Circuit Description
The malfunction indicator lamp (MIL) is a light emitting diode (LED) that 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. For example, a failure condition exists if the control module detects low voltage when the MIL is commanded OFF, or high voltage when the MIL is commanded ON. If the control module detects an improper voltage on the MIL control circuit, DTC P0650 will set.
DTC Descriptors
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 400 RPM. |
| • | The ignition voltage is between 10-18 volts. |
| • | DTC P0650 runs continuously when the above conditions are 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. |
| • | The conditions are present for a minimum of 5 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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for an open in the MIL control circuit. With the powertrain control module (PCM) disconnected and the ignition ON, the MIL should be OFF.
-
This step tests for a short to ground in the MIL control circuit. With the powertrain control module (PCM) disconnected and the ignition ON, the MIL should be OFF.
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-Engine Controls? | -- | Go to Step 2 | |
2 |
Important: This step assumes that the only DTC present is DTC P0650. Start the engine and observe the MIL. Does the MIL stay illuminated with the engine running? | -- | Go to Step 7 | Go to Step 3 |
3 |
Does the MIL turn ON and OFF when commanded with a scan tool? | -- | Go to Step 4 | Go to Step 5 |
4 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions |
Is the voltage measured at the specified value? | B+ | Go to Step 11 | Go to Step 6 | |
6 | 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 13 | Go to Step 9 |
7 |
Is the MIL OFF? | -- | Go to Step 12 | Go to Step 8 |
8 | Test for a short to ground in the MIL control circuit. Refer to Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Step 13 | Go to Step 10 |
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 13 | Go to Step 10 |
10 | Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | -- | Go to Step 13 | -- |
11 | Test for an intermittent and for a poor connection at the PCM. 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 13 | Go to Step 12 |
12 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 |
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
