Fixing Stuck CDL

[Joey]

Chances are if you are reading this you bought a used Series One Land Rover Discovery and have spent countless hours reading your owner’s manual, searching the web for answers, and trying every combination of transmission in drive, transmission in neutral, going over 5 M.P.H. going under 5 M.P.H., emergency brake on, etc. and you have finally come to the conclusion that your differential lock is thoroughly stuck. This page will hopefully provide you with guidance into fixing this common problem on Land Rover Discoveries.
The problem with Land Rovers, if you can consider this a problem, is that they need to be used for what they are designed to do. If you go through most of your Disco ownership wondering what that funny handle is in front of your shifter, when you actually find out what it is and decide to use it, it won’t work. While abuse of the diff lock, such as engaging it at 50 M.P.H. on a curvy highway exit ramp, will reduce the transfer case to a pile of metal that sounds like ball bearings in a washing machine, you shouldn’t be afraid or *gasp* feel guilty using it. Perhaps the mechanism has a flaw that skipped over the engineers in Solihull, but simply giving a working lever a nudge every month can prevent this problem from ever occurring.
Enough of what could’ve been you’re here because it is already stuck. In most cases the problem is that corrosion has built up on the linkage itself causing metal to lock up into one very solid piece. This may effect your low range/high range as well, but it doesn’t have to. Your low and high range function of the lever can work fine while the diff lock function remains stuck.

Instructions on how to test if your differential lock is engaging are at the bottom of the page.
If you don't like reading instructions there are photo links at the bottom of this page.
Fixing the stuck differential lock:
Brute Force non-technical methods.

1. The first thing you can try, assuming you haven’t already tried this, is standing outside the passenger side door and lean firmly back and forth on the lever. Depending on how strong you are if the lever shows no signs of movement after several tries you might want to consider stopping as you may snap the lever. Grabbing as low down on the lever as you can will help prevent this from happening.
2. You may also want to try unscrewing the boot over your transfer case lever. Just grab it and give it a turn and it will unscrew. Now you have the bare lever exposed. Take a piece of cloth or rag, your least favorite spanner, crowbar, hunk of metal, etc. and a decent sized hammer. Place the cloth around the base of the lever as far down as you can go. Then put your metal bar of choice on the cloth and give a few solid blows with the hammer onto the end of your bar. Be careful not to scratch your dash, center console, or break your passenger side door window with errant hammer swings. Depending on the corrosion on your linkage this may break things free enough to have step 1, above, work for you. If neither of these brute force techniques work and don’t be surprised if they don’t, you need to get a little more serious.

Method more likely to be approved by Land Rover Repair shops:

Give yourself some time to do this. If you are the type that wants to get it done in one haul give your self the whole day just in case you run into trouble. You might find better results doing this over two days though, which is fine because it doesn’t effect the drivability of the Disco. Make sure you check out the links to the photos at the bottom of this page too.
1. First thing to do at this point is crawl underneath the Disco on the passenger’s side with a flash light. Look up right behind the catalytic converter and you will see the transfer case that houses the diff lock. The long bar that comes down is the linkage that moves to engage the lock. When you pull the handle inside the car towards the driver’s side, to engage the diff lock, this bar pivots on the bolt in its middle and pushes the bottom out towards the passenger side. At the bottom of the bar you will find a C shaped link that goes from the bar to another link on the top of the transfer case. Taking a screw driver, chisel, or equivalent, and push this linkage up and off to disconnect the linkage in the vehicle from the transfer case. There will be two metal lock washers that are holding this on from below make sure you grab them. Also take note of which end of the C link you pulled out goes on which side, it only works one way as the ends are different length.
2. Now a 13mm socket to the top of the transfer case and with a small amount of force and only a little turn you should be able to engage and disengage the diff lock. You can have someone sitting inside with car in the on position to see if the diff lock light on the dash turns on and off as you move the socket. You may want to test the diff lock at this point to make sure it is working. See "Testing Your Diff Lock" at the bottom of this section. The lever inside the car should still be frozen solid. This is a good thing, you have now just determined that your transfer case is fine and it is only the linkage that is bad. This is the point in which you also have just saved yourself money as some dealers would have told you that you needed a whole new transfer box, even though that wasn’t the problem, and charged you a somewhat intriguing fee for their services.
3. At this point you can try taking a crowbar and wedging it up between the transmission and the bar that comes down and using leverage try and push or pull the bar towards the passenger side of the car, try this with a friend pulling on the lever. If this doesn’t seem like it is working stop, because you will bend that linkage bar. If you happen to own a can of “panther piss” or other noxious, Styrofoam melting, unsticker/lubricant in a can, spray some up on to the very top of the linkage, try to aim right where the metal rod goes into the silver box. If you do this, unless your can of weasel whiz has a good jet spray, grab one of those red WD40 straws and plug it into the nozzle to help keep your spray direct so you don’t accidentally melt wiring insulation. Also wear goggles so you don’t accidentally melt your glasses or your eyes.

