I drove to Advance and swapped out the bulbs on both lamps, but that didn't work. The problem must be in the wiring. No fuses are blown. Any ideas?

Have you checked for power/ground at the connectors? If its not there, back your way up the wires to see where it ends then fix it there....Luck!

First, tell me you used a meter, test light or a known good fuse to decide FOG fuse is good. If you just looked at it and called it good, you may have wasted my time and everybody else who reads this thread.

Second, use a DMM or test light at the bulb sockets to see if problem is on ground side (black/white) or power side (purple).

If ground side, trace black/white wire back to ground.

If power side, then go to fog relay in main fuse box. It's a standard Bosch type relay. Ground Pin 2 with fogs switch on and Heads on Low.

If lights come on, problem is in switch.

If not, problem is in relay or wiring from relay to light. Check for power at Pin 1 just to rule out lack of coil power from headlights on Low. Then check for power at Pin 5. If those are both good, problem is in purple wire between relay Pin 3 and connector E2 behind battery where wires to left and right fogs split.

Easy Peasy. But post back if you need help. You DO need a test light or meter.

Here is wire diagram.

Attached Images

021ffl.pdf (17.4 KB, 112 views)

Same issue here, I know I have seen past threads about it but I don't remember a common point of failure. I finally got myself a voltmeter just haven't had a chance to troubleshoot it. Please share if you find anything enlightening.

I have a 98 bumper on my 02. The bulb grounds to the housing. I was getting one fog not coming on, despite the filament looking great. I scratched the contact points of the housing, where it mates with the bulb flange, and things worked fine after that. Hopefully this helps.

my factory fogs (Hellas?) had some exposed wiring inside the housing causing a short.
Tidied everything up and re-wrapped the wires and all was well.

As easy as pie, cup of coffee walk in the park. Seriously, @TheDurk outlined it very well, it is not difficult, just requires a little patience and the ability to read his post.

GVL I could diagnosis it for you over a cup of coffee Saturday morning while my girlfriend sleeps in if you wanted to take a 75 mile drive! LOL Sure wish I had the time to run up there and visit you!

cool, i'll try that thanks

Will check tomorrow. Hopefully just a ground fault at light housing...thx

Spent half the day isolating with voltmeter. Really sucked. Finally decided it was the relay, located near the battery, mounted on the engine compartment/fender wall. The DMM/voltmeter didn't show any consistency in regards to resistance. Advanced had a generic relay that didn't help. Where I removed the old relay, I jumped the green to yellow, with speaker wire, and the lights are on, but dim, and correctly turn on, then off with high beam. Replaced old rocker switch with new one. Guess I'll order a new relay from Toyota parts east. What a pain in the arss. Noticed a red wire running from the bad relay, toward lights, and through conduit, but can't determine where that terminates. And YES, I looked at that guy's diagram, I friggin hate electric. Whatever, over it. The whole thing will probably melt before I get it fixed right.

Thanks for the effort @tommyt4r , sounds like you got a bit fed up with the issue but made some good progress. I realized after removing my bumper (new winch bumper on the way) that I won't have fogs anymore, but I would like to use that switch and wiring for some LED's up front so I'm glad you narrowed it down - I'll have to try the same thing and see what happens.

Thanks for sharing your hard earned findings

Good luck with the LED's. I think I'll disconnect my ghetto jumper. No sense in cooking the lights, and wires, when there's no emergency involved. I also noticed that when I hit the switch 'on' for fog lamps; my low beams seem to lose power.

BTW - The relay, (engine comp. next to battery) is HELLA brand.

Just bought a $10 hella relay on ebay. To read the darn numbers, I had to put a piece of paper over the relay and scratch with a pencil! Anyway - the serial# is: 4RA003510-08. It's a 4 pin 30A/12V. It's not an oem part, but hopefully (my favorite word lately) it'll work.

Heh, you are probably routing your low beam tap to providing the power to the fogs. This is not a good way to roll. You are probably running the fogs and low beams in series, hence the dim lights on both.

I'd love to help but you have not provided enough info to allow anyone on here to really help other than guesses and saying what worked for their cousin's boyfriend. Clearly, your '97 is very different that the '99-'02 OEM fogs I am used to. Take some close up pictures of the relay, the socket and its wires, including any markings/diagrams, and I'll tell you what to do with that meter to find the problem.

EDIT: I see now you are going to try a new relay. I hope it works--I don't really understand how you decided the old one was bad, but you might get lucky. They do die. Anyway, the offer stands if it doesn't work.

This is a standard Bosch-type relay.

A generic Echlin from NAPA would have been better quality and no shipping. I don't know if Hella makes their own relays, but they aren't great, in my experience.