GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Sonoma Pickup - 2WD 🢒 Engine 🢒 Engine Controls - 2.2L 🢒 Malfunction Indicator Lamp (MIL) Always On

Object Number: 387307 Size: LF
Engine Controls Components
Cell 20: Power, Grounding, Generator and MIL
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

When the ignition is turned ON, the malfunction indicator lamp (MIL) will momentarily flash ON then OFF and remain ON until the engine is running, if no diagnostic trouble codes (DTCs) are stored. The powertrain control module (PCM) controls the MIL by providing a ground path through the MIL control circuit to turn ON the MIL.

Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

  1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this information for later reference.

    2.

  2. When the ignition switch is turned ON, the MIL should momentarily flash ON and OFF, then remain ON until the engine is running or if an emission related DTC stores.

    3.

  3. This step checks the ability of the PCM to control the MIL. The scan tool has the ability to command the MIL ON and OFF.

    4.

  4. A shorted MIL circuit can be diagnosed with a scan tool.

    5.

  5. Program the PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Techline information for PCM programming.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Turn ON the ignition leaving the engine OFF.

Is the MIL ON?

--

Go to Step 3

Go to Malfunction Indicator Lamp (MIL) Inoperative

3

  1. Install a scan tool.
  2. Select Special Functions Outputs/MIL.
  3. Command the MIL ON and OFF with the scan tool.

Does the MIL turn ON and OFF when commanded?

--

Go to Step 8

Go to Step 4

4
  1. Turn OFF the ignition.
  2. Disconnect the PCM harness connectors.
  3. Turn ON the ignition leaving the engine OFF.

Is the MIL OFF?

--

Go to Step 7

Go to Step 5

5

  1. Check the MIL control circuit for a short to ground.
  2. Repair the circuit if necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 8

Go to Step 6

6

Replace the Instrument Panel Cluster (IPC). Refer to the Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Is the action complete?

--

Go to Step 8

--

7

Important:: The replacement PCM must be programmed. Refer to the Powertrain Control Module Replacement/Programming .

  1. Turn OFF the ignition.
  2. Replace the PCM.

Is the action complete?

--

Go to Step 8

--

8
  1. Turn ON the ignition leaving the engine OFF.
  2. Using the scan tool, clear the DTCs.
  3. Attempt to start the engine.

Does the engine start and continue to run?

--

Go to Step 9

Go to Step 1

9
  1. Idle the engine until the normal operating temperature is reached.
  2. Check to see if any DTCs are set.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to the applicable DTC table

System OK