GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Tracker - 2WD 🢒 DTC 🢒 DTC P0403
Table 1: EGR Valve Terminal (Pin) Identification

Circuit Description

The DTC P0400 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit diagnostic monitors the electrical circuitry of the EGR valve. The exhaust gas recirculation (EGR) system controls the formation of NOx (Oxides of Nitrogen) emissions by recirculating the exhaust gases into the combustion chamber. The EGR valve is a stepper motor design. The stepper motor moves a spring loaded plunger that controls the flow of exhaust gases into the intake manifold. The plunger movement is controlled by the powertrain control module (PCM). By turning the stepper motor in different directions, the PCM controls the opening of the exhaust gas passage to the intake manifold. The stepper motor has four coil windings that control the motor's movement. The DTC P0403 diagnostic monitors the electrical circuits of the four coils.

Conditions for Setting the DTC

The voltage observed by the PCM on the EGR valve coil control circuits is not within the expected values when the ignition is ON.

OR

The voltage observed by the PCM on the EGR valve coil control circuits is not within the expected values, when the engine is running and the PCM requests the EGR valve ON.

Action Taken When the DTC Sets
    • The PCM illuminates the malfunction indicator lamp (MIL) after two consecutive ignition cycles in which the diagnostic runs with the fault active.
    • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC
    • The MIL turns OFF after three consecutively passing trips without a fault present.
    • A History DTC clears after 40 consecutive warm-up cycles without a fault.
    • Use the scan tool Clear DTC Information function or disconnect the PCM battery feed in order to clear the DTC.

Diagnostic Aids

Normal engine operating temperature is specified as 80°C (176°F) or above.

Check for any of the following conditions:

    • The incorrect PCM can cause a DTC P0403 to set. Check that the correct PCM is installed in the vehicle as required for proper emission certification.
    • A faulty electrical connection at the PCM.

An intermittent malfunction may be caused by a fault in the EGR control system electrical circuits. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions .

Use the following table in order to locate the correct terminals to test during diagnosis. The table layout corresponds to the pin location of the EGR valve electrical terminals.

EGR Valve Terminal (Pin) Identification

Connector Lock Tab

Pin 3

Pin 2

Pin 1

Pin 6

Pin 5

Pin 4

Test Description

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

  1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and to store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

    2.

  2. This step checks the ignition positive voltage supply to the EGR coils.

    3.

  3. This step tests the operation of the EGR valve. If the EGR valve responds to commands from the scan tool, and the engine reacts to the valve opening, then the system is operating normally at this time.

    4.

  4. This step determines which EGR coil control circuits may be at fault. If a DTC P0403 resets within 1 minute, the circuits referred to in step 8 or the PCM are at fault. If a DTC P0403 DOES NOT reset within 1 minute, the circuits referred to in step 6 or the PCM are at fault.

Step

Action

Value(s)

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Disconnect the EGR valve electrical connector.
  2. Turn ON the ignition, leaving the engine OFF.
  3. Connect a test lamp between terminal 2 (harness side) and ground.
  4. Connect a test lamp between terminal 5 (harness side) and ground.

Did the test lamp illuminate for both circuits?

--

Go to Step 3

Go to Step 7

3
  1. Use a DMM to measure the following EGR valve coil windings for the specified value of resistance. Refer to the EGR Valve Terminal Identification table in Diagnostic Aids.
    2. • Between pin 1 and pin 2
    • Between pin 2 and pin 3
    • Between pin 5 and pin 6
    • Between pin 4 and pin 5
  2. Measure the resistance between pin 2 and EGR valve assembly, and pin 5 and the EGR assembly. Resistance should be infinite.

Did the EGR valve pass all resistance tests?

20-24 ohms at 20°C (68°F)

Go to Step 4

Go to Step 9

4

  1. Connect the EGR valve electrical connector.
  2. Install a scan tool.
  3. Start the engine.
  4. Operate the engine to attain normal operating temperature.
  5. Perform the scan tool Clear DTC Information function.
  6. Using the scan tool, gradually command the EGR valve OPEN to 100 percent.

Did the engine run rough or stall?

--

Go to Diagnostic Aids

Go to Step 5

5

  1. Perform the scan tool Clear DTC Information function.
  2. Start the engine.
  3. Operate the engine for one minute, or until the MIL illuminates.
  4. Check for DTCs.

Is a DTC P0403 set?

--

Go to Step 8

Go to Step 6

6
  1. Inspect the EGR coil control circuits C4-14 and C4-15 for an open or a short circuit.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 11

Go to Step 10

7

Repair the open in the ignition positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 11

--

8
  1. Inspect the EGR coil control circuits C4-13 and C4-16 for an open or a short circuit.
  2. Inspect the EGR coil control circuit C15 for a short to ground.
  3. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 11

Go to Step 10

9

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

Is the action complete?

--

Go to Step 11

--

10

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 11

--

11
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 12

Go to Step 2

12

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK