GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 CTS - RHD 🢒 Engine 🢒 Engine Controls - 2.6L and 3.2L 🢒 DTC P0650

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, DTC P0650 will set.

Conditions for Running the DTC
    • The engine is running.
    • The system voltage is between 8-18 volts.

Conditions for Setting the DTC
    • The ECM detects an improper voltage on the circuit that controls the MIL.
    • The condition exists for at least 10 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.

Step

Action

Yes

No

Schematic Reference: Instrument Cluster Schematics in Instrument Panel, Gages, and Console and Engine Controls Schematics

Connector End View Reference: Engine 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

Go to Diagnostic System Check - Engine Controls

2
  1. Turn ON the ignition, 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 Intermittent Conditions

4
  1. Test the MIL control circuit for a short to ground or short to voltage. Refer to Circuit Testing in Wiring Systems.
  2. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

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. Refer to Engine Control Module Replacement .
  3. Connect a 3-amp fused jumper wire between the MIL control circuit and ground.
  4. Turn ON the ignition, 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 in Wiring Systems.
  2. If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

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. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.
  4. Turn ON the ignition, 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 in Wiring Systems.

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
  1. Inspect for poor connections at the IPC harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If a condition is found, repair as necessary. Refer to Connector Repairs in Wiring Systems.

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 in Wiring Systems.
  2. If a condition is found, repair as necessary. Refer to Wiring Repairs in the Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 13

13
  1. Inspect for poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If a condition is found, repair as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 14

14

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

Go to Step 16

--

15

Replace the IP cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

Go to Step 16

--

16
  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.

Does the DTC run and pass?

Go to Step 17

Go to Step 2

17

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