GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2003 🢒 L300/LW300 🢒 DTC 🢒 DTC P1406

Object Number: 896244 Size: MF

Circuit Description

The exhaust gas recirculation (EGR) valve position sensor is monitored by the engine control module (ECM). The 5-volt reference circuit, low reference circuit and the EGR valve position signal circuit are used by the ECM to determine the EGR valve position. If the difference between the actual EGR valve position and the ECM desired EGR valve position is more than 20 percent, DTC P1406 sets.

Conditions for Running the DTC
    • The engine is running.
    • The ignition voltage is between 7.5-15 volts.

Conditions for Setting the DTC
    • The difference between the EGR valve position and the ECM desired EGR valve position is more than 20 percent.
    • The above condition is met for more than 10 seconds.

Action Taken When the DTC Sets
    • 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.

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 Controls Connector End Views or Engine Control Module 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

Important: The exhaust gas recirculation (EGR) valve pintle may not move until more than 40 percent duty cycle is applied.

  1. Turn ON the ignition, with the engine OFF.
  2. Command the EGR duty cycle to 100 percent while observing the EGR Sensor parameter with a scan tool.

Is the EGR Sensor parameter between the specified values when commanded with a scan tool?

4- 4.82 V

Go to Step 3

Go to Step 5

3

Command the EGR duty cycle to 0 percent while observing the EGR Sensor parameter with a scan tool.

Is the EGR Sensor parameter between the specified values?

0.14-1 V

Go to Step 4

Go to Step 5

4
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 90 seconds.
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 5

Go to Intermittent Conditions

5
  1. Command the EGR duty cycle to 100 percent with a scan tool.
  2. Observe the EGR Sensor parameter while wiggling the EGR connector.

Does the EGR Sensor parameter change?

--

Go to Step 17

Go to Step 6

6

Notice: Refer to Test Probe Notice in the Preface section.

  1. Exit the EGR control function on the scan tool.
  2. Disconnect the EGR valve.
  3. Measure the voltage from the 5-volt reference circuit of the EGR position sensor, at the harness connector, to a good ground with a DMM.
  4. Note this value as "supply voltage".
  5. Connect a test lamp and a DMM in series between the 5-volt reference circuit of the EGR position sensor , at the harness connector, and the low reference circuit of the EGR position sensor, at the harness connector.
  6. Measure the amperage and note as "current flow".
  7. Remove the DMM and connect the test lamp between the 5-volt reference circuit of the EGR position sensor , at the harness connector, and the low reference circuit of the EGR position sensor, at the harness connector.
  8. Connect a DMM in parallel between the 5-volt reference circuit of the EGR position sensor and a good ground.
  9. Measure the voltage and note as "load voltage drop".
  10. Subtract the load voltage drop from the supply voltage and divide your answer by the current flow in order to calculate the resistance in the 5-volt reference circuit.

Is the calculated resistance more than the specified value?

200 ohms

Go to Step 11

Go to Step 7

7
  1. With the test lamp still connected, connect a DMM in parallel between the low reference circuit of the EGR position sensor and a good ground.
  2. Measure and note the "low reference voltage drop".
  3. Divide the low reference voltage drop by the current draw in order to calculate the resistance in the low reference circuit

Is the calculated resistance more than the specified value?

5 ohms

Go to Step 12

Go to Step 8

8
  1. Remove the test lamp and the DMM.
  2. Connect a jumper wire between the 5-volt reference circuit and the signal circuit of the EGR position sensor, at the harness connector.
  3. Turn ON the ignition with the engine OFF.
  4. Observe the EGR Sensor parameter with a scan tool.

Is the voltage more than the specified value?

4.82 V

Go to Step 9

Go to Step 13

9
  1. Remove the jumper wire.
  2. Connect a DMM between the ignition positive voltage circuit of the EGR valve, at the harness connector, and a good ground.
  3. Measure the voltage and note as "supply voltage".
  4. Connect a jumper wire between the control circuit of the EGR valve at the harness connector, and the corresponding terminal on the EGR valve.
  5. Connect a DMM between the ignition positive voltage circuit of the EGR valve, at the harness connector, and the corresponding terminal on the EGR valve.
  6. Command the EGR duty cycle to 100 percent.
  7. Measure the amperage and note as current flow.
  8. Exit the EGR output control function.
  9. Remove the DMM.
  10. Connect a jumper wire between the ignition positive voltage circuit of the EGR valve, at the harness connector, and the corresponding terminal on the EGR valve.
  11. connect a DMM in parallel between the EGR ignition positive voltage circuit and the B+ terminal on the battery.
  12. Command the EGR duty cycle to 100 percent.
  13. Measure the voltage drop and note as "supply voltage drop".
  14. Subtract the supply voltage drop from the supply voltage and divide your answer by the current flow in order to calculate the resistance in the ignition positive voltage circuit.

Is the calculated resistance more than the specified value?

3 ohms

Go to Step 15

Go to Step 10

10
  1. Connect a DMM in parallel between the control circuit of the EGR valve and a good ground
  2. Measure and note the control circuit voltage drop.
  3. Divide the control circuit voltage drop by the current flow in order to calculate the resistance in the control circuit of the EGR valve.

Is the calculated resistance more than the specified value?

1 ohms

Go to Step 14

Go to Step 17

11

Test the 5-volt reference circuit of the EGR position sensor for resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 16

12

Test the low reference circuit of the EGR position sensor for resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 16

13

Test the signal circuit of the EGR position sensor for resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 16

14

Important: Both of the EGR control circuits between the engine control module (ECM) and the underhood fuse block (UHFB) must have high resistance in order to set this DTC.

Test the EGR valve control circuit for resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 16

15

Repair the resistance in the ignition positive voltage circuit of the EGR valve. Refer to Wiring Repairs in wiring systems

Did you complete the repair?

 

Go to Step 20

--

16

Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 19

17

Test for an intermittent and for a poor connection at the EGR valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 18

18

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

Did you complete the replacement?

--

Go to Step 20

--

19

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 20

--

20
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 90 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 21

21

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK