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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1350 (Engine Control System (Troubleshooting & Diagnosis) -- 1.8L (LNK)) >> Troubleshooting >> Malfunction Indicator Lamp (MIL) Inoperative >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 2:  This step checks whether there is communication between the PCM and a scan tool device. If the PCM is unable to provide serial data to the scan tool, there will be no MIL control.
  2. 3:  If other instrument panel cluster (IPC) functions are not working correctly check for an open GAUGE fuse or for a lack of power and ground to the IPC.
  3. 4:  This step checks for an open MIL control circuit or for an internal PCM failure.
  4. 5:  An open fuse determines if a voltage is constantly being applied to the control circuit.
Malfunction Indicator Lamp (MIL) Inoperative

Step Action 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. Connect a scan tool.
  2. Turn ON the ignition, with the engine OFF.
Does the scan tool display any engine data?		 Go to Step 3  Go to Scan Tool Does Not Communicate with VCM/PCM in Data Link Communications
3  Observe the instrument panel cluster (IPC) assembly operation.
Do all other functions of the IPC function normally?		 Go to Step 4  Go to Diagnostic Starting Point - Instrument Panel, Gages and Console in Instrument Panel, Gages and Console
4 
  1. Turn OFF the ignition.
  2. Disconnect PCM electrical connector with the MIL control circuit.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the MIL control circuit on the harness side with a 3-amp fuse jumper wire to ground.
Does the MIL illuminate?		 Go to Step 9  Go to Step 5 
5  Did the fuse in the jumper wire open? Go to Step 6  Go to Step 7 
6 Repair the short to voltage in MIL control circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 10  -
7
  1. Turn ON the ignition, with the engine OFF.
  2. Backprobe the MIL control circuit at the instrument panel cluster (IPC) assembly with a 3-amp fuse jumper wire to ground.
Does the MIL illuminate?		 Go to Step 8  Go to Diagnostic Starting Point - Instrument Panel, Gages and Console in Instrument Panel, Gages and Console
8 Repair the open in the MIL control circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 10  -
9 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?		 Go to Step 10  -
10 Turn ON the ignition, with the engine OFF.
Is the MIL illuminated?		 Go to Step 11  Go to Step 2 
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. Observe the MIL operation.
Is the MIL illuminated?		 Go to Diagnostic System Check - Engine Controls System OK
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