Fog lights not working on a 98 Toyota avalon

Your local Toyota dealer’s parts guy will have wiring diagrams AND schematics (you’ll need both) for them. He also should have a procedure for installing the optional fog lamps. Ask nicely and they’re usually happy to print a copy for you.

You’re probably going to have to buy an additional Toyota wiring harness that will plug into an already-existing plug in a wiring harness behind your dash, as well as a Toyota relay. You’ll then need to find (using the wiring diagram) the fog light plug in the wiring harness under the front of the car. This will be two wires, one hot and the other ground (it doesn’t use the chassis ground at this point in the circuitry).

I can tell you from experience that the connectors, wiring harness, and relay are not cheap, but you will not find an aftermarket source. And I recommend you do it right or the fog lights won’t go off when you turn the key OFF, or go off when you turn the high beams on (lessening the total current draw). You could easily configure your own wiring, but I’d suggest doing it right.

For the record, I wanted to buy the connectors and build my own wiring harness. I have the technical knowledge, including IPC 610C and J-STD- 001 expertise, had the part numbers, and even have the pin-pushers to install the pins. I researched all the way down to Toyota’s connector part numbers… and when the parts guy looked them up the Toyota documents said Toyota would not sell the connectors separately. I tried going to the major connector manufacturer catalogs, but the part is Toyota proprietary and I could not match the connectors. In short, I had the connector part numbers, their interface drawings, and still could not get the connectors. I gave up and ordered the Toyota wiring harness.