Circuit Description
The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM. The PCM compares Actual EGR Position with Desired EGR Position when the valve is commanded open. If Actual EGR Position is 15% less than Desired EGR position when the PCM is commanding the EGR valve opened, DTC P404 will set.
Conditions for Running the DTC
| • | System Voltage is between 10 volts and 16 volts. |
| • | EGR is enabled. |
Conditions for Setting the DTC
| • | Actual EGR position is 15% less than Desired EGR Position. |
| • | The above conditions are present for longer than 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive 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/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
Check for the following condition(s):
| • | Excessive deposits on the EGR 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 connection at PCM or EGR Valve. |
| Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. |
| Inspect the wiring harness for damage. If the harness 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 display will indicate the location of the malfunction. |
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
-
Verifies that the malfunction is present.
-
If DTC P0404 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 P0404 continues to set, replace the EGR valve.
-
Tests for voltage on the 5 volt reference circuit and continuity of the sensor ground.
-
Tests the pintle position signal circuit for a short to ground.
-
Tests for continuity on both the 5 volt reference and the pintle position signal circuits.
-
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 | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
|
Important: If any of the following DTCs are set, diagnose the other DTC first.
Does Desired EGR Position remain close to Actual EGR Position at all commanded positions? | -- | |||
Does the scan tool indicate DTC P0404 failed this ignition? | -- | Go to Diagnostic Aids | ||
4 |
| 5V | ||
5 | Probe the EGR pintle position signal circuit with a J 35616-200 test lamp that is connected to B+. Does the test lamp illuminate? | -- | ||
6 |
Is Actual EGR Position at the specified value? | 100% | ||
7 | Test the EGR pintle position signal circuit for an open. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
8 | Test the 5 volt reference circuit and the sensor ground circuit for an open. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
9 | Inspect for poor connections at the EGR valve. Refer to Intermittents and Poor Connections Diagnosis . Did you find and correct the condition? | -- | ||
10 | Test the pintle position signal circuit for a short to ground or a short sensor ground. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
11 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you complete the replacement? | -- | -- | |
12 |
Did you find and correct the condition? | -- | ||
|
Important: Perform the set up procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the replacement complete? | -- | -- | ||
14 |
Does the DTC reset? | -- | System OK |
