The Backstory
If you've been following along on this site, you know the 2018 Tacoma well. It carried our Alu-cab Canopy Camper coast to coast and nearly twenty MSO guided trips. In 2023, it was totaled. We hydrolocked it on a guided trip right on the border of West Virginia and Virginia. Jeff & Sheree towed us out of the trail and I burnt up the brakes descending the hill until we got to a gas station where we called the tow truck. After a long (and pretty painful) few months going back and forth with the insurance company, we came out on top and had enough left over to buy a 2021 Toyota Tundra. We named it Indy.
Why a Second Gen Tundra?
We went back and forth a lot between a second gen and a third gen, and it really came down to two things: 1) price and 2) the reliability of the 5.7L V8. The third gen moved to a twin-turbo V6, and I wasn't ready to give up the V8 on a truck we plan to take everywhere.
There were a few other things we really liked about the second gen. It has more space and more payload than the Tacoma, which gives us a lot more breathing room when planning out the build. I also love the simplicity of it. And this truck came with the 38-gallon gas tank, which was a huge plus because we'd talked for years about adding a long-range tank to the Tacoma. This one already had it. The leather seats were a nice upgrade, too (not exactly a build reason, but I'm not complaining).
This Time, It's an "Us" Build
I built the Tacoma mostly on my own. This time, Rachael is building it with me, and that's a big part of what this series is about. She loves the trips, the camping, and the community, but she's never felt all that confident out on the trail because she didn't have the knowledge or the skills to help if something went wrong. Her goal is to be able to at least contribute to a fix on the road, if not handle it herself.
So you'll notice I explain a lot of things in this series that I'd normally just do. If you're newer to wiring and wrenching, that's good news for you, too.
The Plan
We had a hard deadline: Indy's first Mountain State Overland guided trip at the end of March. The big stuff (suspension, wheels and tires, armor, and eventually the Alu-cab Modcap) would come later in the year. For now, the goal was simple: get the truck trail-ready, guided-trip-ready, and pup-ready.
The first couple of episodes in the series cover the smaller items:
Under-hood electrical panel and Switch Pros (this post)
Midland MXT575 GMRS radio (this post)
Snorkel
Diff breathers
Rear seat delete
I wanted to start with the electrical because it makes every other install easier. Once there's clean, fused power and a switch panel in place, adding a compressor, light bars, or the camper later on is just a matter of running a couple of wires to a known spot instead of going back to the battery every time.
The Power Tray & Switch Pros
The heart of this install is an under-hood mount from SDMT. It's similar to a power tray, and it sits right on top of the factory fuse box, which gives me one place to land just about everything.
Here's what's on it:
Blue Sea SafetyHub 150: This makes it really easy to hook up higher-draw accessories like the air compressor. It also has regular ATO fuse slots, so I wired the radio into one of those instead of running it through the Switch Pros.
120A breaker: This goes directly to the battery. Battery positive comes into the breaker, and power flows from there into the SafetyHub.
Negative bus bar: All of the accessory grounds land here, and it runs back to the battery.
Switch Pros power module: I pre-wired this on the bench and cut off a bunch of the extra leads I didn't need yet. As we add accessories, the positive leads go into the module and the negatives go to the bus bar.
So there are actually two separate circuits. One powers the SafetyHub and anything I want wired more or less straight to the battery (with a fuse in between, of course). The other powers the Switch Pros and everything I want to turn on and off from the cab. The compressor is a good example of both working together: it gets its power from the SafetyHub, and I switch it on and off with the Switch Pros.
Why Switch Pros?
Rachael asked me this on camera, and the biggest reason is physical buttons. I didn't want to rely on my phone or a touchscreen to turn things on and off, especially when I need to keep my eyes on the road. I want to be able to reach over, feel for the right switch, and hit it. Beyond the compressor, it'll run a couple of light bars and maybe some ditch lights down the road. There are also a lot of foundational pieces in the kit that make adding accessories later really simple.
The Switch Pros needs a few trigger wires from the truck:
Blue (ignition): Tells the panel the key is on. This goes to an ignition-switched fuse.
White (lights): Tells the switches to dim when the headlights are on. This goes to the low-beam headlight fuse on the right-hand side.
Pink (auxiliary): Not using it yet, so I coiled it up and tucked it away for later.
The Build
We started around 11 a.m. and worked the whole day. It took a lot longer than I expected (it always does), but here's how it went.
Mounting the Tray
The first thing I did was pull the battery. The tray sits basically right on top of the fuse box and has two legs. One bolts to an existing attachment point on the fuse box, and the other attaches to a point behind it. I did have to modify the rear bracket to clear a small electrical junction box back there.
At some point during all of this, I dropped a 10mm wrench somewhere in the engine bay. We spent the better part of an hour looking for it with the truck up on the floor jack. I guess it's not a driveway DIY if you don't lose a 10mm.
Tapping the Fuse Box
This was the most tedious part of the day. I needed to find an ignition-source fuse for the blue wire and the low-beam headlight fuse for the white wire. Rachael asked if we could get an "explain it to me like I'm five" section for this part, and honestly, I could have used one too.
