DTC P0650: Mil Control Circuit: Description

Ignition 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. The 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 low, near 0 volts. When the PCM is commanding the component control circuit OFF, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the Diagnostic Trouble Code (DTC) to set.