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 engine control module (ECM) monitors the MIL control circuit for conditions that are incorrect for the commanded state of the MIL. For example, a failure condition exists if the ECM detects low voltage when the MIL is commanded OFF, or high voltage when the MIL is commanded ON. If the ECM detects an improper circuit condition on the MIL control circuit, this DTC sets.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0650 Malfunction Indicator Lamp (MIL) Control Circuit

### Conditions for Running the DTC

• | The engine speed is more than 80 RPM.

• | The ignition 1 voltage is between 10-18 volts.

• | The ECM has commanded the MIL ON and OFF at least once during the ignition cycle.

• | DTC P0650 runs continuously once the above conditions are met.

### Conditions for Setting the DTC

• | The ECM detects an open, a short to ground, or a short to voltage on the circuit that controls the MIL.

• | The condition exists for at least 4 seconds.

### Action Taken When the DTC Sets

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | 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.

### Diagnostic Aids

• | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.

• | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views .

• | For an intermittent condition, refer to Intermittent Conditions .

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Engine Controls Schematics or Instrument Cluster Schematics Connector End View Reference: Engine Control Module Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Turn the ignition switch to ON position, with the engine OFF.
2. Observe the malfunction indicator lamp (MIL) on the instrument panel cluster (IPC).

Is the MIL illuminated?

Go to Step 3

Go to Step 5

3 | Command the MIL OFF with a scan tool. Is the MIL illuminated? | Go to Step 4 | Go to Diagnostic Aids
4 |

1. Test the MIL control circuit for a short to ground or short to voltage. Refer to Circuit Testing .
2. If a condition is found, repair as necessary. Refer to Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 13

5 |

1. Turn OFF the ignition.
2. Disconnect the engine control module (ECM) connector.
3. Connect a 3-amp fused jumper wire between the MIL control circuit and the ECM housing.
4. Turn the ignition switch to ON position, with the engine OFF.

Is the MIL illuminated?

Go to Step 7

Go to Step 6

6 | Does the fuse in the jumper wire open? | Go to Step 7 | Go to Step 8
7 |

1. Test the MIL control circuit for a short to voltage. Refer to Circuit Testing .
2. If a condition is found, repair as necessary. Refer to Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 13

8 |

1. Turn OFF the ignition.
2. Connect the ECM connector.
3. Disconnect the IPC connector.
4. Turn the ignition switch to ON position, with the engine OFF.
5. Probe the ignition 1 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 10

Go to Step 9

9 | Repair the open in the IPC ignition 1 voltage circuit. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 16 | --
10 |

1. Connect a test lamp between the ignition 1 voltage circuit and the MIL control circuit of the IPC harness connector.
2. Command the MIL ON and OFF with a scan tool.

Does the test lamp turn ON and OFF?

Go to Step 11

Go to Step 12

11 | Test for an intermittent and for a poor connection at the IPC harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 15
12 |

1. Test for an open MIL control circuit. Refer to Circuit Testing .
2. If a condition is found, repair as necessary. Refer to Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 13

13 | Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 16 | Go to Step 14
14 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 16 | --
15 | Replace the IPC. Refer to Instrument Cluster Replacement . Did you complete the replacement? | Go to Step 16 | --
16 |

1. Clear any 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.

Does the DTC fail this ignition?

Go to Step 2

Go to Step 17

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 | System OK