I've been running a OEM 'style' foglight kit for my Civic for a few months without any hitches. But recently, passenger side light no longer works and then very soon after, the driver's side one doesn't work either. I'm guessing it might be a faulty switch, but I don't really know. How can I diagnose this to find the problem?

 

Did you check the bulbs? Did you check the grounds? Exactly how is it wired?

 

One not working isn't switch related. OEM "style" are just cheap lights. I had one go out, just bought another pair.

 

I haven't had the chance yet to remove the bumper to check the bulbs. Everything was plug and play with the original car's harnesses.

I suspect the switch because the switch's on light does not light up when the switch is depressed. But I'm not sure if it's the switch or if it's a relay somewhere, or even a faulty wire somewhere.

 

A light built into the switch is a horribly inaccurate way to diagnose. Check the bulbs, work from there.

 

I would start with the bulbs, good luck!

 

Check the inline fuse.

 

Not a faulty switch because your passenger went out first and then the driver side. You SHOULD start checking the bulbs and, as Ron state, check the inline fuse.

 

I'll check the bulbs soon, I guess I would be surprised if both bulbs burned out within days of each other. I'm not sure if it is a fuse problem but I'll check; the switch is still receiving power because the switch's passive light still turns on; but when toggled, the fog light "ON" light does not change status.

I have also heard that these switches are not good quality and should buy an OEM switch. I have also heard people having problems with relays that are connected to the foglights. Anyone know which/where that relay would be?

 

You don't get it, the when you hit the switch it suppose to power both foglights. But you stated that "the passenger side went out and then the driver side died later". To me that does not sound like a relay issue, or a switch issue. If it were a relay issue than your Chinese harness must have two relays, not 1.

Relay should be located on the harness itself, didn't you install this kit?

 

I installed this myself but quite some time ago. And I have been learning how to do a timing-belt install. So any information I learned about installing this fog light kit quickly left my mind.

I can hear the relay clicking when I push the foglight switch, does this rule out any issues with the relay and/or switch?

 

You need to confirm power is making its way to the foglights, get a dmm and test for power at the foglights.

 

Or just go remove and inspect the bulb like everyone else had suggested. Instead of throwing guesses around. I don't understand why you didn't do that first. Then move on to the next step. Check inline fuse. Check ground cable on the kit. My last fog kept blowing bulb on the driver side, after inspecting, it was the ground cable being rusted and also moisture build up around the positive connector of the driver side fog. Once clean and relocate both wires, no more issue since..

Simple really. Bulb out on one side? Check bulb first..
Check inline fuse
Check fog connectors for moisture
If all check out with 0 issue.. Then
Check relay
Then switch.. The switch may not light up because that bulb is burnt.
You will still get power though.