STRANGE ISSUE: Fog Lights - Non-Functional

[JackalX3]

Alright, long story short, last night I noticed that my fog lights were no longer operating. My vehicle came with fogs from the factory but I have since installed an HID kit.

Both fogs lamps ceased to operate simultaneously, so naturally I figured I had blown a fuse.

- The Fuse (15A) is fine

I then checked the relay by plugging an identical relay (i.e. horn or defroster) into the socket. Nothing. I then plugged the 'questionable' relay into a socket which was known to function (i.e. horn) and the accessory functioned properly.

(The vehicles wiring schematics illustrate that the only fuse/relay is in the fuse box under the hood)

Now is where things get strange...

When I jump the normally open circuit in the relay socket with a piece of wire, the fogs operate perfectly (i.e. bypass the relay). When I measure the two terminals with a volt-meter, I read ~12.5V. The same goes for the 'switching' terminals. I also read ~12.5V when I measure across them.

So, the problem is not the relay or the fuse, nor does it have anything to do with the modifications I've performed.

Any ideas?

The only thing I can think of is that MAYBE it's a current issue. Does anyone know how many Amps the 'switching' side of the relay should read? Again, the value I read when I measure the fog-lamp circuit is identical to other circuits which use an identical relay.

I'm completely stumped on this one... :bang

[Noisy Crow]

Check the high-beam relay.

[JackalX3]

Pretty sure the high-beams run off of a separate circuit...
Regardless, since I don't know what else to try, I gave it a shot.

High-beams function correctly.
When the high-beams are on, the fogs still do not operate.

Stopped by my Mazda dealer for kicks while running some other errands to talk to a few of their guys.

They're completely perplexed...
Needless to say that gave me a warm and fuzzy feeling.

[xxSlidewaysxx]

Crow was trying to say, if the highbeam relay is on the fogs are turned off. As for " Does anyone know how many Amps the 'switching' side of the relay should read?", that depends on the HID's you installed. If they are 35W then you should have close to 6 amps drawn. Where did you get your HID's from?

[Skippy]

With the OEM fogs, don't your headlights have to be on in order for them to turn on? Have you checked the normal headlight relay at all? Are your HIDS functioning properly?

[McGuyver_3]

could be a broken wire between the switch which is controlled by the headlight wire on the drivers side. It should be 12V.
Could be both your HID's are simoultaniously gone. It has happened before.
Could be a broken wire between the headlight switch and the fog relay
Could be a PJB on the way out

[JackalX3]

After trying absolutely everything, I caved and brought the car to the dealer.
They managed to resolve the issue and told me the fuse wasn't making good contact ($160 later).

This was a number of weeks ago. I didn't really question it at that time because I really couldn't disprove that I wasn't just an idiot and didn't properly reinsert the fuse after having played around myself. As I will explain below, I'm pretty sure they gave me a bogus diagnosis and may have totally fluked something.

The other night, the fogs once again ceased to function (both of them).
The EXACT same circumstances of my original post still apply.

Again, when I jump the normally closed circuit, the fogs turn on beautifully. This means that the HID’s and everything downstream of the fuse box (including the 15A fuse itself) is working perfectly fine.
When I check the voltage of the 'switching' side, I read ~12.5V.

I've also tried/checked the high beam circuit relay, etc, as suggested by Noisy Crow & xSlidewaysxx. No dice. The normal headlights operate fine, as do the high beams.

Hmm, déjà vu, because this is exactly what I wrote in my original post.

You'd think the issue was the relay itself at this point, but like I posted originally, when you plug in a good relay, the lights still cease to function. Plugging the 'questionable' relay into a socket for an accessory which is known to function (i.e. the horn) DOES NOT stop the accessory from functioning. The accessory continues to function normally, which means the relay is fine.

The only thing I can think of is that the relay isn't receiving enough current on the switching side to close the switch. However, as I mentioned before, I don't know what that value should be. I may need to connect the relay to a DC power supply and ramp up the voltage slowly until I hear it switch, at which point I can measure the minimum current (i.e. as a control experiment) and determine if I am receiving this input value in the fuse box.

As you can all imagine, this issue has really got me :flaming:bang

(The 'guru' at the dealer who managed to get it working the first time around will be in his motherland the next 3 weeks... FML)

[n00bMeiSter]

I had this exact same problem. I tried my relay in someone else's car and it worked fine. I wired up my indy fog mod and the fog lights work just fine.
Try doing the indy fog mod.

