Adding an Auxiliary Fuse Box

[meljr]

This is a write up of an easy do-it-yourself project that should not take more than 1 or 2 hours to complete. In fact, it took me longer to document it here than to do the project.

 

I seem to be doing a number of electrical modifications lately and auto electrical systems have always seemed like one of the dark arts to me. Maybe that is because of all the English Sports Cars I have owned had (have) Lucas electrical systems. After all, they don't call Sir Lucas the "Prince of Darkness" for nothing and do you know why the Brits drink warm beer? Its because they all have Lucas refrigerators :rotf: ; but I digress.

 

Anyway, I thought it might be somewhat helpful to share a few of the little electrical projects I have been doing in the hopes some of you may find the information useful, or maybe decide to take on a little wiring project. After all, if Mel can do it, you should have no problem at all. Please read this entire write-up before starting (especially the disclaimer at the end) and welcome to the virtual shade from the cedar trees in my driveway.

 

This first project is to add an auxiliary fuse box. With all of the specialty lighting, CBs, air compressors, winches, inverters and just plain accessories needing an electrical power source, tapping into your factory fuse box, which may already be old and near capacity, is just asking for trouble down the road, or off the road, for that matter. Any cracks I made about Lucas Electrical systems are just as applicable to Jeep/AMC/Renix systems, so adding extra, fused circuits is a project worth considering. Here is the solution I am implementing in my 1989 MJ Comanche, which is a close cousin to the Cherokee XJ series:

 

What is needed

• Fuse box with sufficient capacity (4-6 circuits would barely do it, 12 would cover just about any number of mods
  An in-line replaceable fuse capable of handing the combined load you anticipate adding to the new Fuse Box (carry a spare fuse)
  A cable heavy enough to handle the total anticipated load that is as short as possible to safely route from the fuse box to the positive (+) battery terminal
  A couple of ring terminal connectors for the positive (+) battery terminal and fuse box
  A butt splice of sufficient size to connect the in-line fuse to the cable between the battery and auxiliary fuse box
  Electrical tape and/or Heat Shrink tubing (preferred) and maybe some flexible automotive electrical conduit
  Wire ties and some miscellaneous hardware to secure the fuse box and cable run
  Common hand tools (e.g wrenches, socket set, screwdrivers and wire stripper/crimper and/or a heat gun for shrink tubing)
  A household, hand-held drill with an assortment of metal bits in case you need to drill a hole somewhere (I didn't)
  A soldering iron is optional; especially if you are a belt and suspenders kind of person.
  

 

Here, I have crimped and soldered a ring terminal on the in-line fuse holder. It is advisable to position the fuse as close to the power source (battery) as possible.

 

Now, I am test fitting the in-line fuse to the #4 cable that goes to the battery before crimping and soldering (in that order) the butt splice. The butt splice connectors (sample shown next to the actual connection) I purchased from the local NAPA store, already had solder inside, so I just had to heat both sides of the connection sufficiently to let the solder flow after crimping. Be sure your heat shrink tubing can be slid over the joint when you are done or otherwise insulate the connection prior to letting anything come into contact with the battery. Next, make up the ring terminal connection that will attach your cable assembly to the auxiliary fuse box.

 

Locate the fuse box in a reasonably safe place that is readily accessible, as you may need to get at it quickly and be able to visually inspect for blown fuses or loose connections under adverse conditions. I bolted mine to the bracket that holds the Renix Turtle for the cooling system on my MJ which is next to the firewall on the the passenger side. If I had to do it again, I would have purchased a weather resistant or water proof fuse box, readily available at a good marine supply store or on-line at a reasonable price. Note the green test fuse in the fuse box. The exposed connectors will not be "live" until you put a fuse in the associated position.

 

When the fuse box is secure, start installing the cable-fuse assembly by connecting the cable's ring terminal to the fuse box and routing the cable assembly carefully towards the positive (+) battery terminal.

 

Make sure your fuse is correctly installed in the in-line holder and then attach your cable-fuse assembly to the positive (+) battery terminal.

 

If you made it this far and passed the smoke/fire test, you can start installing accessory circuits from your new auxiliary fuse box. I will post an example of such a project in a few days. If you didn't pass the smoke test, the fuse should have saved you. If it didn't, don't call me as I disclaim responsibility for all acts of God or Humankind; call your insurance agent instead.

 

-mel

[Oddmodman]

I'm not criticizing, I just don't know. Umm, what's the point? If something goes out won't it just blow 2 fuses?

[Esgar]

I'm not criticizing, I just don't know. Umm, what's the point? If something goes out won't it just blow 2 fuses?

