GM Service Manual Online
For 1990-2009 cars only

Object Number: 614824  Size: SF
Engine Controls Components
MAF Sensor, EVAP Canister Vent/Purge Solenoid Valve and EGR Valve
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

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 is turned ON, the PCM learns the EGR Closed Valve Pintle Position. The PCM compares the learned EGR closed valve pintle position to the Actual EGR position when the EGR valve is commanded closed. If the Actual EGR position 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

    • No TP, VSS, Misfire, IAT, MAP, Idle Speed, Fuel Injector, ECT, CKP, or MAF Sensor DTCs set.
    • System voltage is between 10-16 volts.

Conditions for Setting the DTC

    • EGR Feedback is 0.2 volt more than the EGR Closed Valve Pintle Position when the Desired EGR Position is commanded to 0 percent.
    • The above condition is present for longer than 20 seconds.

Action Taken When the DTC Sets

    • The PCM will illuminate the malfunction indicator lamp (MIL) during the first 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 and 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

Inspect for the following conditions:

    • 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.
    • Poor connections at PCM or EGR valve -- Inspect harness connectors for:
       - Backed out terminals
       -  Improper mating
       -  Broken locks
       -  Improperly formed or damaged terminals
       -  Poor terminal to wire connection
    • Damaged harness -- Inspect the wiring harness for damage. If the wiring appears to be OK, connect a DMM and check for 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.

Test Description

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

  1. This step verifies that the malfunction is present.

  2. If DTC P1404 will only set under certain conditions, the malfunction may be intermittent. Refer to DTC P1404 Diagnostic Aids. If an intermittent wiring problem is not present, inspect for a poor connection at the PCM or the EGR valve. If the connections are OK and DTC P1404 continues to set, replace the EGR valve. Refer to EGR Valve Replacement .

  3. 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.

DTC P1404 - EGR Valve Stuck Open

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important: If DTC P0403 is set, diagnose DTC P0403 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit first.

With the engine idling, observe Actual EGR Position on a scan tool.

Does the Actual EGR Position measure at the specified value?

0%

Go to Step 3

Go to Step 5

3

  1. Turn ON the ignition, with the engine OFF.
  2. Select the scan tool EGR valve output control function.
  3. Increment the EGR valve through all positions while comparing Desired EGR Position to Actual EGR Position.

Does Desired EGR Position remain close to Actual EGR Position at all commanded positions?

--

Go to Step 4

Go to Step 6

4

  1. Review and record scan tool Failure Records data.
  2. Operate the vehicle within the Failure Records conditions.
  3. Using a scan tool, monitor Specific DTC info for DTC P1404 until the DTC P1404 test runs.

Does the DTC reset?

--

Go to Step 5

Go to Diagnostic Aids

5

  1. Disconnect the EGR valve electrical connector.
  2. Observe Actual EGR Position on a scan tool.

Does the Actual EGR Position measure at the specified value?

0%

Go to Step 6

Go to Step 7

6

Probe the EGR pintle position sensor ground circuit at the EGR valve harness connector with a test lamp to B+.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 8

7

  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure voltage between the EGR valve pintle position signal circuit and ground.

Does the voltage measure near the specified value?

0 V

Go to Step 12

Go to Step 11

8

  1. Test the EGR pintle position sensor ground circuit for an open between the PCM and the EGR valve.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

9

  1. Inspect for poor terminal connections at the EGR valve.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 10

10

Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement .

Notice: In order to prevent further damage if the EGR valve shows signs of excessive heat, check the exhaust system for blockage (possibly a plugged converter) using the procedure found on the restricted exhaust system check. If the exhaust system is restricted, repair the cause; one of which might be an injector which is open due to one of the following reasons:

   • Stuck
   • Grounded driver circuit
Check the oil for possible fuel contamination if a stuck open fuel injector is found.

Did you find and correct the condition?

--

Go to Step 15

--

11

Locate and repair short to voltage in the EGR pintle position signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 15

--

12

  1. Test for the following conditions:
  2. • The EGR valve pintle position signal circuit for a short to the 5 Volt Reference circuit
    • The EGR valve pintle position signal circuit for a short to the EGR valve control circuit
  3. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

13

  1. Inspect the circuits related to the EGR valve for poor terminal connections at the PCM.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

14

Important:: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 15

--

15

  1. Use a scan tool to clear DTCs.
  2. Operate the vehicle within Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK