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 learned minimum position. The PCM compares the EGR learned minimum position to the EGR position sensor when the EGR valve is commanded closed. If the EGR position sensor 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 system voltage greater than 11.6 volts. |
| • | The EGR is enabled. |
| • | After an initial test failure a 30 percent valve opening must be achieved and maintained for at least 5 seconds. |
Conditions for Setting the DTC
| • | The EGR position sensor is 0.4 volt more than the EGR learned minimum position when the Desired EGR Position is commanded to 0 percent. |
| • | The above condition is present 4 times. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
Inspect for the following condition:
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.
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.
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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, test for a faulty connection at the PCM or the EGR valve. If the connections are OK and DTC P1404 continues to set, replace the EGR valve.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
|
Important: If a DTC P0403 is set diagnose that DTC first.
Does the scan tool indicate that the EGR position sensor is at the specified value? | 0% | Go to Step 3 | Go to Step 5 | |
3 |
Does the Desired EGR Position remain close to the EGR position sensor at all commanded positions? | -- | Go to Step 4 | Go to Step 6 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids | |
5 |
Does the scan tool indicate that the EGR position sensor is at the specified value? | 0% | Go to Step 6 | Go to Step 9 |
6 | Measure the voltage from the 5-volt reference circuit of the EGR position sensor to the low reference circuit of the EGR position sensor. Does the DMM display voltage near the specified value? | 5 V | Go to Step 7 | Go to Step 8 |
7 |
Important: : If the fuse blows, locate and repair a short to ground in the signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Connect a fused jumper between the 5-volt reference circuit of the EGR position sensor and the EGR valve position signal circuit of the EGR position sensor. Does the scan tool indicate that the EGR position sensor is near the specified value? | 100% | Go to Step 13 | Go to Step 11 |
8 | Measure the voltage from the 5-volt reference circuit of the EGR position sensor to a good ground. Does the DMM display voltage near the specified value? | 5 V | Go to Step 10 | Go to Step 12 |
9 | Test the EGR valve position signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
10 | Test the EGR position sensor low reference circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
11 | Test the signal circuit for high resistance or a high resistance short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 |
12 |
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 |
13 | Inspect for poor connections at the harness connector of the EGR valve. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 |
14 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 |
15 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Pipe Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
16 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
17 |
Does the DTC run and pass? | -- | Go to Step 18 | Go to Step 2 |
18 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
