John Deere tractors and mowers come equipped with a differential lock. This feature locks together both axles, ensuring the tires turn together in unison for enhanced traction when driving on slippery surfaces. However, it is not uncommon to experience problems with your JD diff lock over time.
But what are the common John Deere differential lock problems, you ask? Well, sometimes the diff lock may get stuck or not turn off. The diff lock pedal is also susceptible to breaking over time around the section where it joins to the shaft. In addition, the component may fail to engage or become stiff to operate.
So, how do you fix all these John Deere diffs lock problems? Check out our guide below to find out.
Problems With The John Deere Differential Lock Table
Below is a quick summary of the various problems of John Deere differential lock and their solutions.
| Problems | Solutions |
| Stuck Diff Lock | Depress the diff lock pedal entirely |
| Stomp on the brake | |
| Release any hydraulic pressure | |
| Adjust the diff lock | |
| Diff Lock Not Turning Off | Reconnect the diff lock pedal |
| Replace the solenoid | |
| Change the diff lock switch | |
| Diff Lock Pedal Breaking | Weld the diff lock pedal together |
| Replace the broken diff lock pedal | |
| Failure to Engage | Replace the bushing for the diff lock pedal and the entire pedal |
| Install new valve body and pins for the diff lock linkage | |
| Replace the blown-out fuses | |
| Replace the solenoid | |
| Stiff Operation | Remove any stuck objects from the diff lock linkage |
| Spray some lubricant on the linkage | |
| Spin only one of the rear tires slowly |
What Are the Different John Deere Differential Lock Problems
Let’s check out the typical problems with the John Deere differential locking system without further ado.
1. Stuck Differential Lock
One of the frequent problems with the John Deere differential lock is the component getting stuck or locked. When this occurs, the differential lock pedal will be halfway depressed and won’t release to its normal position.
Also, the rear tires may pull together at the same speed, including when making turns. Sometimes, the diff lock may refuse to budge downward, not even an inch. This problem affects all John Deere tractor models, mainly the JD X748 and JD 6610.
By the way, this problem may occur if the differential lock is out of adjustment or due to too much hydraulic pressure. Sometimes, the stuck diff lock may be due to a binding diff lock linkage rod.
Solution
Apart from some adjustments, there are no replacements here to do. You can solve this problem by following the steps below:
- Step 1: Drive your tractor or mower straight slowly and depress the diff lock pedal entirely. Then, hold and count to 10 before releasing the pedal while still driving.
- Step 2: Stomp on the brake sharply with a quick release.
- Step 3: Let the tractor sit with the engine off for a while to relieve any hydraulic pressure.
- Step 4: Check if the linkage between the diff lock and brake pedal is binding. If binding, apply some lubricant.
- Step 5: Adjust the diff lock if it is out of adjustment.
Tip: Jacking up the rear tires off the ground may help release the tension on the diff lock and get it unstuck.
2. Diff Lock Won’t Turn Off
With the John Deere 6610, the differential lock may refuse to disengage. In this case, you will find that all the wheels will spin simultaneously, regardless of traction. As such, the tractor may not get enough torque to move forward and may quickly get stuck.
Apart from the diff lock being disconnected, another cause of this problem is a faulty differential lock switch.
Solution:
You will need to perform a few replacements here. That said, the following are steps on how to solve this issue with your JD diff lock:
- Step 1: Connect the differential lock pedal if it has been disconnected.
- Step 2: Check if the solenoid for the diff lock is powered to release the diff lock and replace it.
- Step 3: Inspect the differential lock switch and replace it if damaged.
Tip: To determine if the diff solenoid is working, run new wires from the solenoid to the switch and to the power source.
3. Differential Lock Pedal Breaking
Over time, some of the differential lock components usually start to wear. The diff lock pedal is one of these components. Due to wear and tear, the diff lock pedal may break on the part where it goes on the shaft.
This may happen when you budge the pedal to get it unstuck. Typically, you may encounter this problem with the John Deere 2630 models.
Solution:
To fix this issue, you should follow the steps below:
- Step 1: Weld the diff lock pedal back together.
- Step 2: Replace the broken differential lock pedal.
Tip: After installing a new diff lock pedal, replace the freeze plug to keep dirt and water out of the transmission.
4. Failure to Engage
The diff lock may fail to engage with the 2011 John Deere 872GP and 1982 Deere 4840 models. Sometimes, the problem may occur suddenly without any prior sign. Other times, the lights may illuminate the dashboard to warn you.
One of the causes of the diff lock failing to engage is a worn-out bushing for the pedal. It could also occur due to broken pins for the linkage, a frozen valve body, lousy ground for the solenoid, or a blown fuse.
Solution:
To solve this problem, here are different solutions you should try out:
- Replace the bushing for the diff lock pedal and the entire pedal
- Change the pins for the diff lock linkage and the valve body
- Check if the solenoid has good ground and replace it
- Replace any blown-out fuses
Tip: Always maintain optimal hydraulic oil levels in your John Deere. This is because the diff lock is hydraulically operated.
5. Stiff to Operate
The differential lock of the John Deere tractor may become stiff, making it hard to operate. So, while the diff lock will engage, it may budge downward slower. Sometimes, it may move but not go down to the floor completely.
Generally, this problem may occur if you stay too long without using your tractor or the diff lock feature. Lack of proper lubrication or something lodged in the linkage may also stiffen the diff lock.
Solution:
There are just a few repairs for this problem. You can follow the steps below to solve this problem:
- Step 1: Inspect the diff lock linkage for any lodged objects and remove them.
- Step 2: Apply lubricant on the diff lock linkage.
- Step 3: Move one of the rear tires slowly and try engaging the differential lock to get the diff lock linkage working.
Tip: Never engage the diff lock while spinning one tire rapidly and the others moving. This may damage the diff lock spider gears.
Final Words
Like other tractor brands and models, the John Deere differential lock is prone to several issues. For example, the component tends to get stuck due to a binding linkage or too much hydraulic pressure. Besides that, the diff lock may fail to turn off, engage or become stiff to operate.
Now, while there are many causes of these John Deere differential lock problems, there are also solutions. However, it is recommended that you seek the help of a qualified mechanic to fix these problems. This is if you don’t have the necessary expertise and tools.
