Circuit Description
The engine control module (ECM) uses the exhaust gas recirculation (EGR) position sensor to determine the position of the EGR valve. The ECM sends a reference voltage through the 5-volt reference circuit to the EGR position sensor. The ECM provides a voltage return path for the sensor through the low reference circuit. A variable voltage signal, based on the EGR valve position, is sent from the sensor to the ECM through the EGR position sensor signal circuit. The ECM compares the actual EGR position with the desired EGR position when the EGR valve is commanded open or closed. If the ECM detects a difference between the learned closed position and the commanded closed position for a calibrated amount of time, DTC P1404 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1404 Exhaust Gas Recirculation (EGR) Closed Position Performance
Conditions for Running the DTC
| • | DTCs P0642 and P0643 are not set. |
| • | The ignition is ON for more than 0.5 seconds. |
| • | The ignition voltage is between 11-18 volts. |
| • | The intake air temperature (IAT) is between 0-150.75°C (32-303.35°F). |
| • | The engine coolant temperature (ECT) is between 57-99.75°C (134.6-211.6°F). |
| • | The barometric pressure (BARO) is more than 72 kPa. |
| • | The power take off (PTO) is not engaged. |
| • | The EGR has been commanded to more than 35 percent. |
| • | The current desired EGR position is 0 percent. |
| • | DTC P1404 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The actual EGR position is 0.8 volts, 6 percent, more than the learned closed position when the EGR valve is commanded closed, or the EGR learned minimum position is more than 1.25 volts. |
| • | The above condition is present for more than 5 seconds. |
Action Taken When the DTC Sets - California
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Action Taken When the DTC Sets - Federal
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The 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 (DIC), 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. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views and Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Important: Attaching the shop exhaust system to the vehicle may cause false exhaust gas recirculation (EGR) DTCs to set. Does the EGR Position parameter read more than the specified value? | 1.25 V | Go to Step 4 | Go to Step 3 |
3 |
Did the DTC fail this ignition cycle? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 | Is DTC P0403, P0405, or P0406 also set? | -- | Go to Step 5 | |
5 | Test for shorted terminals and poor connections at the exhaust gas recirculation (EGR) valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 6 |
6 |
Is the calculated resistance more than the specified value? | 5 ohms | Go to Step 7 | Go to Step 9 |
7 | Test for shorted terminals and poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 |
8 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
9 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 |
10 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 12 | -- |
12 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 |
13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
