DTC P0650 Malfunction Indicator Lamp (MIL) Control Circuit

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Circuit Description

A voltage is supplied directly to the malfunction indicator lamp (MIL). The powertrain control module (PCM) controls the lamp by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be near 0 volts. When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.

Conditions for Running the DTC

Conditions for Setting the DTC

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

Test Description

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

  1. Command both the ON and the OFF states. Repeat the commands as necessary.
  1. If you do not find trouble in the control circuit or the connection at the PCM, the PCM may be faulty. However, this is an extremely unlikely failure.







Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?


Go to Step 2

Go to A Powertrain On Board Diagnostic (OBD) System Check



If the I/P is completely inoperative, refer to Instrument Cluster System Check in Instrument Panel, Gauges and Console for further diagnosis.

  1. Turn ON the ignition leaving the engine OFF.
  2. Command the lamp ON and OFF using the Scan tool.

Does the lamp turn ON and OFF with each command?


Go to Diagnostic Aids

Go to Step 3


  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C1 located on the opposite side of the manufacturer's logo. Refer to PCM Replacement/Programming .
  3. Turn ON the ignition.

Is the lamp OFF?


Go to Step 4

Go to Step 5


Probe the lamp control circuit in the PCM harness connector with a fused jumper wire connected to ground. Refer to Using Fused Jumper Wires in Wiring Systems. Is the lamp ON?


Go to Step 6

Go to Step 7


Repair the short to ground in the lamp control circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete?


Go to Step 9



  1. Inspect for poor connections at the PCM. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. If you find a poor connection repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?


Go to Step 9

Go to Step 8


Inspect for the following conditions:

  • Faulty indicator
  • Open ignition feed to the indicator
  • Control circuit open or shorted to B+
  • If you find a condition, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?


Go to Step 9




Program the replacement PCM. Refer to PCM Replacement/Programming .

Replace the PCM. Is the action complete?


Go to Step 9



  1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC option using the scan tool.
  2. Idle the engine at the normal operating temperature.
  3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
  4. Operate vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test passed?


Go to Step 10

Go to Step 2


Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed?


Go to the applicable DTC table

System OK