This will more than likely happen to everyone with a SyTy sooner or later. With over 99,000 miles on it, one of my original foglights decided to jump in front of a rock. It put a nice hole all the way through the lens with three large cracks spreading out from that. From what I'd heard, the GM parts were no longer available or overpriced and the best choice was to use the Blazer brand foglights from Wal-Mart or a similar store. Taking their word for it, I picked up a set for $17.96 last weekend. The part numbers on the upper right corner of the package are 20-3591-6 and C1073 KBM if you're not sure what to get. The installation of the new lights is pretty straightforward. You just need to pull out the original lens and reflector assembly and replace it with the Blazer pieces.
The first thing you'll want to do is get your tools around. Using my method you'll need a wire cutter/stripper/crimper, a T-15 Torx driver, small and large Phillips screwdrivers, two 3/16" male spade terminals, and possibly some electrical tape or equivalent insulator (heatshrink, etc.).
Once you have all your parts around, you can dissect the new Blazer lights to get the parts you need. Start by using the larger screwdriver to remove the screws holding the side trim pieces on, which in turn hold the light in the plastic housing. Now that you've got the light apart, unclip the spade terminal on the wire leading to the bulb and remove the screw through the ring terminal with your smaller screwdriver. With that screw out and the wire detached, you can now remove the bulb assembly and store it away for the next time a bulb blows. Now cut the ring terminal off the end of the ground wire. You only need enough wire to crimp the spade terminal to, which was about 5/16" on mine. Strip off about half of the insulation and crimp on the 3/16" spade terminal. If the terminals are uninsulated or you are very concerned about shorts, you may wish to insulate the connection with electrical tape or heatshrink.
Now you can remove the factory foglight. The assembly is almost indentical to the Blazer light. Once again remove the side pieces, which are held on with T-15 Torx screws. Now that you can pull the light out of the housing, you'll see that the back is a bit different from the Blazer unit. There is a spade terminal built right into the back of the reflector for the ground connection, and the bulb assembly is held in with a spring clip. Remove the clip, bulb assembly, and ground wire from the reflector. I left the bulb attached to the wiring and reinstalled the new reflector right there. You also could unclip the bulb at the spade terminal in the wire, mount the bulb assembly into the reflector, then reattach the wire when the reflector is installed.
The final step is installing the new light. Though the retaining methods differ, the bulb assemblies are the same between the GM and Blazer lights. Secure the bulb assembly in the new reflector using the small screw through your modified ring terminal. Connect the new spade terminal to the truck's ground wire (make sure there's a good connection, and tighten the terminal a bit if needed) and reattach the wire to the bulb if you disconnected it when you removed the old light. (You could also just replace the female spade terminal on the factory ground wire with a ring terminal. I prefer my method, as you're not trying to attach the new connector on the relatively immobile wiring of the truck, and you're not cutting up your rare truck's wiring as well.) Wipe off the bulb just in case you got any contaminants (like oils from your skin) on it. Now put the new reflector and lens back in the housing and secure it with the side trim pieces. You can use either the Blazer Phillips screws or the GM Torx screws; I stuck with the Torx screws that had originally gone into the housing. The factory lens and reflector are sealed together (on mine at least), while the Blazers just have a rubber gasket. Be careful that the new lens doesn't fall while you're reassembling the light. Also note that the side pieces have alignment tabs that go inside the rear housing. If you don't get them inside, the lens will not be held tight, exposing the bulb to the elements and possibly allowing the new lens to fall out.
Make sure the new light works, repeat on the other side, and adjust the aim of the new lights (if necessary) while you've got your Torx driver handy. You're done! You should notice that the new foglights work much better. The original lights have a separate reflector piece in front of the bulb. This means that any light coming straight forward out of the bulb has to be reflected off two surfaces before it leaves the light. The new lenses' pattern also seems to work better, but that could be due at least partly to the age of my original lights.
Update November 1, 2001. Daron: "With the Blazer brand lights, you need to make sure the holes in the reflectors are up, otherwise the beam pattern will be high, and you wont be able to adjust the lights down. If you can find the Blazer brand "Diamond Blue" lights you will notice that the reflective cups are a direct replacement for ours, identical. You dont have to re-do the ground connector or re-adjust aim. They just pop in. The only deal with them is that the lens has a slight blue tint, easy to remedy if you dont dig the blue thing."
Update 2. After Daron mentioned it, I double checked my lights. I have the holes in my reflectors on the bottom, as did the other brand new ones at Wal-Mart. Perhaps this is model specific?
Bill "InvisiBill" Talcott
October 31, 2001