For 1990-2009 cars

### Circuit Description

The malfunction indicator lamp (MIL) is located on the instrument panel cluster (IPC). The MIL informs the driver that an emission system fault has occurred and that the engine control system requires service. The control module monitors the MIL control circuit for conditions that are incorrect for the commanded state of the MIL. If the control module detects an improper voltage on the MIL control circuit, DTC P0650 will set.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0650 Malfunction Indicator Lamp (MIL) Control Circuit

### Conditions for Running the DTC

• | The engine is running.

• | DTC P0650 runs continuously when the above condition is met.

### Conditions for Setting the DTC

The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match for 12 seconds.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

### Test Description

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

1. This step tests for a short to ground in the MIL control circuit. With the engine control module (ECM) disconnected and the ignition ON, the MIL should be OFF.

2. 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.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain 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
2 |

1. Verify whether the instrument cluster is operational. If the instrument panel (I/P) is completely inoperative, inspect the fuse that supplies voltage to the I/P.
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 Step 3

Go to Step 4

3 |

1. Observe the Freeze Frame/Failure Records for this DTC.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4 |

1. Turn OFF the ignition.
2. Disconnect the powertrain control module (PCM). Refer to Powertrain Control Module Replacement .
3. Turn ON the ignition.

Is the MIL OFF?

--

Go to Step 5

Go to Step 10

5 |

1. Remove the fuse that supplies voltage to the instrument panel cluster (IPC).
2. Measure the voltage from the MIL control circuit to a good ground.

Is the voltage less than the specified value?

1 V

Go to Step 6

Go to Step 11

6 |

1. Turn OFF the ignition.
2. Install the fuse that supplies voltage to the IPC.
3. Turn ON the ignition, with the engine OFF.
4. Connect a 3-amp fused jumper wire between the MIL control circuit of the PCM and a good ground.

Is the MIL illuminated?

--

Go to Step 9

Go to Step 7

7 | Test the MIL control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct a condition? | -- | Go to Step 14 | Go to Step 8
8 | Test for an intermittent and for a poor connection at the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12
9 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13
10 | Test for a short to ground in the MIL control circuit. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12
11 | Repair the short to voltage in the MIL control circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 14 | --
12 | Replace the IPC. Refer to Instrument Cluster Replacement . Did you complete the replacement? | -- | Go to Step 14 | --
13 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 14 | --
14 |

1. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 15

15 | 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 | System OK