GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Chevy K Silverado - 4WD 🢒 Engine 🢒 Engine Controls - 6.6L (LB7) 🢒 DTC P0489

Circuit Description

The exhaust gas recirculation (EGR) valve is vacuum operated. Vacuum for the EGR valve control system is supplied by a belt driven vacuum pump. The EGR valve vacuum control solenoid and the EGR valve vacuum vent solenoid work together to control the position of the EGR valve. The EGR valve vacuum control solenoid is supplied with 12 volts through the ignition 1 circuit. The EGR valve vacuum control solenoid is pulse width modulated through the EGR valve solenoid control circuit by the engine control module (ECM). The ECM monitors the voltage on the EGR valve vacuum solenoid control circuit. If the ECM detects a low voltage condition on this circuit, DTC P0489 sets.

Conditions for Running the DTC
    • The Engine Run Time parameter is more than 0.5 seconds.
    • The Ignition 1 Signal parameter is between 11-18 volts.
    • The EGR Solenoid Command parameter is less than 71 percent.

Conditions for Setting the DTC

The ECM detects a low voltage condition on the EGR valve solenoid control circuit for more than 2 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

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
  1. Turn ON the ignition, with the engine OFF.
  2. Command the EGR Solenoid to 50 percent with a scan tool.

Does the EGR valve vacuum control solenoid click continuously when commanded with a scan tool?

Go to Step 3

Go to Step 4

3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 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 4

Go to Intermittent Conditions

4

Inspect the Fuel HT Fuse.

Is the fuse open?

Go to Step 5

Go to Step 6

5
  1. Disconnect the EGR valve vacuum control solenoid.
  2. Test the Ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  3. If a short to ground is found then replace the fuse.

Did you find and correct the condition?

Go to Step 14

Go to Step 10

6
  1. Disconnect the EGR valve vacuum control solenoid.
  2. Connect a test lamp between the ignition 1 voltage circuit of the EGR valve vacuum control solenoid and a good ground.
  3. Turn ON the ignition with the engine OFF.

Does the test lamp illuminate?

Go to Step 7

Go to Step 8

7
  1. Connect a test lamp between the Ignition 1 voltage circuit of the EGR valve vacuum control solenoid and the control circuit of the EGR valve vacuum control solenoid.
  2. Command the EGR solenoid to 100 percent with a scan tool.

Does the test lamp illuminate?

Go to Step 10

Go to Step 9

8

Repair the open ignition 1 voltage circuit. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

9

Test the control circuit of the EGR valve vacuum control solenoid for an open or high resistance.

Refer to Circuit Testing and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

10
  1. Test for an intermittent and for a poor connection at the EGR valve vacuum control solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
  2. Replace the fuse if necessary.

Did you find and correct the condition?

Go to Step 14

Go to Step 12

11

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 14

Go to Step 13

12
  1. Replace the EGR valve vacuum control solenoid. Refer to Exhaust Gas Recirculation Valve Solenoid Replacement .
  2. Replace the fuse if necessary.

Did you complete the replacement?

Go to Step 14

--

13

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

Go to Step 14

--

14
  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. 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 15

15

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