Electronic Back Light (EBL) relay

The rear defogger switch is part of the Automatic Temperature Control (ATC). When the ignition switch is in the RUN position and the rear defogger switch is turned on, the ATC sends a PCI Bus message to the IPM. The EBL relay is then powered through low side control internal to the IPM. The relay provides the power to the rear window defogger grid, and ground is attached to the vehicle body. The IPM will only allow the rear defogger to operate in the RUN position. This circuit is electronically controlled and continuously monitors the coil side of the relay for malfunctions.