Acura TL 2004-2008: How to Wire Independent Fog Lights
Why live with the tyranny of the factory headlight switch dictating when you can use your fog lights? This article will show you how to rewire the factory fog lights so that they work separately from the headlights.
This article applies to the 3rd Gen Acura TL (2004-2008).
Fog lights are a great feature, but what's the point in having them if you can't use them separately from the head lights. The 3rd gen Acura TL doesn't give you direct control over your fog lights, so if you want them to work independently, you'll have to do a bit of work. Fortunately, it's a fairly simple procedure.
Materials Needed
- 16 gauge and 12 gauge wire
- Inline fuse holder with 10 amp fuse
- Soft pry tool
- Wire stripper
- Soldering iron and solder
- Electrical tape and heat shrink
- Coat hanger
- Razor
- Zip ties
- Multimeter
Before you start this project, you need to do a bit of planning. You need to find a switched 12 volt power source to tap into, otherwise the fog lights will stay on even when the car is off. You can find one by checking wires with a multimeter. A good source is the power wire for the windshield wipers. Once you've found a source, mark it, then disconnect the battery so you don't risk a short circuit.
Step 1 – Remove the steering column covers
Pry off the lower dash panel next to your steering column. Then remove the three screws on the opposite sides of the steering wheel column. Pry the two cover halves apart, then remove them from the steering column.
Figure 1. Pry off the lower dash panel. 
Figure 2. Remove the steering column covers.
Pro Tip
Be careful removing the plastic covers, as it is very easy to break the clips that hold them to the steering column.
Step 2 – Rewire the combination switch
Locate the wiring harness for the combination switch. Push in the tab and disconnect the electrical plug. In the bundle of wires, find the blue and white wire that goes to the fog light relay. Cut that wire and solder a length of 16 gauge wire to the side that goes to the connector. Wrap the splice in electrical tape. Then reconnect the wiring harness plug to the combination switch.
Step 3 – Route wire through firewall
Take your long 16 gauge wire down to where the main factory wiring harness goes through the firewall. Next to the large wiring harness there should be a cap you can remove to create an opening. Replace the cap with a grommet, or make a hole in it for the wire, and pass the wire through the firewall. Continue routing the wire through the engine bay to the small relay box next to the main fuse box.
Step 4 – Rewire fog light relay
Remove the top and bottom covers to the small black box, then disconnect the wiring harness. Locate the small blue and black wire on the wiring harness. Cut this wire and solder your new wire to the end of the wire going to the relay. Wrap the connection in electrical tape.
Figure 5. Disconnect wire harness from the black relay box. 
Figure 6. Rewire the small black and blue wire.
Step 5 – Tap into accessory wire
On the same wiring harness going to the relay, locate a large red and blue wire next to the wire you just sliced into. Cut this wire and solder on a smaller length of 12 gauge wire, then reconnect the wiring harness. Route this 12 gauge wire to the 12v power wire you found before you started. Strip off a section of the accessory wire cover and connect your inline fuse holder to it, then connect your 12 gauge wire to the inline fuse holder. Wrap the connections in electrical tape. Insert the 10 amp fuse in the inline connector and you are done.
Reconnect the battery and test the fog lights. They should now come on independently from the headlights.
Figure 7. Rewire the large blue and red wire. 
Figure 8. Solder inline fuse holder to accessory wire. 
Figure 9. Solder 12 gauge wire to inline fuse holder.
Related Discussions
- DIY Independent Fog Lights with Stock Switch - AcuraZine.com
- Acura TL wiring Diagram - AcuraZine.com
