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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 49 (Engine Control System - 3.8L (Troubleshooting & Diagnosis)) >> Troubleshooting >> Malfunction Indicator Lamp (MIL) Inoperative >> Test Description

Test Description

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 4:  This step tests for a short to voltage on the MIL control circuit. With the fuse removed there should be no voltage on the MIL control circuit.
Malfunction Indicator Lamp (MIL) Inoperative

Step Action Values Yes No
Schematic Reference:  Instrument Cluster Schematics  in Instrument Panel, Gages, and Console or  Engine Controls Schematics 
Connector End View Reference:  Instrument Panel, Gages, and Console Component Views  ,  Instrument Panel, Gages, and Console Connector End Views  in Instrument Panel, Gages, and Console or  Powertrain Control Module (PCM) Connector End Views 
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2 Command the malfunction indicator lamp (MIL) ON and OFF with a scan tool.
Does the MIL turn ON and OFF when commanded with a scan tool?
- Go to Intermittent Conditions  Go to Step 3 
3 Inspect the fuse that supplies voltage to the cluster.
Is the fuse open?
- Go to Step 12  Go to Step 4 
4 
  1. Turn OFF the ignition.
  2. Remove the fuse that supplies voltage to the cluster.
  3. Disconnect the powertrain control module (PCM).
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage from the MIL control circuit in the PCM harness connector to a good ground.
Is the voltage less than the specified value?
0.3 V Go to Step 5  Go to Step 13 
5
  1. Turn OFF the ignition.
  2. Install the fuse that supplies voltage to the cluster.
  3. Turn ON the ignition with the engine OFF.
  4. Connect a 3-amp fused jumper wire between the MIL control circuit in the PCM harness connector and a good ground.
Is the MIL illuminated?
- Go to Step  Go to Step 6 
6
  1. Turn OFF the ignition.
  2. Remove the instrument panel cluster (IPC). Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console.
  3. Probe the ignition voltage circuit of the IPC harness connector with a test lamp that is connected to a good ground.
Does the test lamp illuminate?
- Go to Step 7  Go to Step 14 
7 Test the MIL control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct a condition?
- Go to Step 17  Go to Step 10 
8 Inspect the fuses which supply ignition voltage and battery voltage to the PCM. Refer to Engine Controls Schematics .
Are there any open fuses?
- Go to Step 9  Go to Step 16 
9 Repair the short to ground in the appropriate circuit.
Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
- Go to Step 17  -
10 Test for an intermittent and for a poor connection at the IPC. 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 17  Go to Step 15 
11 Test for an intermittent and for a poor connection at the PCM. 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 17  Go to Step 16 
12 Repair the short to ground in the battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
- Go to Step 17  -
13 Repair the short to voltage in the MIL control circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
- Go to Step 17  -
14 Repair the open in the ignition voltage circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
- Go to Step 17  -
15 Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console.
Did you complete the replacement?
- Go to Step 17  -
16 Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the replacement?
- Go to Step 17  -
17 Turn OFF the ignition for 30 seconds.
Does the vehicle operate correctly, without any MIL illumination?
- Go to Step 18  Go to Step 2 
18 Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?
- Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information System OK