E-Locker Retrofit in a 1999 4Runner

Parts you’ll need:

• E-locked third member (with matching gear ratios as your front differential)
  
  
• E-locker axle housing (or modify a none e-locker axle housing like I did)
  
  
• 4WD ECU with pigtail (This controls the e-locker) Part # 89533-35070
  
  
• E-locker switch with pigtail Part # 84725-35010
  
  
• 25 ft approximately of 16 AWG wire (7 different wires, 6 different colors, two are just a ground)
  
  
• Female connector (this connects to the OEM wiring harness by the gas tank) Part # 90980-10897
  
  
• OEM wiring harness (This runs from the gas tank down to the axle, this contains the connections to the actuator and the position sensor as well as the breather hose) Part # 82127-35100
  
  
• Yotamasters E-locker retrofit kit (If you’re not using an e-locker housing)
  
  
• Repair wire with female terminal (allows the dash indicator to light up) Part # 82998-24180
  

I originally bought an e-locker axle housing, but later found out that it was bent. Which was a bummer because I wasn’t able to return it and it would’ve been way easier because it required no extra modification to the housing. I went back to the junkyard and found a straight axle housing, but it wouldn’t fit an e-locker so it required extra work to make everything fit. I also took the time to repaint the axle and rebuild it with new bearings, seals, and brakes. I also reinforced it with a BARNES 4WD Heavy-Duty Diff Cover and a Freel Good Performance Bash Plate, as well as a Low Range Off-Road actuator skid plate. I originally wanted to go with Marlin Crawlers Diff Cover, but as per usual, it was sold out. In the end, I’m glad I went with BARNES because it seems to be more heavy-duty and was the same price.

The first thing I did was cut off the differential cover. This made it easier to drill the holes needed for the e-locker third member. Using the template included in the Yotamasters kit, trace out where you need to cut for the e-locker actuator fork. Make sure not to cut too much, there isn’t much room left on the mating surface for a good seal. One possible remedy is to weld a few beads around the edge of the mating surface on the right side, then grind flat. This provides more surface area and should help seal the differential better. I didn’t do this, so hopefully my seal holds. There are several stud holes in the axle housing that you won’t need when swapping over to an e-locker. However, you will need to drill and tap 4 new holes for the studs. The Yotamasters kit also provides a drill and tap for this job. It’s extremely important when drilling that you are square to the mating surface or else the third member won’t slide on. I used a special V-Drill guide that helps keep my drill bit perpendicular to the surface. This made it much easier for me to accomplish this job. This is why cutting off the differential cover was beneficial because it allowed me to clamp the V-Drill guide to the axle housing so it wouldn’t move. Installing the third member is also a good idea when drilling the first bit of the holes. It allows your drill bit to drill in the exact spot it needs to and eliminates the guesswork. After all the holes are drilled, you can now tap the new threads. You’ll need an M8x1.25 tap in case you didn’t buy it from Yotamasters. Thread in all the studs and do a quick test fit, this is when you find out if you drilled the holes correctly! If you aren’t replacing the differential cover, you may experience fitment issues with the third member hitting the factory diff cover. You may need to use a hammer and drift to allow more clearance for the third member. Again, I didn’t have to do this because I used an aftermarket diff cover. You also won’t run into this issue if you are using an e-locker axle housing.

After you are done with these steps, the third member should drop into the housing with no problem, now all that’s left is wiring! Yaayyy… When I went to the junkyard, I also grabbed the pigtails and connectors that are under the driver’s rear seat by the fuel pump. I used these because it provides a more factory look, and if you ever need to disconnect the wiring for whatever reason, you can do that just as if it came from the factory. Timmy The Toolman provides a nice video on the wiring needed to complete this job. In that video, they used trailer wire instead of individual wires like I did. Trailer wire is easier because they are all bunched together in a neat bundle and protects the wire more. I decided to use individual wire because I couldn’t spare the room. It’s a tight fit as is and I already have an auxiliary power wire running along the body. You can also choose whether to crimp or solder the connections. I chose to crimp for a couple of reasons. Crimping is way faster when you’re having to make 20 different connections, and in my opinion, it’s also a more reliable connection. If for some reason you didn’t wire your circuit correctly, the wire could overheat and actually melt the solder away, destroying the connection. With a crimp, even if that wire overheats, it will maintain the connection. You can also choose to use a tap-a-fuse or hard-wire the power wire into the car. Tap-a-fuses are nice because of how fast it can be to tap into a circuit. I wanted a more OEM look, so I chose to hard-wire my connection. It certainly takes more time, but I thought it was worth it not having to see an ugly tap-a-fuse in my fuse box. You need to locate a 12V power wire coming out from the back of the fuse box under the driver-side dash. You’ll also need to use a 10-amp inline fuse. I used what is called a T-splice to make these connections, it’s a much more reliable type of connection that doesn’t compromise the factory wiring like a T-Tap.

The diagram below shows you all the wiring that is needed to complete this mod. It’s really quite easy to follow and only requires a basic understanding of wiring. Timmy The Toolman’s video is also a huge help. The only issue I ran into was the female plug that connects to the OEM diff lock wiring harness diagram was incorrect. Either the diagram I was using was inaccurate or the OEM wiring harness I bought from Toyota was incorrect. Whatever it was, it really doesn’t matter all that much because you can always change the location of the wires that go into the female plug by depinning them. In my circumstance, I had to flip the top row of wires with the bottom row of wires. To further elaborate, pin location 8 changed locations with 4, 7 changed locations with 3, 6 changed locations with 2, and 5 changed locations with 1. This was what I had to do to make my connections work, but yours may be different. To make sure yours are correct, just match up the wire colors. They should be the same colors, just slightly off-shade or the wire stripe and solid wire are swapped.

Once the wiring is done everything should work. One thing to keep in mind is when installing the third member, make sure it’s in the locked position. Also, before you plug the connectors into the actuator, make sure the e-locker button is pressed in. I didn’t do this and the e-locker wouldn’t engage, so don’t make the same mistake! I hope this write up and pictures help, if you have any questions do hesitate to ask!