of the three valves is controlled individually and can be open or closed in any combination during a long closed throttle deceleration. The Powertrain Control Module (PCM) tests the EGR solenoids by momentarily commanding each solenoid "ON" while monitoring engine RPM. This test indicates if the EGR solenoids are operational electrically or if an EGR passage is obstructed. If the expected drop in RPM is not seen for a calibrated number of tests associated with solenoid #3 being commanded "ON." The PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon) and store DTC P1405.

DIAGNOSTIC TROUBLE CODE (DTC) P1405 WILL SET WHEN
^ Engine run time greater than 5 seconds.
^ Vehicle is in "Coast Down" condition.
^ Transmission not in 3rd or 4th gear.
^ Fuel control system is "Closed Loop" and Heated Oxygen Sensor (HO2S) voltage greater than 0.6 volt.
^ Vehicle not in decel fuel cutoff.
^ Engine coolant temperature is over 84°C (183°F).
^ Vehicle speed above 20 mph.
^ A/C clutch not engaged.
^ Engine RPM between 863 - 1113 for 0.07 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
EGR solenoid # 3 is tested by energizing the solenoid and checking the RPM drop. There should be a drop of 63 RPM within 0.6 seconds. Solenoid # 3 must fail 4 of 5 test to set the DTC P1405. Once 12 tests are run during and ignition cycle, the PCM will not run EGR solenoid test until the next ignition cycle. With a current DTC P1405 set. The PCM will illuminate the MIL (Service Engine Soon).

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test determines if there is power to the EGR valve.
2. This test will determine if there is an open circuit in the EGR wiring or if the EGR valve is at fault.
3. This test will determine if there is a short to ground in CKT 699 going to the EGR valve or if the PCM is at fault.

DIAGNOSTIC AIDS
An intermittent may be caused by a wire broken inside the insulation.

Check For:

Poor Connection or Damaged Harness
Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connections and damaged harness.

Intermittent Test
An intermittent may be caused by a poor connection, chaffed wire insulation, or a wire broken inside the insulation.

Intake plenum should be checked for possible plugged passages.

NOTICE:
If the EGR valve shows signs of excessive heat, check the exhaust system for blockage (possibly a plugged converter) using the procedure found on CHART B-1B Charts.

If the exhaust system is restricted, repair the cause; one of which might be an injector which is open due to one of the following:

A. Stuck.
B. Grounded driver circuit.
C. Possible faulty PCM.

If this condition is found, the oil should be checked for possible fuel contamination.