3.7L V6 QT1 to QT2 Conversion.

I'm getting ready to install my NV245 transfercase into my XK. I have bench tested my program and controller for the last few weeks with excellent results. Very consistent results shifting the transfercase between all positions. Confidence is high that it will work. Only concern I have is throwing a Gear Ratio error code in Low or Low Loc position, which I will find out shortly, and I believe I have a fix for that if it occurs.
I am using the stock "T-Handle" transfercase switch, which will look stock. I Also have a power on "Key" to power on the controller and modules. My intent is for this controller to be completely off, with no power to it when driving "On Road". Off Road, you would power up and it would provide full manual control of the transfercase. Why not a simple linkage to shift, because this transfercase uses clutch packs to lock in high and low and requires the torque of the motor to apply pressure and hold it there with a brake.
Below is the way I see it operating, rough draft:


Transfercase Mode Selection.

Off Road Operation Only.

The procedure to shift (Select Mode Position) is as follows:

1. First turn on the power to the controller with the Keyed Power Switch by rotating it clockwise.

2. Press down on the vehicle’s brake pedal.

3. Shift the transmission into Neutral or Park.

4. Using a pen or other pointed tool, depress the Mode “Pen” Switch fully down and release. (This places the controller in the select mode) The “N” Indicator Light will light up solid to confirm the controller is in the select mode.

5. Next raise the Mode Select T-Handle up fully and down the number of times required for the Mode you desire to use.

• High Loc = 1 Count
• High = 2 Counts
• Neutral = 3 Counts
• Low = 4 Counts
• Low Loc = 5 Counts

6. After you have made your selection, depress the Mode “Pen” Switch fully down and release. This locks in your Mode Position Selection and powers the transfercase motor, which shifts the transfercase to your selected position.

7. Once the transfercase has been shifted, the “N” Indicator Light will flash the transfercase Mode Position.
“N” Indicator Light will flashes the following codes.

• High Loc = Light on, then off for 2 seconds
• High = Light on, Light off for a count of 2, then off for 2 seconds
• Neutral = Light on, Light off for a count of 3, then off for 2 seconds
• Low = Light on, Light off for a count of 4, then off for 2 seconds
• Low Loc = Light on, Light off for a count of 5, then off for 2 seconds

If you see a continuous rapidly flashing light, there is an error in the shifting of the transfercase. Please refer to the Error Code Section.

8. After the transfercase has completed the shift to your Mode Selection and you have confirmed the “N” Indicator Light has flashed the correct code, you may turn off the power to the controller with the Keyed Power Switch.

9. Shift your transmission back out of Neutral or Park .


Transfercase T-Switch Special Features

Off Road operation only.

With this controller for off road only, there is an option of leaving the power on while off road.
If you choose to leave the power on during off road use there are two additional features available.

These options are:

• High to High Loc toggle shifting (on the fly)
• Low to Low Loc toggle shifting (on the fly)

On these two options, it is not required to apply the brakes, place the transmission in Neutral or Park, nor depress the Mode “Pen” Switch to shift Mode Positions. This can be done, because the transfercase does not need to go across the neutral position of the transfercase to get to the other mode position.

1. The procedure is to raise the Mode Select T-Handle up fully and hold it up for 2 seconds, than lower it back down. If you were in High, the transfercase will be shifted to High Loc and vice versa. If you were in in Low Loc, the transfercase will be shifted to Low and vice versa.

2. After using the Mode Select T-Handle, always verify transfercase position by confirming the “N” Light is flashing correctly for the Mode Position selected.

This feature is very effective for negotiating tight trails. Example: Using Low to allow for easier turning and less wear on the drivetrain in easier and/or tighter turning areas, then when encountering a section requiring maximum traction, the Mode Select T-Handle can be used to toggle the transfercase into Low Loc. Once the section is completed, simply toggle the transfercase back to Low. Same example but only using High and High Loc as required.

Error Code Section

If the transfercase shift motor is unable to complete the selected Mode Position, the “N” Indicator Light will rapidly continuously. The main reason for this error to appear is when crossing over neutral the transfercase gears are not aligned properly to allow for complete engagement. What this means is the transfercase is stuck between positions.

The procedure to correct this error is:
1. Turn the power off to the controller with the Keyed Power Switch. Wait 5 seconds and turn the power back on, this will reset the controller error code.

2. Next use the Mode Select procedure to shift the transfercase back to the original Mode position.

3. Shift the vehicle into drive or reverse and move the vehicle slightly to re-phase the transfercase gears.

4. Then follow the Mode Select procedure to shift to the Mode Position you were selecting.

If this does not correct the problem after a few tries, then the other possible causes for this error are, no power to the transfercase motor brake or motor and/or a bad transfercase motor. See Troubleshooting electrical parts.



Why the power key, brake, neutral and Mode “Pen” Switch? It's to insure there is no unintended use or shift of the transfercase, unless you are completely aware of what you intend to do. Safety First.

That is awesome!!! I love the fact that because of people like you, we can all upgrade out jeeps to their full potential. Thanks, +rep fo' sho

Cant wait for you to get this installed! I wish I had the knowledge you have when it comes to stuff like this.

I mounted the controller under the dash just left of the steering column last night. I'll post some pics later this weekend And I'm making a panel that will go under the passenger side rear seat for the relays, sensor module and motor module. My idea is to keep all the electrical components inside the jeep. I should be able to start working on the wiring this next week, with the goal of installing the transfercase and being fully functional on the weekend of the 20th. Hoping for no Gear Ratio errors in Low or Low Loc. Reading the service manual, it could go either way. Best bet is I will need to shut off traction control, which makes the ARB rear locker and "manual" front ELSD more important.

Here is a picture of the controller mounted under the dash, just left of the steering column. No wiring to it yet.

To mount the Transfercase Select Switch, a couple holes need to be drilled on the bottom of the Shifter storage area. And a hole provide for the Switch Plug to plug into the rear of the Switch.
I think I can make a template for these holes.

Here is the Transfercase Selector Switch mounted and plugged into the stock wiring harness. My XK had this wiring in place. But it needs to be modified to work with my controller.

Here is the modified wiring, Pins 1, 2 & 3 cut and wired to run to my controller. Please note I have soldered and heat-shrink-ed all connections and sealed of cut ends of wiring harness that will not be used. I have run these wires along the stock wiring harness using tie-wraps. All changes under the console are complete.
Next will be making up the panel to mount the two modules and relays that will power and control the Transfercase Motor, that will be going in under the passenger side rear seat.
After that running the wires between the two areas, adding the key switch and testing the Transfercase before actually installing it. One step at a time.

Its looking good. Cant wait to see more pics!

Heck of a mod man!