Circuit/System Description

The powertrain relay, which is P/Train relay 40, is a normally open relay. The relay switch is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the relay switch contact at all times. The powertrain control module (PCM) supplies the ground path to the relay coil control circuit through an output driver module (ODM). The ODM for the powertrain relay also incorporates a fault detection circuit, which is continuously monitored by the PCM. The ignition 1 voltage that is supplied to the PCM provides power for the throttle actuator control (TAC) system. The PCM also monitors the voltage level on the ignition 1 voltage circuit to confirm that the powertrain relay contracts have closed.