I just did this yesterday for my 98 V6.
It was not too tough but the hardest part part for me was getting the correct Harness/Fuse Box.
I thought I'd Cross post this from the 3.8mustang Wiki.
I'll throw the Text here but you can go there for the Pics.
http://www.3.8mustang.com/wiki/Installing_Fog_Lights_%28DIY_and_OEM%29#OEM_Fog_Light_Installations_Overview
OEM Fog Light Installations Overview
The Main thing about adding OEM Fog Lights to your 3.8 is the Wiring. We all know GTs had it but I will show you what you you need to do to get OEM Fog Lights working on your 3.8 Stang. Unfortunately I can only confirm 94-98 Models but I am sure that the same Idea can be applied to 99-04 models as well. Take a Peak at your Local Wrecking yard and dig up some Fact Finding Comparisons to make sure. A good piece of advice to use is "The more things change, the more they stay the same."
94-Early 96
These years have the Fog light Sockets already installed. They are usually tucked away so peak around for them behind the Deletes. The connectors look like so:
After that just buy your Favorite USED, NOS or Aftermarket set WITH the Brackets and the Fog light Relay and Switch and Plug and play.
Late 96 to 97
You have 2 choices available to you, either:
1. Get a lighting harness from a 94-Early 96 mustang (any type). This Harness starts at the Fuse Box in the Engine Compartment and connects to the Light Sockets. It is one complete unit as seen in the picture Below.
Then just continue on as if you were a 94 to Early 96.
2. Find a GT Wiring Harness for your year. Replace as in Option 1. WARNING!! Make sure you replace the Fan Fuse with the Correct Relay for the 3.8. The GTs use a 60 Amp Fuse the 3.8 uses a 30A Relay.
98
98 Model users only have 1 OEM option available to them since the Fuse box is that of a 99-04 but the wiring is different than those years. Get a GT Wiring harness. Also WARNING!! Make sure you replace the Fan Fuse with the Correct Relay for the 3.8. The GTs use a 60 Amp Fuse the 3.8 uses a 30A Relay.
Installation Instructions
Installation instructions per year type.
For 94 to Early 96
Parts Needed
1x OEM Fog Light Switch for 94-00 Mustang
1x Pair of Fog Light Housings with Mounting Brackets
2x Fog Lamp Bulbs Model # 899
1x Fog Lamp Relay
1. Remove the Fog Light Delete Panels from the Fog Light cut outs in the Bumper cover.
2. Attach the Fog Light Lens Brackets into the Fog Light cut outs using the proper screws.
3. Insert Fog Light Bulb into the Lens and attach the Connector.
4. Insert the Correct Relay into the Engine Compartment Fuse Panel.
5. Remove Center Console from interior.
6. Detach the Fog Light Switch Plug from the Bottom of the Console. This is the Gray one. The Brown one is for the Convertible Top Switch.
7. Pop out the Coin Holder Closest to the Ash Tray. The 2 Coin Holder Deletes are keyed. One for the Convertible Top Switch the other for the Fog Light Switch.
8. Plug in the Switch and set into the hole.
For Late 96 to 98
Parts Needed
1x OEM Fog Light Switch for 94-00 Mustang
1x Pair of Fog Light Housings with Mounting Brackets
2x Fog Lamp Bulbs Model # 899
1x Fog Light Relay
1x Fuse Box Wiring Harness
Installation for the Fuse Box Harness is the same for all 3 years. 1. Remove the Head Lights and Marker Lights as per usual removal procedures.
2. Disconnect the White Connector connected to the firewall behind the Headlight and Marker Light. Bring the Light connectors up.
3. Disconnect the 2 Connectors located under the Air Filter Housing.
4. Remove the Radiator Brackets and the Reservoir Bracket. from the Core Support.
5. Remove the Battery from the Tray and Remove the Battery Tray.
6. On the underside of the Driver's Side Fender Well, Disconnect the Horn and Washer Fluid Tank and Unbolt the Washer Fluid Tank to provide easier Removal and Install of Wires in that area.
7. Unbolt the Wire Connector from the Fire Wall and Detach the Adjacent Connector.
8. Unclip the Fuse Box from the Mounting Bracket and remove the Harness from the car.
9. Install New Harness in reverse of directions above.
10. If Using a GT Harness NOW would be a good time to replace the 60 Amp Fuse with your 30 Amp Relay from your Old Harness. Also If your New Harness came with fuses already installed double check to make sure none are blown.
11. Remove the Fog Light Delete Panels from the Fog Light cut outs in the Bumper cover.
12. Attach the Fog Light Lens Brackets into the Fog Light cut outs using the proper screws.
13. Insert Fog Light Bulb into the Lens and attach the Connector.
14. Insert the Correct Relay into the Engine Compartment Fuse Panel.
15. Remove Center Console from interior.
16. Detach the Fog Light Switch Plug from the Bottom of the Console. This is the Gray one. The Brown one is for the Convertible Top Switch.
17. Pop out the Coin Holder Closest to the Ash Tray. The 2 Coin Holder Deletes are keyed. One for the Convertible Top Switch the other for the Fog Light Switch.
