Fog Light Bulbs

Keeping track of how often I have to change a burnt out fog light bulb.

Bad Bulb

I’m not so sure how long it has been out, but someone told on my way out of the work parking lot tonight that one of the fog lights was unlit. I thought I was pretty conscious about checking to see if I could see two lights reflected in some surface of the car in front of me, but I guess I took it for granted that both lights were working in recent times.

The fog light bulb are standard 55 watt H1 bulbs, but for some reason the first two places I checked (Advanced Auto & Walmart) didn’t have them. Oh, they had the expensive Sylvania Silverstar bulbs for $18-20 each, but I wanted no part of them. Not only have they gotten a slightly bad rap on Miata.net, but if I bought just one the light from the fogs would be different from one another. I just wanted 1 plain ol’ halogen bulb for around $5, not 2 hoity-toity bulbs for $40.

Store number three, Autozone, was the answer. They had one left on the self for $5.99. They only fly in that ointment was the counter help was overwhelmed with customers and no one could break free to check me out. After several minutes a clerk asked if she could help me, but when I said I needed to check out, she said, “Oh, I can’t use the register.” About this time I was tempted to walk out, but considering what I went through to find this bulb, maybe the last one in town, I stuck it out a while longer. Cooling my heels I even considered tossing a ten spot on the counter and walking out, but before I could do anything rash, a certified register professional appeared as if by magic from the back and rang me up.

It took about 45 minutes to replace the bulb because you have to jack up the car, remove the front wheel and unfasten a half dozen screw and bolts to peel back a plastic wheel well liner to allow access to the bulb. If they had 2 bulbs I would bought both of them and changed out the passenger side as well. In my experience they usually go in pairs because they each are on for the same amount of time. Plus because I use the fogs as daytime running lights they are on whenever the car is on during the day, so they get quite a bit of use.

Started down, still down.
Miata Top Transitions since 01/01/05: 239

Fog Lights As DRLs Revisited

Finally accomplished what I set out to do all those weeks ago. To prevent to possible immolation of the dashboard I hooked the same +12v that goes to the fog light relay to where the voltage would be applied to the switch normally (how Mazda does it, just with a different source.) I then hooked the ground from the switch directly to the metal frame where the relays are mounted, bypassing the headlight switch, allowing the fog lights to operate without the need for the low beams to be on. Now if the ignition is on and the switch is pressed, the fog lights are on. I will now train myself to turn them on in the day and off at night, unless of course there is fog.

While I had the combination cruise control and fog light switch out of the dash I swapped the two colored light bulbs. For some odd reason the fog lights had a green lamp and the cruise had an orange one, while when the cruise is active there is a green light in the speedo cluster that says, oddly enough, CRUISE to let you know it is, well, active. My swapperoo matched greens for the cruise. The orange for the fog lights will make sense too when I do the future mod of getting some of that protective film in yellow to put over lights…

Fog Light DRLs

I managed to get my hands on a copy of the wiring diagram for the fog lights and as a bonus the headlight circuits.* I’ve had it for a while, but today I decided to attempt the mod again (my first ended in failure.)

With careful study of the circuit wiring diagrams it looked like for the fog light relay to trip, turning on the fogs, it needed +12v coming from the headlight relay and a ground available when the headlight switch is in low. My ideal situation would be to have an ignition on twelve volts applied to one end of the relay and a ground applied to the other whenever the lights are off. This would disable the fog lights as fog lights, but make them daytime running lights – always on when the car is running and off at night.

First thing I decided to do was cut the red/yellow wire. I really didn’t want to, but I could never get the relay loose from the connector, so snip I did. Hooked up the barrel splice to the +12v wire I found in my original attempt and the red/yellow wire running into the relay connector. Figuring that this would not change any operation as the ground from the headlight switch was still missing, I tested the setup. Much to my surprise when the key was turned to IGN the fogs came on. Not only were they on, but the light in the switch was on, even though the switch was not depressed. I tried turning the lights on, another surprise awaited, as when they came on, the fogs went off (along with the light in the switch.) So I pushed in the fog light switch and the fogs came on, they also went out when I turned on the high beams, just like they are supposed to.

Following the diagram out, I must be getting a ground from somewhere I’m not supposed to be, through either the left front low beam or somewhere in the instrument cluster. Seeing as my +12v is only applied when the ignition is on I won’t be running down the battery or anything. The current draw to trip that relay is probably small enough that I won’t do any damage to anything, but I would still like to know where it is coming from. When we go for a drive tonight I’ll see if I can figure out which one by looking at the headlight and the instrument cluster in the dark.

Fog Light DRL Mod Failure

Today I decided to tackle turning the OEM fog lights into DRLs following the instructions in the Miata.net garage article.

I found the relay under the dash (at least I thought I did) and pulled it free from the mount. I couldn’t figure out how to separate the relay from the connector though. I was going to pop out the red/yellow wire as instructed with its metal end still attached, so I could reverse the mod easy and not have to cut the wire. After struggling for a few minutes I though, what the heck, I’ll cut the wire. First I checked to see if I had some barrel splices to use, I didn’t. I figured I’d wait until I had everything else ready to go before I made a trip to the store.

Next task was to locate a +12v source that is only on when the ignition switch is in the run position. The article mentions he used the radio power wire, but totally fails to mention where it is. Hmmm. There are like 4 other relays in the same area, I don’t know what any of them are for, but one is bound to have a wire that I could use. Turned the key to run and checked for 12 volts. Got one, pink wire. Switched the ignition off, no power, bingo. I even started the car and the 12V goes away while the car is starting. Beautiful. I got a six inch piece of wire and a vampire tap and hooked into my new friend the pink wire.

Seeing as I don’t have any splices I don’t want to cut the red/yellow wire just yet, I’ll try testing it by just pushing my tapped wire into the red/yellow wire connector. I turn the key to run and sure enough there are lights shining on the wall. Yippee. I go around front to admire my handy work and, %@#$, the fogs aren’t on. But the low beams are!?! Now I check to see which page I printed out, as there are instructions in the garage on how to do just this, low beams as DRLs. Nope, I’ve got the right ones. Curious.

Well I wanted DRLS, I got ’em, let’s see if everything else works as advertised. Turn the stalk switch to parking lights and they come on and the lows stay on. Turn the switch to headlights and the lows stay on. With the lights on I hit the fog light switch, they turn on and the lows are still on. Hit the high beams and the fogs go out and the lows are still on.

Cycle thru the routine a couple times. A couple passes through is when I notice that when my new DRLs are on and I turn the headlights on with the switch the light on the wall seems marginally brighter. Can’t really tell how much because it is midday, but definitely brighter. This is something that the folks who have done the lows to DRL conversion complained about. In other cars the DRLs are the lows on reduced voltage so they are not as bright, but the Miata conversion ran the low beams at full power.

Here is where I start to wonder how much current is running through my little 22 gauge jumper. Do I have the right relay? Seeing as the red/yellow wire wasn’t cut, just where was I sending +12v? The instructions said it worked on a 2001 LS, did something change on the 03? So I unhooked the jumper from the red/yellow connector and taped it back. Going to call the dealer tomorrow and see if he will let me copy the fog light circuit diagram…