P0403

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

CIRCUIT DESCRIPTION
The PCM controls the movement of the valve using the EGR control circuit. The control circuit consists of a high side driver and feed circuit, the EGR solenoid, and a ground circuit. The PCM turns ON the high side driver to supply ignition voltage to the EGR control circuit. The PCM monitors the high side driver for improper voltage levels in the EGR control circuit. If the PCM detects an improper voltage in the EGR control circuit, DTC P0403 will set.

CONDITIONS FOR RUNNING THE DTC
^ The engine is running.
^ System voltage is between 8-16 volts.

CONDITIONS FOR SETTING THE DTC
The PCM detects an improper voltage in the EGR ignition feed, EGR solenoid, or EGR ground circuit for at least 10 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test runs and tails.
^ The PCM stores the conditions present when the DTC set as Freeze Frame and Fail Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the scan tool Clear DTC Information function.

DIAGNOSTIC AIDS
Check the harnesses and connectors for the following conditions:
^ Poor connections at the PCM and the EGR valve.
^ Backed out terminals
^ Improperly mated connectors
^ Broken locks
^ Improperly formed or damaged terminals
^ Poor terminal to wire connections
^ A damaged harness.

Refer to Wiring Repairs in Diagrams.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may assist in diagnosing the condition. The information may help in determining how often the condition occurs that caused the DTC to set.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the EGR valve can be commanded open.
3. Excessive resistance in the EGR control circuit or the EGR ground circuit will result in the EGR not responding correctly to the commanded EGR position.
4. This step tests the EGR Valve control circuit.
5. This step tests the EGR Valve ground circuit.
6. Excessive resistance in the control circuit or the ground circuit will cause this DTC to set. With the EGR commanded to 100 percent the test lamp should light with full intensity. Connect the test lamp across the battery terminals and compare the test lamp intensity to the EGR control circuit intensity.