Circuit Description
The powertrain control module (PCM) monitors the exhaust gas recirculation (EGR) valve pintle position input in order to ensure that the valve responds properly to the commands from the PCM. If 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 will set.
Conditions for Running the DTC
| • | The following DTCs did not set: |
| - | Throttle position (TP) sensor |
| - | Vehicle speed sensor (VSS) |
| - | Engine misfire |
| - | Intake air temperature (IAT) sensor |
| - | Manifold absolute pressure (MAP) sensor |
| - | Idle speed |
| - | Fuel injector |
| - | Engine coolant temperature (ECT) sensor |
| - | Crankshaft position (CKP) sensor |
| - | Mass air flow (MAF) sensor |
| • | The system voltage is between 10 volts and 16 volts. |
Conditions for Setting the DTC
| • | When you command the desired EGR position to 0 percent, the EGR feedback is 0.2 volt more than the EGR closed valve pintle position |
| • | The above condition is present for more than 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
Inspect for the following conditions:
| • | Excess deposits on the EGR valve pintle or on the seat--Remove the EGR valve and check for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick. |
| • | Poor connections at the PCM or at the EGR valve--Inspect the harness connectors for the following conditions: |
| - | Backed-out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly-formed terminals |
| - | Damaged terminals |
| - | Poor terminal-to-wire connections |
| • | A damaged harness--Inspect the wiring harness for damage. If the wiring appears OK, connect a DMM and check for circuit continuity while moving the connectors and the wiring harnesses that are related to the EGR valve. A change in the display will indicate the location of the malfunction. |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This step verifies that the malfunction is present.
-
If DTC P1404 will only set during certain conditions, the malfunction may be intermittent. Refer to DTC P1404 in Diagnostic Aids. If there is no intermittent wiring problem present, inspect for a poor connection at the PCM or at the EGR valve. If the connections are OK, and if DTC P1404 continues to set, replace the EGR valve. Refer to EGR Valve Replacement .
-
This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). When you replace the PCM, you must program the new PCM.
Step | Action | Values | 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, observe the actual EGR position on a scan tool. 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 DTC reset? | -- | Go to Diagnostic Aids | ||||||
5 |
Does the actual EGR position measure at the specified value? | 0% | ||||||
6 | Probe the EGR pintle position sensor ground circuit at the EGR valve harness connector with a test lamp connected to B+. Does the test lamp illuminate? | -- | ||||||
7 |
Is the voltage near the specified value? | 0V | ||||||
8 |
Did you find and correct the condition? | -- | ||||||
9 |
Did you find and correct the condition? | -- | ||||||
10 |
Notice: In order to prevent further damage if the EGR valve shows signs of excessive
heat, check 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; one of which might be an injector
which is open due to one of the following reasons:
Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you find and correct the condition? | -- | -- | |||||
11 | Locate and repair the short to voltage in the EGR pintle position signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||
12 |
Did you find and correct the condition? | -- | ||||||
13 |
Did you find and correct the condition? | -- | ||||||
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||||||
15 |
Does the DTC reset? | -- | System OK |
