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Home >> Cadillac >> 2006 >> STS Base, 3.6 7, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 5 (Engine Control System - 4.6L (LH2) - Troubleshooting & Diagnosis) >> Malfunction Indicator Lamp (MIL) Inoperative >> MIL Operation

MIL Operation

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

The MIL is located on the IPC.

MIL Function

MIL Illumination

Malfunction Indicator Lamp (MIL) Inoperative

Step Action Values 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 - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2 Turn ON the ignition, with the engine OFF.
Is the instrument cluster completely inoperative?
- Go to Symptoms - Instrument Panel, Gages and Console in Instrument Panel, Gages, and Console Go to Step 3 
3
  1. Turn ON the ignition, with the engine OFF.
  2. Command the MIL ON and OFF with a scan tool.
Does the malfunction indicator lamp (MIL) turn ON and OFF when commanded with a scan tool?
- Go to Intermittent Conditions  Go to Step 4 
4 Inspect the fuse that supplies voltage to the cluster.
Is the fuse open?
- Go to Step 11  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Remove the fuse that supplies voltage to the cluster.
  3. Disconnect the engine control module (ECM).
  4. Turn ON the ignition with the engine OFF.
  5. Measure the voltage from the MIL control circuit in the ECM harness connector to a good ground.
Is the voltage less than the specified value?
1 V Go to Step 6  Go to Step 12 
6
  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 ECM harness connector and a good ground.
Is the MIL illuminated?
- Go to Step 10  Go to Step 7 
7
  1. Turn OFF the ignition.
  2. Remove the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.
  3. Turn ON the ignition.
  4. Probe the voltage supply 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 8  Go to Step 13 
8 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 16  Go to Step 9 
9 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 16  Go to Step 14 
10 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 16  Go to Step 15 
11 Test all circuits and components that use this voltage supply for excessive current draw. Refer to Circuit Testing andWiring Repairs in Wiring Systems.
Did you find and correct the condition?
- Go to Step 16  -
12 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 16  -
13 Repair the open in the voltage supply circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
- Go to Step 16  -
14 Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.
Did you complete the replacement?
- Go to Step 16  -
15 Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the replacement?
- Go to Step 16  -
16
  1. Turn the ignition OFF for 30 seconds.
  2. Start the engine.
Does the MIL operate correctly?
- Go to Step 17  Go to Step 2 
17 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