I've got a tail light bulb that won't come on and I can't figure out what it is. From the bottom to the top, I've got : running light, reverse light, mystery non-working light, brake light, signal light.

(IMG:http://img511.imageshack.us/img511/1880/lightsbc0.th.jpg)

So, what's the non-working light supposed to be? It doesn't work on either side. I have an extra set of bulb holders that I swapped in, and they still don't work. I seem to have at least one of everything working, so it's hard to determine what the one that doesn't work should be. I'm sure everybody but me knows what the light is supposed to be, and hopefully someone will tell me, but does anyone have a guess as to why it wouldn't work given that everything else seems to?
Any thoughts appreciated.
Thanks

Rear Fog Light. You have a button on your dash for it, it probably only works on one side unless you make the hole complete on the other side. Why it will not work on your car I do not know.

Nope. The rear fog is on the left side, bottom light, and that one works.


You lost me there. What hole? There is a way to have rear fogs on both sides?

Dude,

That's supposed to be your running lights. Altogether, you should have four light bulbs for running-lights at the back. Check the connections, the rust may stop current from flowing.

As I understand the "rear fog" light only lights up the driver side (or on mine only the driver side lights up). However, it isnt a separate light from what I can tell, it simply makes one of the driving lights brighter. Onmine the switch is on the left side of the instrument cluster near the top.

Never found much use for it though, except for locking up the gate at work after dark, it helps to illuminate the gate to put the lock on it...haha.

on my seadan the rear fog lights are seperate lights, but one side has a plastic tab in the way preventing you from putting a bulb in there. sometimes i use them to mess with tailgaters :P

I finished cutting out the hole on my ride. I use them when its really foggy as there are a lot of rivers in my area that get foggy and it flows onto the roads, I also live in the mountains where temp change is quite common quickly causing a lot of fog. If I remember correctly one part of the rear lights is just a reflector right?

On the wagon, at least mine, it is on the drivers side, lower bulb. It's one of the running lights, and the socket uses a 2 filament bulb. When you turn the rear fog on, the second filiment lights up super bright. The passenger side uses the same bulb, and the sockets are interchangeable from side to side, so I guess it's in the wiring....gotta look into that one.

Here in the northwest, we get our fair share of rain. The difference in visibility makes a huge difference at times. With all the things the fed's mandate, I'm kinda surprised that this isn't one of those things.


OK, again, can someone explain this 'hole cutting' thing....
Cutting a hole in what, to accomplish what, and related to a rear fog how? :puzzled:


As for my non-working running light, I doubt it's rust related. I have a total of 4 socket holders and about 15 bulbs. I've tried all 4 holders on each side, with every bulb, and those two lights don't work on either side.

i recall that something in the 850 owner’s manual stated that the rear fog lamp is extra bright and is meant to break up the pattern of the rear taillights with its asymmetry and increases the ability of others to see the rear of your vehicle in poor vision driving conditions only.

i have seen some volvo drivers around town that leave it on all the time and the reflector and/or lens is distorted from the heat.

it seems like almost every person with fog lamps drives around with them on all the time i can only speculate that the button looks so much like the other manufacturers fog lamp type switches that these other drivers want to "look" like all the other fog lamp blazers. and push the button to see the red led come on. :blush: :rolleyes: :huh:

for rosso, when you pull out the holders, the passenger side has a hole already there, but there is a plastic bar blocking you putting in a bulb. just cut it out with scissors, and when you press the fog light button on the dash, the other fog light button, usually on the left hand side of the steering wheel, it'll light them both up. and yes, i've messed with tailgaters like that also. besides the infamous brake check trick. be safe, they hate that one.

Going from the bottom lens to the top lens these lights are:

Park/Foglight combination (control switch for rear Foglight on dashboard)
Reverse
Park only
Brake
Indicator

Switching on the front foglights will not switch on the rear foglight - each group of foglights have their own separate control switch.

Hope this helps you out.

Ah, gotcha. Must be a sedan thing though. My wagon has the same sockets on both sides. I'm guessing it's in the wiring somewhere for the wagon.

So I got real friendly with my volt meter today, and learned nothing. The indicators work, as do the brake lights, so I left the top light alone. I pulled the plugs for the bottom lights, and the bulb holders. My bulb holders have the same continuity patterns from each bulb socket to the corresponding pin on the back, so unless I have 4 bad bulb holders, the problem is not there.

I checked the plugs on both sides and I get power from 3 of the 4 wires that should have power (the 5th is a ground). Here's a pic of the plug...
(IMG:http://img410.imageshack.us/img410/5305/socketri5.th.jpg)
On the top, from left to right:
The first is a ground.
The second is the rear fog light. I get 12v there when the light is switched on (if the headlights are on), and the rear fog works.
The third is the reverse light. I get 12v there when the car is in reverse, and the reverse light works.
The fourth does nothing, and that pin on the bulb holder corresponds to the light that isn't working. No matter what I did, I couldn't get 12v at that pin. I tried every combination of headlights, brakes, signals, flashers....anything I could think of. No voltage.
The single pin on the bottom row is the running/parking lights. I get 12v there when I turn the lights on, and my bottom bulb lights up.

So, anybody have a wiring diagram? It's a green wire with a yellow stripe, which is different from the other 4. Seems to me if it were supposed to be a running light, as mentioned above (giving me 4 instead of the 2 I have) it would be the same color as the wire for the other running light.

Any thoughts appreciated.