Circuit Description
The powertrain control module (PCM) monitors the exhaust gas recirculation (EGR) valve pintle position input to ensure that the valve responds properly to commands from the PCM. When the ignition switch is turned on, the PCM learns the EGR closed valve pintle position. The PCM compares the learned EGR closed valve pintle position to the actual EGR position when the EGR valve is commanded closed. If the actual EGR position indicates that the EGR valve is still open when the PCM is commanding the EGR valve closed, DTC P1404 is set.
Conditions for Running the DTC
| • | None of the following DTCs are set: |
| • | Throttle position (TP) sensor DTCs |
| • | Vehicle speed sensor (VSS) DTCs |
| • | Intake air temperature (IAT) sensor DTCs |
| • | Manifold absolute pressure (MAP) sensor DTCs |
| • | Engine coolant temperature (ECT) sensor DTCs |
| • | Crankshaft position (CKP) sensor DTCs |
| • | Mass air flow (MAF) sensor DTCs |
| • | Misfire DTCs |
| • | Idle speed DTCs |
| • | Fuel injector DTCs |
| • | The system voltage is between 10 and 16 volts. |
Conditions for Setting the DTC
| • | The EGR feedback is 0.4 volt greater than the EGR closed valve pintle position when the Desired EGR Position is commanded to 0% |
| • | The above condition is present for longer than 20 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 has run and failed. |
| • | The PCM disables the EGR for the ignition cycle |
| • | The PCM stores the conditions which were present when the DTC set as Freeze Frame and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns the MIL off during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC may be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Inspect for the following conditions:
| • | Excessive deposits on the EGR valve pintle or seat. Remove the EGR valve and inspect for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick. |
| • | A faulty connections at the PCM or the EGR valve. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections. |
| • | Inspect the wiring harness for damage. If the wiring appears to be OK, connect a digital multimeter (DMM) and test the circuit continuity while moving the connectors and wiring harnesses related to the EGR valve. A change in the DMM display indicates the location of the malfunction. |
Test Description
The number(s) below refer to the step number(s) on the Diagnostic Table:
-
Verifies that the malfunction is present.
-
If DTC P1404 only sets under certain conditions, the malfunction may be intermitten. Refer to DTC P1404 Diagnostic Aids. If an intermittent wiring problem is not present, inspect for a faulty connection at the powertrain control module (PCM) or the EGR valve. If the connections are OK and DTC P1404 continues to set, replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement .
-
his vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
|
Important: If DTC P0403 is set, diagnose DTC P0403 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit first. With the engine idling, use a scan tool in order to observe the Actual EGR Position display. Is the Actual EGR Position at the specified value? | 0% | |||||||||
Does the Desired EGR Position remain close to the Actual EGR Position at all commanded positions? | -- | |||||||||
Does the scan tool indicate DTC P1404 Failed This Ign? | -- | Go to Diagnostic Aids | ||||||||
5 |
Is the Actual EGR Position at the specified value? | 0% | ||||||||
6 | Use a test lamp connected to B+ in order to probe the EGR pintle position sensor ground circuit at the EGR valve harness connector. Does the test lamp illuminate? | -- | ||||||||
7 |
Is the voltage near the specified value? | 0 V | ||||||||
8 |
Was a problem found? | -- | ||||||||
9 |
Was a problem found? | -- | ||||||||
10 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Notice: If the EGR valve shows signs of excessive heat, inspect the exhaust
system for blockage--possibly a plugged converter--using the procedure
found on the Restricted Exhaust System Check. If the exhaust system is restricted,
repair the cause. Inspect for an open injector caused by one or more of the
following conditions:
Did you complete the repair? | -- | -- | |||||||
11 | Locate and repair a short to voltage in the EGR pintle position signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||
12 |
Was a problem found? | -- | ||||||||
13 |
Was a problem found? | -- | ||||||||
|
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the repair? | -- | -- | ||||||||
15 |
Does the scan tool indicate DTC P1404 Failed This Ign? | -- | System OK |
