GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Catera 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 DTC P0650

Circuit Description

There should always be a steady malfunction indicator lamp (MIL) when the ignition switch is ON and the engine is not running. The ignition voltage is supplied within the instrument cluster to the indicator bulb. The engine control module (ECM) controls the lamp by grounding the control circuit via an internal solid state device called a driver.

Conditions for Running the DTC
    • The engine speed must exceed 40 RPM.
    • The battery voltage must be between 7.5-14 volts.

Conditions for Setting the DTC

The ECM determines there is an open, a short to ground, or a short to voltage in the MIL control circuit.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • 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
    • 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.

Diagnostic Aids
    • Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
    • If the ignition feed circuit is suspected of being open, check if the other bulbs on that circuit illuminate.
    • Check to see if instrument panel fuse 15 is open.
    • An intermittent may be caused by the following:
       - Corrosion
       - A mis-routed harness
       - A rubbed through wire insulation
       - A broken wire inside the insulation

Refer to Testing for Intermittent Conditions and Poor Connections for the intermittents.

Test Description

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

  1. The MIL should remain ON when the ignition is turned ON and the engine is OFF.

    2.

  2. If the other indicator lamps in the instrument cluster are functioning, the feed circuit is OK.

    3.

  3. After the engine starts, the MIL should illuminate briefly and turn OFF.

DTC P0650 Malfunction Indicator Lamp (MIL) Control Circuit

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

Turn ON the ignition, with the engine OFF.

Does the MIL illuminate?

Go to Step 6

Go to Step 3

3

Check the fuse for the instrument cluster ignition feed circuit.

Is the fuse OK?

Go to Step 4

Go to Step 9

4
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Turn ON the ignition.
  4. Use a fused jumper in order to jumper the MIL control circuit in the ECM harness connector to ground.

Is the MIL ON?

Go to Step 10

Go to Step 5

5

Check for the following conditions:

    • A damaged bulb. Refer to Instrument Cluster Indicator Lamp Replacement in Instrument Panel, Gauges, and Console.
    • A control circuit open or shorted to B+. Refer to Wiring Repairs in Wiring Systems.

Did you complete the action?

Go to Step 12

--

6

Command the MIL OFF using the scan tool.

Does the MIL turn OFF?

Go to Diagnostic Aids

Go to Step 7

7
  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Turn ON the ignition, with the engine OFF.

Does the MIL illuminate?

Go to Step 8

Go to Step 10

8

Repair the short to ground in the MIL control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 12

--

9

Repair the short to ground in the feed circuit to the instrument panel indicator lamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 12

--

10

Test for poor connections or poor terminal tension at the ECM harness connector. 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 12

Go to Step 11

11

Important: 

   • Perform the idle learn procedure when replacing the ECM or throttle body.
   • This vehicle is equipped with a theft deterrent system which interfaces with the engine control module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle.

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the action?

Go to Step 12

--

12

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 13

Go to Step 2

13

With a scan tool, observe the stored information, Capture Info.

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

Go to Diagnostic Trouble Code (DTC) List

System OK