18. Plug in the Switch and set into the hole.
It was not too tough but the hardest part part for me was getting the correct Harness/Fuse Box.
I thought I'd Cross post this from the 3.8mustang Wiki.
I'll throw the Text here but you can go there for the Pics.
http://www.3.8mustang.com/wiki/Installing_Fog_Lights_%28DIY_and_OEM%29#OEM_Fog_Light_Installations_Overview
OEM Fog Light Installations Overview
The Main thing about adding OEM Fog Lights to your 3.8 is the Wiring. We all know GTs had it but I will show you what you you need to do to get OEM Fog Lights working on your 3.8 Stang. Unfortunately I can only confirm 94-98 Models but I am sure that the same Idea can be applied to 99-04 models as well. Take a Peak at your Local Wrecking yard and dig up some Fact Finding Comparisons to make sure. A good piece of advice to use is "The more things change, the more they stay the same."
94-Early 96
These years have the Fog light Sockets already installed. They are usually tucked away so peak around for them behind the Deletes. The connectors look like so:
After that just buy your Favorite USED, NOS or Aftermarket set WITH the Brackets and the Fog light Relay and Switch and Plug and play.
Late 96 to 97
You have 2 choices available to you, either:
1. Get a lighting harness from a 94-Early 96 mustang (any type). This Harness starts at the Fuse Box in the Engine Compartment and connects to the Light Sockets. It is one complete unit as seen in the picture Below.
Then just continue on as if you were a 94 to Early 96.
2. Find a GT Wiring Harness for your year. Replace as in Option 1. WARNING!! Make sure you replace the Fan Fuse with the Correct Relay for the 3.8. The GTs use a 60 Amp Fuse the 3.8 uses a 30A Relay.
98
98 Model users only have 1 OEM option available to them since the Fuse box is that of a 99-04 but the wiring is different than those years. Get a GT Wiring harness. Also WARNING!! Make sure you replace the Fan Fuse with the Correct Relay for the 3.8. The GTs use a 60 Amp Fuse the 3.8 uses a 30A Relay.
Installation Instructions
Installation instructions per year type.
For 94 to Early 96
Parts Needed
1x OEM Fog Light Switch for 94-00 Mustang
1x Pair of Fog Light Housings with Mounting Brackets
2x Fog Lamp Bulbs Model # 899
1x Fog Lamp Relay
1. Remove the Fog Light Delete Panels from the Fog Light cut outs in the Bumper cover.
2. Attach the Fog Light Lens Brackets into the Fog Light cut outs using the proper screws.
3. Insert Fog Light Bulb into the Lens and attach the Connector.
4. Insert the Correct Relay into the Engine Compartment Fuse Panel.
5. Remove Center Console from interior.
6. Detach the Fog Light Switch Plug from the Bottom of the Console. This is the Gray one. The Brown one is for the Convertible Top Switch.
7. Pop out the Coin Holder Closest to the Ash Tray. The 2 Coin Holder Deletes are keyed. One for the Convertible Top Switch the other for the Fog Light Switch.
8. Plug in the Switch and set into the hole.
For Late 96 to 98
Parts Needed
1x OEM Fog Light Switch for 94-00 Mustang
1x Pair of Fog Light Housings with Mounting Brackets
2x Fog Lamp Bulbs Model # 899
1x Fog Light Relay
1x Fuse Box Wiring Harness
Installation for the Fuse Box Harness is the same for all 3 years. 1. Remove the Head Lights and Marker Lights as per usual removal procedures.
2. Disconnect the White Connector connected to the firewall behind the Headlight and Marker Light. Bring the Light connectors up.
3. Disconnect the 2 Connectors located under the Air Filter Housing.
4. Remove the Radiator Brackets and the Reservoir Bracket. from the Core Support.
5. Remove the Battery from the Tray and Remove the Battery Tray.
6. On the underside of the Driver's Side Fender Well, Disconnect the Horn and Washer Fluid Tank and Unbolt the Washer Fluid Tank to provide easier Removal and Install of Wires in that area.
7. Unbolt the Wire Connector from the Fire Wall and Detach the Adjacent Connector.
8. Unclip the Fuse Box from the Mounting Bracket and remove the Harness from the car.
9. Install New Harness in reverse of directions above.
10. If Using a GT Harness NOW would be a good time to replace the 60 Amp Fuse with your 30 Amp Relay from your Old Harness. Also If your New Harness came with fuses already installed double check to make sure none are blown.
11. Remove the Fog Light Delete Panels from the Fog Light cut outs in the Bumper cover.
12. Attach the Fog Light Lens Brackets into the Fog Light cut outs using the proper screws.
13. Insert Fog Light Bulb into the Lens and attach the Connector.
14. Insert the Correct Relay into the Engine Compartment Fuse Panel.
15. Remove Center Console from interior.
16. Detach the Fog Light Switch Plug from the Bottom of the Console. This is the Gray one. The Brown one is for the Convertible Top Switch.
17. Pop out the Coin Holder Closest to the Ash Tray. The 2 Coin Holder Deletes are keyed. One for the Convertible Top Switch the other for the Fog Light Switch.
18. Plug in the Switch and set into the hole.