Of course, the first add-a-fuse I had didn't match the prong style of the fuses in the box, so that was our first trip to the auto parts store. The one for the headlight ended up being a 15A. Lesson learned: check your fuse style before you start.
To get the trigger wires out of the fuse box, I drilled a small 5/16-inch hole in the top of the box and put a grommet in it. It's a small hole, so the grommet makes a pretty good seal. This was also the first time Rachael had seen me drill into the truck, which came with a quick lesson on what a center punch is for (it makes a little dimple so your drill bit doesn't wander). Then we painted the hole so it doesn't rust.
On the other end of the trigger wires, I put spade connectors so I can disconnect the whole panel if I ever need to remove it (more on that below). I cut down the Switch Pros side to length, crimped on the mating spades, and heat shrunk each connector. Once they were plugged together, we heat shrunk over the whole connection.
Power and Ground
With the triggers hooked up, I reinstalled the battery and ran the cables: positive from the battery to the 120A breaker feeding the SafetyHub, a separate lead to the Switch Pros, and the negative bus bar back to the battery. By the end of this step, all of the positive side was live and both circuits had power.
Installing the Midland MXT575
We ran the Midland MXT400 on the Tacoma, which at 40 watts was the most output you could get at the time. The MXT575 is its replacement. Midland has been great to us and to Mountain State for many years, and we use the radios a lot on our guided trips. We talk on the radio way more than people expect, and it's honestly one of the best parts of an MSO trip. It's how a group of strangers gets to know each other when we're not sitting around the campfire at night. It's such a big part of the experience that Paul and Bethany literally started a company around it.
The radio body mounts under the seat, and the wiring runs through the firewall and under the center console. To get there:
Pull the center console trim. Unscrew it, slide a trim tool under the panels, and pop them out. It's just a series of clips, and you won't break it.
Go through the factory firewall grommet. We opened a path with a trim tool and poked through the rubber. A coat hanger with a little WD-40 and electrical tape on the end works great as a fish tape.
Run the cable under the center console back to the radio.
Land power and ground under the hood. The positive goes to a fused terminal on the other side of the SafetyHub 150 (not one of the high-current studs), and the negative goes to the bus bar.
We had to modify the MXT575's power cable a bit for this install. By the end of the day we had power to the radio, but I still needed to order a few parts to finish it off.
The Switches
The best moment of the day was when the Switch Pros keypad lit up for the first time. I tried to get creative with hiding as much of the wiring as I could so the switches look like they came from the factory. Rachael also set her first rivnuts on this build.
Rachael's Takeaways
When I asked Rachael for her takeaway from the day, she said: "cut, strip, and crimp." She also said she liked seeing how a wiring harness goes through the firewall and how much of a clean install comes down to hiding the wires well.
What Would I Do Differently
The tray sitting on top of the factory fuse box has turned out to be a real pain. Every time I take Indy to the dealer for work, I have to uninstall the power tray so they can get to the fuse box. I'm glad I put spade connectors on the trigger wires (at least it unplugs cleanly), but if I were doing it again, I'd look for a mounting location or bracket that leaves the fuse box accessible.
I'd also map out every fuse I planned to tap and buy the right add-a-fuse taps before starting. That one step would have saved us a trip to the auto parts store and a good chunk of the day.
Tips, Tricks, and Resources
Protect all of your wiring from the elements. No exposed metal on any connection, and heat shrink everything.
Use wire sheathing anywhere a wire could move. On washboard dirt roads everything vibrates, and you don't want wires chafing on metal, aluminum, or anything hot.
Put a grommet in every hole you run wire through.
Paint any hole you drill so it doesn't rust.
Use spade connectors where the panel connects to the truck. You'll be glad you did when you need to pull it.
Get a magnetic telescoping pickup tool. You will drop a washer.
A coat hanger makes a great fish tape for pulling wires through the firewall.
Keep a spare 10mm around. You know why.
Parts List:
Electrical
SDMT under-hood power tray
Blue Sea SafetyHub 150
120A circuit breaker
Negative bus bar
Switch Pros switch panel (power module + keypad)
Midland MXT575 GMRS mobile radio
Add-a-fuse taps (15A for the headlight circuit)
Spade connectors
Heat shrink tubing
Wire sheathing
Grommets
Rivnuts
Tools
Socket set
Center punch
Drill and 5/16-inch bit
Rivnut tool
Wire strippers and crimping tool
Heat gun
Trim removal tools
Magnetic telescoping pickup tool
Coat hanger, WD-40, and electrical tape (for fishing wires)
Up Next
In Part 2, we drill into the fender and install the snorkel.
You can watch this whole episode, and the rest of the 10-part series, on the Mountain State Overland YouTube channel. The series is free to watch thanks to OK4WD, with additional support from Bilstein, Toyo Tires, Blue Ridge Overland Gear, GP Factor, and Midland. And if you want to see a build like this out on the trail, come join us on a Mountain State Overland guided trip!