Reviving a deadish thread. The purpose of the main inline fuse before the secondary fuse block serves two purposes: 1: If the main lead going to the aux fuse block shorts out, it blows that fuse instead of burning the truck to the ground. 2: It's a double redundancy "failsafe" if you will. Say you've got offroad lights running off one of the fused terminals, and they overload the fuse, and for whatever reason, it doesn't pop like it's designed (Rare, but it happens), the fuse right at the battery blows, thus saving the truck from burning to the ground.

 

 

This is a write up of an easy do-it-yourself project that should not take more than 1 or 2 hours to complete. In fact, it took me longer to document it here than to do the project.

 

I seem to be doing a number of electrical modifications lately and auto electrical systems have always seemed like one of the dark arts to me. Maybe that is because of all the English Sports Cars I have owned had (have) Lucas electrical systems. After all, they don't call Sir Lucas the "Prince of Darkness" for nothing and do you know why the Brits drink warm beer? Its because they all have Lucas refrigerators :rotf: ; but I digress.

 

Anyway, I thought it might be somewhat helpful to share a few of the little electrical projects I have been doing in the hopes some of you may find the information useful, or maybe decide to take on a little wiring project. After all, if Mel can do it, you should have no problem at all. Please read this entire write-up before starting (especially the disclaimer at the end) and welcome to the virtual shade from the cedar trees in my driveway.

 

This first project is to add an auxiliary fuse box. With all of the specialty lighting, CBs, air compressors, winches, inverters and just plain accessories needing an electrical power source, tapping into your factory fuse box, which may already be old and near capacity, is just asking for trouble down the road, or off the road, for that matter. Any cracks I made about Lucas Electrical systems are just as applicable to Jeep/AMC/Renix systems, so adding extra, fused circuits is a project worth considering. Here is the solution I am implementing in my 1989 MJ Comanche, which is a close cousin to the Cherokee XJ series:

 

What is needed

Fuse box with sufficient capacity (4-6 circuits would barely do it, 12 would cover just about any number of mods

An in-line replaceable fuse capable of handing the combined load you anticipate adding to the new Fuse Box (carry a spare fuse)

A cable heavy enough to handle the total anticipated load that is as short as possible to safely route from the fuse box to the positive (+) battery terminal

A couple of ring terminal connectors for the positive (+) battery terminal and fuse box

A butt splice of sufficient size to connect the in-line fuse to the cable between the battery and auxiliary fuse box

Electrical tape and/or Heat Shrink tubing (preferred) and maybe some flexible automotive electrical conduit

Wire ties and some miscellaneous hardware to secure the fuse box and cable run

Common hand tools (e.g wrenches, socket set, screwdrivers and wire stripper/crimper and/or a heat gun for shrink tubing)

A household, hand-held drill with an assortment of metal bits in case you need to drill a hole somewhere (I didn't)

A soldering iron is optional; especially if you are a belt and suspenders kind of person.

 

Here, I have crimped and soldered a ring terminal on the in-line fuse holder. It is advisable to position the fuse as close to the power source (battery) as possible.

 

Now, I am test fitting the in-line fuse to the #4 cable that goes to the battery before crimping and soldering (in that order) the butt splice. The butt splice connectors (sample shown next to the actual connection) I purchased from the local NAPA store, already had solder inside, so I just had to heat both sides of the connection sufficiently to let the solder flow after crimping. Be sure your heat shrink tubing can be slid over the joint when you are done or otherwise insulate the connection prior to letting anything come into contact with the battery. Next, make up the ring terminal connection that will attach your cable assembly to the auxiliary fuse box.

 

Locate the fuse box in a reasonably safe place that is readily accessible, as you may need to get at it quickly and be able to visually inspect for blown fuses or loose connections under adverse conditions. I bolted mine to the bracket that holds the Renix Turtle for the cooling system on my MJ which is next to the firewall on the the passenger side. If I had to do it again, I would have purchased a weather resistant or water proof fuse box, readily available at a good marine supply store or on-line at a reasonable price. Note the green test fuse in the fuse box. The exposed connectors will not be "live" until you put a fuse in the associated position.

 

When the fuse box is secure, start installing the cable-fuse assembly by connecting the cable's ring terminal to the fuse box and routing the cable assembly carefully towards the positive (+) battery terminal.

 

Make sure your fuse is correctly installed in the in-line holder and then attach your cable-fuse assembly to the positive (+) battery terminal.

 

If you made it this far and passed the smoke/fire test, you can start installing accessory circuits from your new auxiliary fuse box. I will post an example of such a project in a few days. If you didn't pass the smoke test, the fuse should have saved you. If it didn't, don't call me as I disclaim responsibility for all acts of God or Humankind; call your insurance agent instead.

 

-mel

Nicely done, although, a little criticism, I think you should have put an extended piece of sheet metal and moved the block out away from the firewall, just due to the way the hinge swings, it's going to be fairly close to those contacts with the hood down. I'm definitely going to take your idea though and tweak it a bit for my truck.