DTC P0650: Malfunction Indicator Light Control Circuit: Description

Ignition voltage is supplied directly to Malfunction Indicator Light (MIL). PCM controls MIL by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply ground for the component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage of control circuit should be low, about zero volts. When PCM is commanding control circuit to a component off, voltage potential of circuit should be high, about battery voltage. If fault detection circuit senses a voltage other than what is expected, fault line status will change causing DTC to set.