DIY: Wiring after-market lights

Questions related to the wiring of after-market lights seem to be an on-going topic. Toy4Life was specifically asking how to wire them so they go off with the ignition. So, hopefully this write-up will serve as instructions for him and others in the future.

This is a detailed step-by-step of how I wired my pair of Pro Comp 100W off-road lights on my 2007 Tacoma TRD. I have a single switch on the dash that controls both off-road lights. The lights can be turned on/off at any time. They are not tied into my regular headlights or fog lights at all. The lights automatically go off when the ignition is turned off. I use a relay to control the power to the lights. Using a relay makes the job more complicated but it is a safer method. Using a relay also allows you to use a smaller switch because the switch does not have to carry the full electrical load of the lights. The switch circuit is separate from the light circuit. If you want to know more about relays check out this site (http://www.the12volt.com/relays/relays.asp). This method should work fine for any combination of lights as long as the total wattage of all lights is 240W or less.

If all of your lights are rated more than 240W in total, you will have to use a larger inline fuse and heavier gauge wire than what I have specified below. Fuses are usually rated by the amount of amps they can handle. You can figure the amp draw of your lights by dividing the total wattage of your lights by 12 (volts). So, if your lights total 300W you would need an inline fuse capable of carrying 300w/12v, or 25 amps. You would also need to use heavier wire, at least 12 gauge. The smaller the wire gauge number, the heavier the wire. The heavier the wire, the more electricity it can safely carry. It doesn’t hurt to use too big a wire but it is dangerous to use too small a wire. If your total amp draw is greater than 30 you will also need a heavier relay than the one I specify below.

As you run your wires, try to keep them out of the way and protected. Use plenty of wire ties. You will be instructed to connect a few wires to a good ground. A good ground is anything metal that is bolted or screwed to the frame, which is ultimately connected to the negative terminal of the battery. If the surface is painted be sure to scrape off the paint so the ground wire is touching bare metal.

With the exception of the lights, you should be able to find all of the necessary items at your local auto parts store or Radio Shack. The links provided in the Items List section are simply so you can see what I am talking about. I have not dealt with any of the web sites listed.

 

Relays
Relays have several connectors on the bottom. Each connector is usually marked with a number as shown below. I will reference these numbers when I instruct you to connect a wire to the relay.



Picture of relay


Bottom view of relay

Fuse Taps
Fuse taps allow you to tap into the power connections on a fuse panel. In this case we are going to use a connection that is normally unused. There are a few different kinds of fuse taps. I prefer the type shown below because it has the fuse built-in.

 

Items List
- After-market lights rated at approx 200W in total
- (1) 12vDC SPDT relay at rated 30 amps (similar to http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=330-070)
- 14 gauge wire
- 22 gauge wire
- Crimp-on female spade connectors for 14 gauge wire (preferably the type with a covering over the metal part)
- Crimp-on female spade connectors for 22 gauge wire (preferably the type with a covering over the metal part)
- Crimp-on ring connectors for 14 gauge wire (similar to http://www.mpja.com/viewallpict.asp?dept=319)
- (1) 20 amp automotive inline fuse
- (1) switch for the dash (lighted or not)
- (1) mini fuse tap (similar to http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=071-585)
- (1) 1 or 2 amp fuse to fit the fuse tap
- Plastic wire loom tubing (similar to http://www.crowbarelectricalparts.com/Loom_and_Spiral_Wrap.htm)
- Wire ties
- Electrical tape
- A crimp connector tool
- Wire cutters
- Voltmeter

 

Step-By-Step Wiring Instructions

1. Mount the lights on your truck

2. Mount the relay in the engine compartment. I mounted my relay to one of the screws that hold on the horn, as shown below. In this picture you can also see where I ran the 2 blue wires through the firewall (we will get to that later). You can also see that I used the horn mounting screw on the right for my ground connections.

 

3. Mount the switch on the dash somewhere. The picture below shows where I mounted mine. I simply drilled out the center of an unused switch blank. I made the hole slightly smaller than the diameter of the switch mount so it fits very tightly into the hole. I like this switch because it lights up when the lights are on and it matches my Speedway Blue. These switch blanks simply pop out. If you remove the fuse panel cover (the door shown right below the switch) you can reach up through the fuse panel opening and push the blanks out. The second picture shows the switch after I popped it out. This switch is also easy to wire because you can simply use spade connectors.

 

4. If you are not using a lighted switch skip this step. If you are using a lighted switch it will have a ground connection on it. Cut a length of 22 gauge wire to reach from the switch to a good ground. Connect one end of the wire to the ground connector on the switch. Connect the other end of the wire to a good ground on the truck. I ran my ground wire through the firewall to the horn mount as shown in the picture above.

