installing fog light kit on 2018 rav4 le, I purchased the lights the relay and the factory headlight/fog light switch, they do not go on fuses and relays were checked all were good is there something else that has to be done to get the fog lights to work threw this switch.
The Toyota fog light kit includes wiring, one of the wires in the overlay harness goes into an empty cavity in one of the body ECU connectors. The kit has a fog light switch that is to be installed in the dash next to the panel dimmer switch.
The vehicle harness may not be complete, you may not be able to just add the parts and make the fog lights work without the proper kit.