Circuit Description
The PCM monitors the 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 will set.
Conditions for Running the DTC
| • | No TP, IAT, MAP, ECT, CKP, or MAF sensor, VSS, Misfire, Idle Speed, Fuel Injector DTCs set. |
| • | IAT is greater than -10°C (14°F). |
| • | Engine run time is achieved. The length of time ranges from 20 seconds to 6 minutes depending upon engine coolant temperature at startup. |
| • | Throttle position is greater than 2%. |
| • | Vehicle speed is greater than 2 mph. |
| • | System voltage is between 10 volts and 16 volts. |
Conditions for Setting the DTC
| • | EGR Feedback is 0.2 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 will illuminate the MIL during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will disable EGR for the ignition cycle |
| • | The PCM will store conditions which were 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 during the third consecutive trip in which the diagnostic has been 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 the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Check for the following condition(s):
| • | Excessive deposits on the EGR valve pintle or 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 PCM or EGR valve. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
| Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
| • | Damaged harness. Refer to Wiring Repairs in Wiring Systems. |
| Inspect the wiring harness for damage. If the wiring appears to be OK, connect J 39200 DMM and check circuit continuity while moving connectors and wiring harnesses related to the EGR valve. A change in the DMM display will indicate the location of the malfunction. Refer to Wiring Repairs in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
Verifies that the malfunction is present.
-
If DTC P1404 will only set under certain conditions, the malfunction may be intermittent; refer to Diagnostic Aids. If an intermittent wiring problem is not present, check for a poor connection at the PCM or the EGR valve. If the connections are OK and DTC P1404 continues to set, replace the EGR valve.
-
This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain on Board Diagnostic (OBD) System Check performed? | -- | ||||||||
|
Important: : If DTC P0403 is set, diagnose DTC P0403 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit first. With the engine idling, observe Actual EGR Position display on the scan tool. Is Actual EGR Position at the specified value? | 0% | |||||||||
Does Desired EGR Position remain close to Actual EGR Position at all commanded positions? | -- | |||||||||
Does the scan tool indicate DTC P1404 failed this ignition? | -- | Go to Diagnostic Aids | ||||||||
5 |
Is Actual EGR Position at the specified value? | 0% | ||||||||
6 | Probe the EGR pintle position sensor ground circuit at the EGR valve harness connector with a test lamp to battery positive voltage. Does the test lamp illuminate? | -- | ||||||||
7 |
Is the measured voltage near the specified value? | 0.0V | ||||||||
8 |
Was a problem found? | -- | ||||||||
9 |
Was a problem found? | -- | ||||||||
10 | Replace the EGR valve. Refer to EGR 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:
Is the action complete? | -- | -- | |||||||
11 | Locate and repair short to voltage in the EGR pintle position signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||
12 |
Was a problem found? | -- | ||||||||
13 |
Was a problem found? | -- | ||||||||
|
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||||||||
15 |
Does the scan tool indicate DTC P1404 failed this ignition? | -- | System OK |
