I am looking to add some little lights to my tool boxes on the back of my truck. I wanted to run the power from the fuse box, so I bought an add-a-line fuse adapter, plugged it in to the radio fuse, and I cant get any voltage. I have tried it on several different fuses making sure that I had a good grounding point, and that the key was turned. I'm stumped. Any suggestions on how I can get the power back there? I wanted the lights to shut off when I took the key out just in case I forgot to shut them off by their built in switches.

 

Q1. Is this the type add-a-fuse you got ?



There are also the style that wraps onto the fuse that is in the fuse panel already, which I have not had much luck with ( others have with good results I guess, they have been around for years ).

Q2. When you tested power, was the key in the truck in the assy or run position ?

Q3. Did the radio work after installing the add-a-fuse ?

Q4. When you tested for power, did you have a good ground to use ( not just any screw is a ground wire ).

Q5. With this testing, were you using a 12+ tester or a meter ?

One option you have, if you have the factory tow package is to use the Battery circuit for the trailer. This is the Orange wire along the driver's side frame rail. This is a 12 AWG wire that is hot in the run position only.

This is also in the Connector 270N, on the pass side by the Central Junction Box ( this is red for 270E, 270 N is 4 connectors below it ).


This would make sure that you only have power when the key is in the Run position, and it is fed via the Battery Charge Relay and a 30 AMP fuse.

Just a thought on the topic, so you don't have to mess with the Add-a-fuse, or continue with using that, running it out of the cab of the truck.

 

Yep that’s exactly the ad-a-fuse I bought. Second I had the key in the assy position. Third no the radio did not work after installing the add-a-fuse. (maybe this is the problem?) 4th I did have a good ground because I used the large grounding connection under the fuse panel, I also ran a wire off the neg. terminal of the battery and used that as a ground just to be sure. 5th I tested with a meter which I know was working correctly because I tested it on the battery and got exactly 12 volts. I do like your idea of using the battery circuit wire. I think I might try that tomorrow. However the more I think about it the more I wonder if I should just make it always hot so I don’t have to mess around with putting my key in every time I want the lights on. I think I might install a lighted switch inside the cab that is hardwired to a always hot fuse. (that is... if I can find one)

 

That is strange, the first time I heard of that type add-a-fuse not working correctly. Never heard of an install in a '04+ MY truck until now.

Q1. Did you check the input power side of the add-a-fuse ?
- Thought is, it is not seating correctly in the holder, so if it is not getting power in, that would explain why the devices did not work. This is using your meter ( with the known good grounds you are using for testing, with the key in the assy position ) to check the one side ( don't recall which is power to the fuse ) or the other to see if +12 V is there.

The other option for the additional lamps could be to use the parking lamp circuit to activate a relay under the hood, and have the relay run a fused power lead from the battery to the tool box.
- Provides power to the lights only when the parking lamps are on ( relay coil activated by the parking lamp brown wire on the front parking lamp connector ).
- Would allow you to install say 14 AWG, and also have a power outlet back there in case ??

I don't like the always hot option, as I have a tendancy to forget things, and that woudl be it, dead battery for me.
If you are good with it, you could just run a new fused circuit from the battery into the cab with the correct contact rated switch ( i.e. 10 AMP, or what ever the lamps draw ) then back out to the tool box.

Either way, let us know which way you are going ( so the next member doing a search can find your solution ) , and if you need anything else on the topic.

Good luck.

 

Ok so first off I figured out what the problem was. The add-a-fuse I bought was crap. So I returned it, got a new one, and things went smoothly from there on. I ended up wiring the lights to a always hot fuse and putting a lighted switch next to my reverse sensing switch to control the lights. It works great. Thanks for your help sscully!


Lighted Switch



No flash photo to lighted toolbox



Flash Photo of lighted toolbox