4. Now that you have probably gotten dirty, go inside and wash up. The next step is removing the center console from your Disco. While you are doing this your nut and bolt looser you sprayed below should be doing some work for you. Here is how to take out the console. Take out the two bolts at the front of your diff lock lever underneath the boot. Then take out the two bolts inside your center console storage bin. Pull out the lighter part of your cigarette lighter, the housing can stay. Remove the plastic trim around the transmission selector by squeezing the sides in and pulling the back up and off. Then use a screw driver to push the front part forward and up. It sits in two plastic nubs that stick out and will break if you aren’t too careful. Throw your gear selector into neutral. At the front of the gear selector take a screw driver and while pulling the console backward pry the plastic past of the console, this is under the wood, up and over the ridge of the gear lever housing. Now you can move the wood trim piece around. Flip it up and around until the back with all the connectors comes up. Then disconnect the seat heaters, windows, etc. You might want to write down where they go, but trial and error when putting them back together is pretty easy too. Now you need to disconnect the emergency brake by pushing the spring clip off and removing the pin. Sure its easy to take off, just wait until you have to put that back on. You can now put the emergency brake lever straight up and down and move it easier. If you have power seats reach in and push the power seat buttons out so you can remove the connections. Reach under the front right side of the console and pull the connections for the cigarette lighter, there are two. You now should be able, with the help of mild profanity, to slide the entire console up and backwards over the transmission gear selector and the emergency brake.

5. Pull away the foam insulation and you should see the rubber gaiter sealing up the top of your lever mechanism. You now have options. You can cut along the very edge of the gaiter very carefully on the passenger’s side enough so you can pull it back over the lever and work. Or if you don’t want to cut the gaiter you can drill out the rivets that hold it in place. The choice is yours. If you drill out the rivets make sure you have some rivets to tighten things back up later. If you decide to cut the gaiter invest in some good glue and / or some silicone sealer. If you plan on doing water crossings or a lot of off roading you should drill the rivets to do the job right to make sure nothing gets past the seal. If you are in a hurry to fix the diff lock, cut the gaiter to get at it for a quick fix, but then drill out the rivets and install a new gaiter, about $15, sometime down the road. If you don't do a lot of off roading or dusty driving cutting the gaiter gives no drawbacks as long as you seal it up very carefully.

6. Now that you can see everything easily, you can try an assortment of degreasers and rust removers on the right side of the linkage box. It is also fairly easy at this point to unbolt the whole thing and take it out for a rebuild, but you probably don’t need to do that. Instead disconnect the bar that goes done to the box. There is a snap ring and pin on the top. The middle pin you can leave in or, if you have bent the bar or it is getting in your way you can pull the snap ring on it and pull the pin. You probably will have better luck doing this from below. Be advised the middle pin also has two white plastic bore reducers that will fall out when you remove the pin.

7. With the horizontal bar end exposed now hook an adjustable wrench or other leverage generating tool on the end of the bar and start working it forward and backwards. You may hear nasty sounds of rubbing corroded metal as you do this. You can have a friend work the lever left to right as you are rotating the pin. An occasional splash of corrosion remover and patience should eventually work that bar loose. You may want to soak the bar with corrosion remover and let it sit for a while and then hit again and let it sit some more. Just keep repeating this process and keep working the bar back and forth and it will eventually free up and your problem is solved. The lever should move very easily. If it moves some, but is stiff don’t seal things up until it really moves easily.
8. After you get the lever moving put the linkage back together again and connect it to your transfer case. Check to make sure the diff lock engages and then disengages. If you have bent the bar the light on the dashboard may not turn off even with the lever in the disengaged position. Take it apart and hammer the bar flat to fix this problem.

9. In putting everything back together, you may want to add some more grease into the inside of the box as long as you have it off. Make sure you use grease that won’t get stiff in the cold or break down in the heat. If you chose to cut the gaiter apply silicone on the black plastic along the edge of the hole then put the gaiter on top and then seal the top with more silicone to provide an air tight seal. Before you put the center console back together check the two bulbs that sit under the middle of the transmission gear selector and the bulb for the cigarette lighter. Chances are if you were beating the hell out of things earlier you quite possible burned out the filaments on all these bulbs. It is a lot easier to replace them now than put everything back together and then find out they are all out. Putting the emergency cable back in place can be a real pain too. Use a small pair of vice grips to pull the cable as far out as possible and then wedge it in place so you can let go of the vice grips and the cable will stay fully extended, leaving you free to move the lever and the pin.
10. Go get the Disco muddy.

Testing your differential lock to see if it is engaging and disengaging.
If you aren't sure if your diff lock is engaging or not, here is a quick way to test it. First the indicator light on the dash is not 100% accurate in determining if the diff lock is on. A bent linkage can make the light stay on or stay off regardless of what the diff is actually doing. Second driving on the highway with the diff lock engaged will cause odd handling, especially around corners, chirping of the tires, and ultimately destroy your transfer case or shatter your drive shafts. So it is important to know if your transfer case lever is properly engaging and disengaging the diff lock.
Start by attempting to engage the diff lock with the lever. Then jack up one front wheel, just one though. Throw the truck in neutral with something blocking the rear wheel so it doesn't roll off the jack. Try and spin the wheel that is up in the air. It should not spin if the diff lock is engaged.
Have someone sit in the Disco and move the lever while you try and spin the tire.
If the wheel spins when the diff lock is disengaged and doesn't spin when it is engaged then the diff lock works. Test it both ways. You may want to try this with the back too, but if one works the other should.
If you understand how the diff lock works you can see how this tests it. With one wheel on the ground the only way a free will can spin is if the lock is not engaged since on a Disco the lock is basically hooking the axles together for lack of a description, making all four wheels spin at the same speed.