GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. This voltage varies depending on the position of the EGR valve. The ECM interprets this voltage as the position of the EGR valve. When the ignition switch is turned ON, the ECM records the minimum value of the EGR valve position sensor which is the learned closed position. If the ECM detects a difference between the actual closed EGR position and the learned closed position of the EGR valve, 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

    • The engine is operating.
    • The ignition 1 voltage is more 10 volts.
    • DTC P1404 runs continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects the voltage on the control circuit of the EGR valve is low while the valve is not commanded or high while the valve is being commanded.

Actions Taken When the DTC Sets

    • The malfunction indicator lamp (MIL) will illuminate after 3 consecutive trips with a fail.
    • The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.

Conditions for Clearing the MIL/DTC

    • The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault.
    • DTCs can be cleared by using the scan tool.
    • Disconnect the ECM battery feed for more than 10 seconds.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests for a high resistance in the 5-volt reference or low reference circuit of the EGR valve.

  2. This step tests for a high resistance in the signal circuit of the EGR valve.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Is DTC P0404, P0405, P0406, or P1403 also set?

 

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

  1. Turn ON the ignition, with the engine OFF.
  2. Observe the EGR Position Sensor parameter with a scan tool.

Is the voltage within the specified range?

0.60-0.80 V

Go to Step 4

Go to Step 5

4

  1. Observe the Freeze Frame/Failure Records data for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running the DTC.

Did the DTC fail this ignition?

--

Go to Step 5

Go to Intermittent Conditions

5

  1. Turn OFF the ignition.
  2. Disconnect the exhaust gas recirculation (EGR) valve.
  3. Turn ON the ignition, with the engine OFF.
  4. Important: Use a test lamp that measures between 25-30 ohms.

  5. Connect a test lamp between the 5-volt reference circuit and the low reference circuit of the EGR valve position sensor.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 6

6

Connect a test lamp between the 5-volt reference circuit of the EGR valve position sensor and a good ground.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 8

7

  1. Connect a 3-ampere fused jumper wire between the signal circuit and the low reference circuit of the EGR valve position sensor.
  2. Observe the EGR Position Sensor parameter on the scan tool.

Is the parameter less than the specified value?

0.05 V

Go to Step 11

Go to Step 10

8

Test the 5-volt reference circuit of the EGR valve position sensor 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 15

Go to Step 12

9

Test the low reference circuit of the EGR valve position sensor 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 15

Go to Step 12

10

Test the signal circuit of the EGR valve position sensor 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 15

Go to Step 12

11

Test the EGR valve for the following:

    • Excessive deposits on the EGR valve pintle that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.
    • An intermittent and poor connection at 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 15

Go to Step 13

12

Test for an intermittent and for a poor connection at the engine control module (ECM). 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 15

Go to Step 14

13

Replace the EGR valve.

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 16

16

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK