Circuit/System Description

There are 2 ignition 1 voltage circuits supplied to the engine control module (ECM). The first ignition 1 voltage circuit is provided by the engine control relay, through the engine sensor fuse, located in the underhood fuse block. This ignition 1 voltage circuit supplies power to all the internal ECM circuits associated with the throttle actuator control (TAC) operation, and to both TAC motor control circuits to the throttle body. The ignition switch provides the second ignition 1 voltage circuit, to power all the other internal ECM circuits except those, which are used for TAC operation. The ECM continuously monitors both ignition 1 voltage circuits. If the ECM detects a voltage level difference between the 2 circuits, DTC P1682 will set.