Since you mentioned you installed the 04 shifter and CDL, we will assume it is pre-04 car and did not come with it. There is a solenoid in the box that will prevent shifting to neutral if the key is out of the ignition. This thread may help:

https://www.landroversonly.com/forum...er-case-99601/

Also this: https://landroverforums.com/forum/di...e-70942/page2/

And this: https://landroverforums.com/forum/di...e-stuck-29750/

The solenoids are known to malfunction. You could have someone jumper the relay contacts while you are under the car and see if it clicks. You might even try jumpering it and see if it allows you to shift it. If you have a multi-meter you could test the contacts to see if the coil is open. Worst case you can remove it.

 

I just bench tested my spare solenoid, it is spring loaded down to prevent shifting without it being energized. Voltage causes it to move up, enabling shifting. If the circuit, relay, fuse, or solenoid are bad it will prevent shifting. As I said I would start at the fuse box by jumping the relay and see if you can get it to click and move to enable shifting too high, that way you don't have to get under the truck or take the console apart. Also if you have a multimeter you can check for resistance across the solenoid coil and if it is open you know you have either a broken wire or a bad solenoid. A bad solenoid will require that you remove the solenoid to be able to shift it.

 

This thread is a good example of why it's important on having your signature filled out with your vehicle specs.

99-02 do indeed have the interlock solenoid mounted on the TC and if it fails it is a major ordeal to get to and bypass (especially on the side of the road). Whenever I do a CDL upgrade on a 99-02 I highly recommend bypassing the stock TC mounted interlock solenoid and going with the 03-04 setup which is mounted externally on the 03-04 linkage.

If it fails you can access it without to much of a struggle from underneath vs a 99-02 setup which requires you to remove the drive shaft, ebrake assembly and if you were gifted with small hands you can remove it in about an hour since you'll be barely able to remove the 4 8mm bolts that secure it to the TC. Then you also have to remove a 10mm bolt that secures the Hi/Lo Shifter cable and with it in place it has a good deal of pressure on it & re-installing it can be fun.

 

This is why I eliminated the solenoid in the transfer case but kept the one at the lever
but if you have basic tools you can get at everything from the top

 

Andrew has an 03

 

I have an 03 with a 04 transfer case and CDL cable linkage. Will lost internet access this afternoon. Will check back again this evening. Then try to tear into the center console tomorrow

 

Okay you have an 03 you DO NOT have to gut the interior to push the interlock solenoid back on an 03-04 assembly. With two people (one inside the D2 & one under it) you can manually push the interlock solenoid back with a long long bladed flat blade screwdriver, or some other stiff long device of your choice. Removing the front drive shaft would certainly make the view easier, but it can be done without removing it (your choice). If you look up from below you will the 4Hi/N/4Lo shifter assembly. You will see the round area with a wire lead coming from it. Now on the other side is the linkage that goes forward & back. Between that linkage and the interlock you will see the tip of the interlock solenoid blocking the linkage from going forward & back. Simply reach up with something long & stiff (will probably regret saying that later lol....) and manually push it back while the person inside has the D2 in N with the parking brake applied they should be able to go from 4Lo past N and into the 4Hi position. Now you are out of 4Lo and can drive at regular highway speeds.

Or if it's freezing I guess you could gut the interior console, drill out 13 rivets, and manually manipulate the interlock solenoid from above.

 

Hey Andrew you are looking for a triangle shaped bit, I will try and get you a photo.

Get under the truck at the passenger door
Look up and rearward past the Double Cardan joint in the drive shaft
You should see the bits as in the image below That is mine in High

 

Way better image of mine in low range this only control Hi/Low not the diff lock - mine can be quite stiff to move from low. If you need more pictures or pictures of the neutral position let me know

 

I have a very detailed 3 line signature in the past. I am not sure why it not appearing> I appreciate you helping. Will look into signature issue when I return to civilization or Internet access