There's been a lot of questions recently about installing the OEM fog/turn signal on Grand Prix's that don't have fog lights from the factory. I'll try to help with this subject.
First off, the actual housing will easily fit into the bumper of a car that doesn't have them from the factory (i.e. just the turn signal). They come out by removing the two screws on each side of the light and the fogs install using the same screws, and the existing turn signal bulb/socket will fit into the upper turn signal housing of the new fog/turn signal housing.
The problem now is wiring the fog lights. This is where you'll need to decide how to turn the fog lights on and off. Factory foglights operate by turning on the parking lamps with the fogs and this is probably the best way to wire them. The advantage of having the fogs come on with the parking lamps is that if you accidentally leave the fogs on after you turn off the car the parking lamp reminder will chime to let you know the lamps are on. To simplify installation you can wire the fogs right to the parking lamps via a relay without a switch. The advantage is that you won't have to run wires through the firewall for a switch. The disadvanatge is that your fog lights will always come on with the parking lamps and then with the headlights (since the parking lamps stay on with the headlights). This can be a problem if you intend to use HID's in the fogs instead of halogens since the fog lamps will flash with the parking lamps when you lock and unlock the car with the keyfob. You can eliminate this problem by turning off the parking lamp flash using the DIC's personal programming, or by adding the aforementioned switch.
Another way to wire the fog lamps is so that they come on with the headlights. Again, this eliminates a switch (unless you want to install one) but the disadvantage is that they will only come on with the headlamps.
Still another way to wire the fogs would be just to bite the bullet and use a switch. You could just run the switch right from the battery but you may accidentally leave them on and forget to turn them off since they aren't connected to the parking lamps and therefore will not chime to remind you that they're on.
RELAYS AND WIRING
No matter how you wire the fogs you need a relay to ensure you don't cook the parking lamps or headlamps or whatever source you use to turn them on.
Relays are simple to wire. For installing foglights you'll want to use a normally open (NO) single pole, single throw relay (SPST) with four pins. These pins are numbered 30, 85, 86 and 87. #30 is the fused source that goes directly to the battery or distrobution block. #85 is the relay's ground, #86 is the relay's trigger, i.e. the parking lamps, headlights, etc. and #87 goes directly to the foglights. The above diagram shows an additional fuse on the wire going to the switch then to the relay's trigger. It's a good idea to add one but it's not imperative since the relay itself only draws milliamps of current.
The above two pictures are examples of automotive relays. The top picture is of two Delco relays with weatherproof sockets. These are for my foglamps and my driving lamps. Great relays but at about $30 a pop a little pricey. The second picture is of a normal automotive relay. The relay itself is sealed and weatherproof but the socket is not. Still a good option to use since the socket and a good relay will run about $10 to $15 depending on where you get them. Both relays do the same thing though.
HALOGEN FOGS
Baseline, GT and GTP Grand Prix's use 898 halogen foglight bulbs. This bulb is a right angle 37.5 Watt capsule with a right angle base and has a cap on its tip to reflect light back into the housing.
^^898 in 2004+ GP foglight housing^^
^^Comparing and contrasting an 894 bulb (left) with an 898 (right).^^
^^This is the kind of socket that the 898 uses. It's also the kind that the H11 uses in the GXP model, but no one gives a **** about GXP's.
The 898 only puts out 37.5 Watts of light which is fairly dim. Alternatively you could use an 886 (I think that's the number), it is identical to the 898 but puts out 50 Watts. The additional heat produced will not damage the fog housing and as long as you use at least 16 gauge wire going to each bulb you won't damage any wiring.
^^Testing a wiring harness for stock GP fogs using 37.5W 898 bulbs. Yellow wire is the relay's trigger (to parking lamps, headlights, etc). The thicker, fused, red wire connects to battery and the smaller red wires go to the lamps. Black wires are common grounds.
For 37.5 Watt systems I recommend 12 gauge wire for the fused connection to the battery, 18-16 gauge wire to the lamps, 18-16 gauge black wire for the ground connections and 20-18 gauge wire for the relay's trigger wire. For 50 Watt halogen and HID fogs I recommend 16-14 gauge wire for the lamps and grounds.
HID FOGS
If you want a lot of light output and or wanna be a dick and put in blue or purple colored fogs then HID's are for you. I personally recommend 4300K (halogen looking) or 3000K (yellow) HID bulbs due to their usable light output. I run with 4300K, myself.
Wiring HID fogs will be similar to running halogens but there are subtle differences. First off, aftermarket HID kits use a 9006 style connector to the ballast. (I'm not going to explain about ballasts, HID bulbs, etc. since that's not the point of this thread.) This connector is different from the 898 connector for the halogen fogs so you'll need to install a 9006 for HID instead of the 898.
RUNNING THE WIRES
I've found that for GM cars it's almost always easier to run the relay harness' fused battery cable to a distribution post instead of the battery.
^^I used the distibution post on top of the engine fuse block to run my fog light HID harness and my driving light harness.
^^ I used weatherproof fuse holders with mounting tabs and I mounted my fog light HID harness to the washer fluid bottle's screw. This ensures that I won't have to search my engine bay for the fuse holder.
^^Nifty spot for mounting headlight ballasts. This isn't relevant to this thread and I said I wouldn't talk about ballasts and HID components but I'm a dick.
^^What I'm holding here is the OEM headlight harness that plugs into the headlight. The small wire coming out the bottom (the one my pinky finger is holding) is the trigger wire that I used for my driving lights behind my grill (I use the highbeams to turn them on). What I'm trying to convey here is that if you choose to use the highbeams or headlamps to turn on your fogs you will find it convenient to splice those wires here BELOW the plug to the headlights. Don't use the wires on the headlamps themself because you won't be able to remove the headlamps completely from the car. Anyway, in this harness there is the headlamp wire, highbeam wire and corner light wire. DON'T USE THE CORNER LAMP WIRE AS A RELAY TRIGGER!!! If you do the fogs will blink with the turn signal and you'll look like a dickfor. Anyway, yellow wire is the headlamp and green is the highbeam (if you choose to use any of those as a trigger). If you choose to use the parking lamps as a trigger splice the BROWN wire near the parking signal bulbs.
I mounted my relays just above the horn and zip-tied them to the factory wiring in an upright position to make them as water resistant as possible.
^^This is where I mounted my fog light ballast (super thin as you can see). The 3 wire connector in front of that is an optional connector that I put on my relay harness for the HID fogs. It made it easier to install, you don't need this, I'm just a dick.
^^This is where the fog light relay harness plugs into the HID ballast. You can also see where I routed the wires across the bumper to get to the other side of the car.
^^This picture shows a little better how I ran the wires across the front of the car. I zip-tied the new wiring to the existing wiring hanress. It's easier to do if you take out the grill inserts.
I imagine that the diagram about halfway up this thread is going to be the most useful to anyone that wants to wire the fogs. I just added pics of my install to give some idea of how to do things but it's entirely up to the individual how they want to do things. Just keep in mind that if you screw something up on your car I'm not the one to blame so don't ***** at me if you screw up.
Oh yeah, here's a link for relays/sockets:
suvlights.com RELAYS & RELAY SOCKETS
Originally Posted by theaceofspades