5. Cut a length of 22 gauge wire to reach from the relay to the switch on the dash. You can run the wire through the firewall right next to the steering column. There is already a large group of wires running through the firewall at that location. I used a wire clothes hanger to get it through the rubber. Put a spade connector on the wire in the engine compartment and connect it to the relay post marked 86. Connect the other end of the wire to one side of the switch on the dash (it doesn’t matter which side). How you connect the wire to the switch will depend on the type of switch you have. Some of them accept spade connectors, some of them may require soldering.

6. Cut a length of 22 gauge wire long enough to go from the relay to a good ground in the engine compartment. Put a spade connector on one end of the wire and plug it into the relay post marked 85. Connect the other end of the wire to a good ground. Again, I used the horn mount screw.

7. Cut a 6 inch length of 14 gauge wire. Put a spade connector on one end of the wire and connect it to the relay post marked 30. Connect the other end to one side of the 20A inline fuse.

8. Cut a length of 14 gauge wire long enough to go from the opposite end of the inline fuse to the battery. Connect one end of the wire to the opposite end of the inline fuse. Connect the other end of the wire to the positive battery post.

9. Cut another length of 14 gauge wire long enough to go from the relay to your off-road lights. Put a spade connector on one end of the wire and plug it into the relay post marked 87 (NOT the one marked 87a). Connect the other end of this wire to the black wires of BOTH off-road lights.

10. Cut another length of 14 gauge wire long enough to go from the off-road lights to a good ground somewhere near the lights. Connect one end of the wire to the white wires of BOTH off-road lights. Connect the other end of this wire to a good ground nearby.

 

11. Find an open (unused) fuse slot in your interior fuse block that is tied in with the ignition switch (see picture below for the one I used). You can find this by using a voltmeter. Set the voltmeter to the 12V DC setting. Connect the black voltmeter cable to a good ground near the fuse block. Turn the truck ignition to the on position. Using the red voltmeter cable, touch the open (unused) fuse slot and see if you get a voltage reading on the meter. If you don’t, then go to the next open slot and test it. Once you find a unused slot with power, turn off the ignition switch and test the same slot again. If you still have power, repeat these steps on the next open slot. You want to find a slot that has power when the ignition is on, but does not have power when the ignition is off. As shown in the picture below, I used the second fuse slot from the left, on the next to last row of fuses.




12. If you are plugging the fuse tap into a fuse slot that is currently being used, remove the existing fuse and plug it into the fuse tap slot nearest the metal plug-in. Plug the new 1 or 2 amp fuse into the fuse tap slot farthest from the metal plug-in. Since I used an empty fuse slot in the fuse block, you can see the single small fuse plugged into the fuse tap in the picture below. Plug the fuse tap into the fuse block slot identified in the previous step.

13. Cut another length of 22 gauge wire long enough to go from the fuse tap to the switch on the dash. Connect one end of the wire to the crimp connector on the fuse tap. Connect the other end of the wire to the unwired connection on the switch. In the picture above you can see the blue crimp connector that is connecting the red fuse tap wire to the blue wire running to the switch. The picture below shows the fuse tap unplugged from the fuse panel.

 

14. WooHoo! That’s it. Test your handywork for proper operation.

15. Once you know it is working correctly, clean up your wiring runs by securing the wiring with plenty of wire ties. You can also use the plastic wire loom tubing to protect exposed wires, especially in the front of the truck where they might be exposed to road debris, snow, or off-road snags. You can wrap the wire loom with electrical tape to keep the wires from coming out of the loom. This makes for a much more professional looking job. The picture below is looking at the underside of the front of my truck. You can see the wire loom protecting the wires as they run from the lights to the inside of the engine compartment.

 

Thank you rhoppas. I don't think you could've been more detailed, specific, and clear. Excellent right up. If this is not a sticky, it should be.

 

Thanks guys...I appreciate it!

 

I think I'll add a link in the Cheap/free mod section so people doing any of the lighting mods can reference it if needed.

 

Nice looking job! Gives me motivation to change out that cheesy looking switch that came on the wiring harness with my lights.

 

I know what you mean. The switches that come with the lights are usually big and ugly (cheap). You can do so much better with just a few dollars and a little effort. There are hundreds of choices between the Internet and your local auto parts stores. Or you can get a stock switch from Toyota.

 

Here is a picture of the fuse block of a 1st gen truck (2002) with the add-a-circuit. I used the top slot (empty) on the far left column. Note: My add-a-circuit would not work without 2 fuses installed. I used a 5 and a 7.5

 

Congrats on getting your lights wired up. I forgot you had a 1st gen. That's great. Now we have both gens covered in the tutorial. Strange that you couldn't get the Add-A-Circuit to work without both fuses.

 

The only install differences were the fuse box and the location for the switch.

 

Do a search on Ebay, I picked up OEM Toyota foglight switches for about $20. Nice.

 

these in dash switches are nice and affordable at 7 dollars a piece. just bought two. http://www.rallylights.com/hella/switches_illuminated_rocker.asp

 

I think the second set of switches are the ones I used in this guide (HL80565 Blue). I am not 100% sure, but it sure looks like it. Thanks for the post.