Circuit/System Description
The engine controls (EC) ignition relay, or powertrain relay 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 switch 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. When the ECM commands the relay ON, ignition voltage is supplied to the following fuses in the underhood fuse block:
- ETC/ECM Fuse
- EMM DEV 1 Fuse
- EMM DEV 2 Fuse
- EVEN COIL/INJ Fuse
- ODD COIL/INJ Fuse
The ignition voltage that is supplied to the ECM through the ECM fuse, provides power to the internal ECM circuits associated with the throttle actuator control (TAC) operation.