JoeS

Been wanting to add an aux fuse box to handle my add-ons to keep the DIY vs OEM systems apart an

d neat runs. Hardest part was finding the spot for the homemade bracket as the fender well is loaded with components and tubing/ AC hose runs. Very pleased with the location, the fuse box choice, and how nice the wire runs turned out.

Went with a Home Depot steel 1" x 12" lumber strap. Was tough to hand bend as a vise would have been much easier. The aux box off of Ebay. There were two kinds- top or side mounted neg posts. Side posts for me was the only way to go as access was limited. Worked out great. Use 10 gauge silicon flexible wire for power and ground. More than enough for the distance and loads but will have no worries as all.

Only have the added engine bay 12 VDC socket, the rear 12 VDC socket, and the solar battery tender hooked up. Next is the powered sub to be mounted in the X-cab space under the shelf.

Hairyberry

I did similar to mine but mine is only running engine stuff at the moment because I did a 5vz swap and didn’t want to rely on all of the relays and fuses from 1992 and I also had to add a 7.5 amp fuse for the obd2 port. Also rather routing it to the battery I just pulled the 80 amp fuse out of the stock box and added a lug to it so now I have another layer of protection just in case something shorts out

2ToyGuy

I'm not being critical, but IMHO it would be better to run the aux fuse block directly off the battery. Why? Because the circuit the 80A breaker already protects has a specific draw. The 80A fusible link (Toyota calls it...it's a fuse) is designed to protect the circuitry it's in, and adding the aux fuse block can over-whelm the 80A fuse, if it has enough draw. It's much better to run the aux fuse block directly off the battery, with it's included fuse as shown in the pictures above to protect it. Also, if the aux fuse block should draw enough to burn the 80A fuse, the whole truck will be shut down, unable to run at all until the problem is fixed. If it's run directly off the battery, all that will be prevented from operating if there;s a problem is the stuff being run off the aux fuse block. The truck will continue to operate normally until whatever problem is burning the fuse protecting the aux fuse block is repaired.

Just my opinions, of course, but I spent my career life as a Radar Tech, and Lead Electronics Tech for an Aerostat Site. I did this stuff for a living...
Pat☺

JoeS

2ToyGuy........Thanks for the info. So direct connect the negative lead to the battery negative terminal? I can do that. Is that 80 AMP fuse arrangement specific to Toyota?

Noting will draw 80 amp, not even the new powered-sub at 15 to 20 amps. The fuses in the aux box are to be maxed at 30 amp. I am using 20 and 25 amps with a 40 amp in the positive cable. Not expecting use of multiple items nor high power items.

I am not very knowledgeable about electrical stuff. It baffles me. So, I turn to online and YouTube. There I read and saw dozens of 'How To,' but not a one mentioned how to ground he box properly like you. I appreciate the expert advice. I usually ask my Dad, an electronics design engineer, but he passed a few years back. I miss his help.

Good to have extra cable for fixes. Looks like more truck therapy tomorrow. Thanks again.

2ToyGuy

The ground cable can go direct to the fender/body metal, as long as the cable from the fender metal direct to the battery is in good shape. It's the positive that should be direct to the battery positive terminal.

Granted nothing in the aux box will draw 80A. HOWEVER! Will the aux box draw, PLUS the regular draw from the truck, be 80A or more? Will a short in one, or more, of the aux box circuits, plus the trucks max draw, draw more than 80A? Even for a short time? No pun intended. THAT's why it's best to connect the aux box positive (hot) directly to the battery hot (positive), not the 80A fuse. Does that make sense?

Pat☺

JoeS

Oh OK. That's how I have both now. I am using the same ground as the battery negative to the fender uses. Being OCD, I cleaned the battery wire connector on both sides, the fender contact to bare metal, and the threads on the securing bolt. It is a very clean and tight contact. The power lead is directly from the battery positive to the aux box positive connection. Again every thing was cleaned for good contact. I should be good. Thanks for the 80 amp load clarification- it's total from all sources.

Hairyberry

in my case I’ve been running my engine(3.4 swap) off of it it supplies the added on 200amp relays with power (overkill I know) and those relays turn the ecm on and power the injectors, coils and etc. so I felt that running it to the 80amp fuse wasn’t a bad idea as I also took a lot of load off of the stock EFI relay and now hooking directly onto the battery would require another 3 to 4 feet of wire to go across the core support as the battery is located on the drivers side now to make room for the air box on the passenger side. So in my mind hooking in to the 80 amp fuse either on the fused side or the not fused side was going to be my best bet because I could keep my wires short and close to the ecm and I don’t like unfused constant wires so I went to the fused side. I figure if I want to add something else into the fuse box I could just hook it up on the unfused side and put a mega fuse inline