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Home >> Chevrolet >> 2004 >> Avalanche 2500 >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Control System - 4.8L, 5.3L & 6.0L (Troubleshooting & Diagnosis)) >> Diagnostic Information and Procedures >> Malfunction Indicator Lamp (MIL) Always On >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The number below refers to the step number on the diagnostic table.

  1. 2:  This step determines if the condition is with the MIL control circuit or the PCM.
Malfunction Indicator Lamp (MIL) Always On

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Engine Controls Connector End Views  or  Powertrain Control Module (PCM) Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? Go to Step 2  Go to Diagnostic System Check - Engine Controls
  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the MIL.
Is the MIL illuminated?
Go to Step 3  Go to Step 5 
3
  1. Remove the instrument panel cluster (IPC). Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console.
  2. Test the MIL control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 6  Go to Step 4 
4 Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console.
Did you complete the replacement?
Go to Step 6  -
5 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?
Go to Step 6  -
6
  1. Turn the ignition OFF for 30 seconds.
  2. Start the engine.
Does the vehicle operate correctly without any MIL illumination, and without any stored DTCs?
System OK Go to Diagnostic System Check - Engine Controls