[JackalX3]

Although that would be an easy solution, I really want to avoid that.

It's an OEM issue and I want to resolve it properly. It's not a result of my modifications and as far as I'm concerned, issues such as these shouldn't be happening on a car that has no miles and doesn't see rain, let alone the winter.

Thanks for the suggestion though.

[xxSlidewaysxx]

Where do you live Jackal?

[JackalX3]

Around Weston Rd. & the 401 - Toronto

[xxSlidewaysxx]

I'd offer my support but you're a little too far out of the way................ but you might have some corrosion in the fuse block/ relay connections. Try pulling the relay out and wire it up with pigtail extentions...........if it does not work at first pull the wires out of the sockets and push them back in, do this a few times. Also, you can try some "electronic contact cleaner".... they might have that in CT or The Source...........good luck.

[JackalX3]

One of the first things I tried was cleaning all of the contacts by breaking out the dental tools + a small conical wire brush that fit into the ports.

I also tried to ensure the female spade connectors (embedded within the fuse panel) were tight and made good contact with the male legs on the relay, fuse, etc.

I'm going to try to take a few more measurements, at which point it's looking like I'm going to have to pull the fuse box and trace the harness.

*sigh* :(, I need a bigger garage.

[xxSlidewaysxx]

you could have a damaged wire in the relay block as well. if enough strands of copper are broken then you will not get enough current to flow, thus no lights. I know that block is pretty tight but try to wiggle the wires around from the underside and see if there is any of them that seem "weak". By that I mean see if they all bend in roughly the same spot. If not then the one that does bend differently is probably causing issues.

[JackalX3]

Sounds like we're on the same page man.

I actually tried to investigate exactly what you just suggested earlier this week. I pretty much came to terms with the fact that I'm going to have to deep-dive this issue further than I'd like to (or should have to for that matter). I released the top half of the fuse box housing (I am not referring to the fuse box cover smarta**es :chuckle), only to realize that the harness was pinned by the battery box, hidden 'clip-in' cable ties, etc. As a result, I was unable to rotate the fuse box 180 Deg. to inspect the underside. It then started to spit, so I threw everything back together and tucked the car away before the rain started.

I'm going to have to remove the battery box, free up the harness and try again. Not really a hard job, but it's still quite an ordeal given the issue at hand.

I made a couple probes the other day (i.e. male relay tabs soldered to wires and insulated) to attach to my multimeter so that I can ensure I am making a good connection and obtain accurate readings.

When I find some time, I plan to recheck/record line resistance values, current (with the relay in series), etc. This way, if I do make any changes (i.e. find/repair a frayed wire, etc), I’ll have ‘control’ values to compare new measurements to in an attempt to determine if I've made an improvement.

If anyone has any other suggestions, please let me know.
The way things have been going, I highly doubt I'll find the issue to be as simple as a poor connection/frayed wire.

[JackalX3]

FYI, lets not forget the fact that when I short the 'open' side of the circuit in the relay block with a piece of wire, everything works beautifully.

Everything we're discussing has to be related to the 'switching' or 'coil' side of the circuit.
(As far as I can tell anyway).

[Skippy]

Okay to me it sounds like your using the wrong contact on the relay. The NC contact is going to open when power is put on the coil, and the opposite when your using the NO. Did you install the fogs, or were they stock OEM install?

[n00bMeiSter]

FYI, lets not forget the fact that when I short the 'open' side of the circuit in the relay block with a piece of wire, everything works beautifully.

Everything we're discussing has to be related to the 'switching' or 'coil' side of the circuit.
(As far as I can tell anyway).

Like I said, wire up the indy fog mod and you'll be fine. You're out of warranty so there's no point in trying to keep it completely stock.

One of our studios is near your place, I can have a look at it next time I'm in the area if you'd like. Probably be sometime this week or next.

[TheMAN]

thread is almost 2 months old... maybe he solved the problem by now? :s

[Savage204]

hi guys, i am having the same problem.

my fogs out of the blue stopped working about 2 weeks ago, and now i look out my window and my fog lights are on. both switches are in the off position. fog lights do not even turn off, not even when the high beams are switched on. any ideas? i tried pulling out the relays, but i cant figure out exactly which relay is for the fogs?

[Noisy Crow]

Marked inside the relay box cover under the hood and inside the fuse box (PJB) cover under the glove compartment.