I thought I would update this thread now that I have been through this just in case it helps anyone in the future. Here are some notes.
I had to make several phone calls to TCI to try to figure out how to make this work. I was disappointed in the level of support I got. First off, as I explained what I was working on, the guy said that the EZ-TCU was not designed for a 4x4. I did a lot of research on their site and not once did I find anywhere that stated it was not designed for a 4x4. Second, they said I could make it work but would have to buy more components to do that from Dakota Digital. However, when I asked what the components were, they couldn’t tell me. They just said “call Dakota Digital (DD)” and they can help you.
It did take a few phone calls to DD to explain what I was trying to do but we got it figured out. I listed the parts below. I did have to call them a couple of times for support because their controller wasn’t just plug and play, it took some cyphering. But, they were much more helpful than TCI.
Personally, after all this I’d recommend looking at another controller. Maybe they are all similar in that they need extra components to make them work. I really only looked at TCI because it “seemed” like a simple plug and play.
A little background, I have a M998 that had the 6.2 and the 3 speed trans. I’ve had it for several years and while it is great to drive around under 40 mph, anything above that it was not so I decided to make it a little more drivable, I wanted to upgrade to the 6.5TD and 4L80E. I won an auction for a 6.5TD and worked on it over the summer. I have a friend that has a transmission shop so I was going to let him do the transmission since he was set up for it. He did the trans install and then I did the EZ-TCU install and programming.
The EZ-TCU needs at a minimum a good RPM signal, a speed signal and TPS signal. I used the crank position sensor on the 6.5TD with a little help from Mogman (thanks). One wire needs to be grounded at the same location the EZ-TCU gets grounded and the other goes to one of the RPM wires on the TCU harness (there are two, doesn’t matter which you use). I got a reliable 650-700 signal at idol.
Here’s where it gets tricky, the speed signal has to come off the transfer case. My speedo cable was already broken and didn’t work so I opted to just remove it and install a GPS speedo. So, I removed the cable and the 90 at the transfer case and installed a DD pulse generator. The pulse generator has two wires that get ran to the DD controller and landed on the SPD Input and SPD- terminals. The OUTPUT SHAFT SPEED harness on the TCU needs to have the plugin cut off and then the wire with the stripe goes to ground and the other goes to output 3 on the DD controller.
The TCU has a setup you have to go through, to get the correct speed to show up on the TCU, you have to calculate your differential ratio and your geared hubs. In my case, I have 2.56 as Coug (thanks) mentions above and geared hubs are 1.92 so I entered 4.92 as my gear ration. This puts the speed on the TCU within 1-2 MPH of my GPS speedo. If you don’t put the right ratio, this really messes up your speed on the TCU. TCI will tell you that you only need your differential ratio but I suspect they had no clue what I was talking about with geared hubs.
The rest of the setup on the TCU is pretty self explanatory. I have my TC lockup set at 50 and at 60 I’m running 1800 RPM with 40” tires.
Additional Dakota Digital parts needed:
SGI-100BT -
Universal Speedometer and Tachometer Interface (has an app that makes it much easier to set up than using the interface on the controller itself.
SEN-01-4160 -
Speedometer 8K Pulse Generator (this has the passthrough for your speedo cable if you plan on keeping it)
SEN-01-1 -
8K Pulse Generator (this is what I used in place of speedo cable)
Here are the settings I used on the SGI-100BT:
Here are some of the settings I used in the EZ-TCU:
Tire Diameter and Gear ratio are the important ones, the others you can adjust to your desired performance
In the Setup Wizard
Tire Diameter: 40 (set this to your tire size)
Gear Ratio: 4.92 ( Diff Gear Ratio multiplied by 1.92 for geared hubs)
Max Shift RPM: 2850rpm
Lowspeed Shift: 9
Shift Aggress: 2
Shift Firmness: 5 (If it shifts too hard adjust this between 0 and 5)
Min TCC lock MPH: 50
Max TCC TPS: 70%
I hope this helps save someone from the frustrations that I experienced the last couple of weeks.
