Refer to
PCM Emission Inputs
in Engine Controls Schematics .
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. The PCM compares Actual EGR Position with Desired EGR Position when the valve is commanded open. If Actual EGR Position is 15 percent less than Desired EGR position when the PCM is commanding the EGR valve opened, DTC P404 will set.
Conditions for Running the DTC
| • | The following sensor diagnostic trouble codes (DTCs) are not set: |
| - | Throttle position (TP) sensor |
| - | Mass air flow (MAF) sensor |
| - | Heated oxygen sensor (HO2S) |
| - | Intake air temperature (IAT) sensor |
| - | Engine coolant temperature (ECT) sensor |
| • | Engine run time met -- The time ranges from 45 seconds to 8.5 minutes depending upon engine coolant temperature at startup. |
| • | TP angle is more than 2 percent. |
| • | DTC P0401 diagnostic not running. |
| • | System voltage is more than 10 volts. |
Conditions for Setting the DTC
| • | Actual EGR Position and Desired EGR Position disagree by more than 20 percent. |
| • | The above conditions are present for longer than 10 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
The PCM will disable EGR for the rest of the ignition cycle.
Conditions for Clearing the MIL/DTC
| • | The PCM turns the MIL OFF after 3 consecutive drive trips during which the diagnostic runs and passes. |
| • | A last test failed, or the current DTC, clears when the diagnostic runs and passes. |
| • | A History DTC clears after 40 consecutive warm-up cycles, if no other emission related diagnostic failures are reported. |
| • | Use a scan tool in order to clear the MIL diagnostic trouble code. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description , Clearing Diagnostic Trouble Codes. |
Diagnostic Aids
Notice: Use the connector test adapter kit J 35616-A for any test that
requires probing the following items:
• The PCM harness connectors • The electrical center fuse/relay cavities • The component terminals • The component harness connector
Check for 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.
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs.
If the problem is intermittent, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step 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 problem is suspected, check for poor connections at the PCM or the EGR valve. If the wiring and connections are OK and DTC P0404 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 | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||
|
Important: If any of the following DTCs are set, refer to the applicable DTC table:
Does Desired EGR Position remain close to Actual EGR Position at all commanded positions? | -- | |||||||
3 | Does Actual EGR Position always indicate the specified value? | 100% | ||||||
4 | Disconnect the EGR valve. Does Actual EGR Position indicate the specified value? | 0% | ||||||
Does the scan tool indicate DTC P0404 failed this ignition? | -- | Go to Diagnostic Aids | ||||||
6 |
Is the voltage at the specified value? | 5V | ||||||
7 | Probe the EGR pintle position signal circuit at the EGR valve harness connector with a test lamp connected to B+. Is the test lamp ON? | -- | ||||||
8 |
Is the Actual EGR Position at the specified value? | 100% | ||||||
9 |
Was a problem found and corrected? | -- | ||||||
10 |
Is the test lamp ON? | -- | ||||||
11 |
Was a problem found and corrected? | -- | ||||||
12 |
Was a problem found and corrected? | -- | ||||||
13 |
Was a problem found and corrected? | -- | ||||||
14 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Is the action complete? | -- | -- | |||||
15 | Locate and correct the short to ground in the EGR pintle position signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | ||||||
16 |
Was a problem found and corrected? | -- | ||||||
17 |
Was a problem found and corrected? | -- | ||||||
18 |
Was a problem found and corrected? | -- | ||||||
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||||||
20 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||
21 | Review Captured Info using the scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
