Circuit Description

The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an output driver module (ODM). When the ECM commands the powertrain relay ON, ignition 1 voltage is supplied to the ECM through the ECM 2 fuse in the underhood fuse block. This ignition 1 voltage input to the ECM provides the ignition power for the throttle actuator control (TAC) circuitry, and is also used to confirm the powertrain relay contacts have closed. This DTC will set when the ECM detects less than 10 volts on the ignition 1 voltage circuit to the ECM, after the ignition switch is turned ON. DTC P0689 indicates an open, high resistance, or short to ground in the ignition 1 voltage circuit to the ECM.