So you had some 4WD fun and now ready to hit the road back but you can’t get your 4WD to disengage 4WD. This is not a pleasant situation and there are a few fundamental things you need to consider before taking action. The solution will differ drastically depending on if you have a traditional 4WD system or a more modern electronic variant.
If your 4WD is stuck in 4H and you drive a non-permanent 4WD then you need to do the following:
- Stop immediately and assess for any obvious signs of damage
- Do not attempt to force the gear stick or transmission lever out of 4H while stationary
- If possible, park with 2 wheels on one side onto a slippery surface (grass/snow/mud/sand)
- Drive forward about 2 car lengths and reverse 2 car lengths a few times
- While doing so, try disengaging the 4WD shift lever
If your vehicle is stuck in 4WD then you probably have some drive-train build-up happening. In a case like this you want to try to loosen the tension as best as possible without causing serious damage to your transmission or transfer case.
With the advancement of technology in 4WD systems, each 4WD might have a different cause for getting jammed in 4WD mode. Depending on which vehicle you drive, the problem might even be electronic. Let’s now look at a few scenarios which best suites your 4WD type.
What happens when your truck is stuck in 4 wheel drive?
Permanent 4 wheel drive means the vehicle cannot be removed or taken out of 4×4 (4H)mode at all. This means the vehicle is always in 4WD mode and very similar to an AWD vehicle. There is no risk of operating and driving it on ANY particular surface in this mode. Traditional Permanent 4WD trucks makes use of a drive-train component (viscous coupling) that allows the drive-shafts to operate independently while turning without causing any drive-line wind-up.
NB: if your 4WD has the ability to lock its centre differential, always ensure that it is disengaged or unlocked before you venture back on to the tarmac or any hi-traction surface.
Part-time 4 wheel drive or 4×4 means the vehicle can be operated in 2-wheel drive mode as well as 4WD mode and this is up to the drivers discretion. These modes can be selected with a short gear stick in the older 4×4’s or the more modern Utes and trucks make use of an electronic 4×4 turn dial option.
Most vehicles with part-time 4WD modes have a low range transfer case making it very capable off-road, much more so than AWD vehicles. A part-time 4WD vehicles are propelled by the rear wheels in 2H mode, usually on the tarmac and other high traction surfaces. This allows the vehicle to deliver decent fuel economy on-road while having the ability to offer excellent off-road capabilities in 4H and 4Lo when needed.
Let’s look at a few common causes of 4WD systems getting jammed.
Most 4WD trucks have an actuator that is a major component of your 4WD system. The actuator is designed to automatically lock the wheel hubs when selecting 4H. When you engage your 4WD, the transfer case engages the front drive shaft to send torque to the front axle.
The Actuator allows you to engage or disengage 4WD on your vehicle without the hassle of exiting the vehicle to manually engage the front hubs. Those days are gone!
If you drive a truck similar to the Ford F150, you can test if the actuator is meshing and engaging by removing both lines and with the front still raised, the front CV shafts should be engaged and should be rotating as well.
When there is a vacuum in the lines the hubs will disengage and the truck will be in 2WD. Once the vacuum pressure is activated the 4WD will be engaged when the hub and actuator spline are engaged.
Faulty Transfer case
As you might have gathered by now, there are many reasons why your 4WD fails to disengage 4H. It could be any of the following:
- bent or broken gear link
- low transfer case oil
- bad actuator
- drivetrain binding etc.
The transfer case gears could also be damaged thus resulting in your 4WD being jammed in 4H. This of course is the worst case scenario and requires the transfer case to be removed and stripped by a professional to assess the damage.
Damaged or loose gear Linkages
The factory linkages on certain older model Jeep Wranglers have been known to working themselves loose or breaking completely. The TJ Wranglers 4WD operating ranges are selected with a floor-mounted shift lever. The shift lever is connected to the transfer case range lever by an adjustable linkage rod.
The short low-range gear selector requires a nice firm yank to get it into and out of 4H properly. The newer, more modern Wranglers makes use of a dial function that operates an electric motor to engage 4WD.
If the linkage has just worked itself loose, and this can be caused by old-age or regularly traveling on corrugated roads. It’s a relatively simple procedure to adjust the linkage and all you’ll need to do is, adjust the set screw, and you’ll be good to go. No special tools or expertise is required. If this happens often or reoccurs soon, you might want to consider upgrading the factory linkages to a cable shift option instead.
Low Transfer case oil
You need to also make sure the transfer case fluid is topped up. When draining the TC, check for any metal filings. This will indicate excessive heat build-up caused by high levels of friction.
If the lubrication levels are low, the friction will increase causing major wear on gearing components. This will also result in the transfer case not engaging and disengaging properly when you are driving and attempting to switch to 4WD mode or switch back to 2H mode before driving on a high traction surface.
If you have forgotten to remove your 4WD from 4H before heading back onto the Bitumen/Asphalt you will definitely experience transmission wind-up. One way to determine that you have transmission windup is if your vehicle is stuck/jammed in gear. You can yank and hang on the gear lever, releasing that gear by hand will be virtually impossible. This is due to the massive forces built up inside the gearbox jamming up the transmission components.
The easiest way to fix bind-up is by pulling over to the side of the road with two wheels firmly on the bitumen/asphalt and the other 2 wheels on a slippery surface like grass, mud, or sand. This allows the wheels to all rotate at slightly different speeds which can slowly release the wind-up in the transmission. Get your vehicle to a qualified drivetrain specialist as soon as possible for a full inspection.
The other option is to reverse in the same direction you were driving. So if you were driving forward in a left direction, reverse in a left direction in an attempt to allow the wind-up in the transmission to undo itself gradually. Make sure you do this in a safe environment void of any oncoming traffic or pedestrians.
The solenoid calculates the difference in pressure of your vacuum pipes, which allows it to engage and disengage 4WD mode. If you experience the 4WD symbol flashing on the dash without you attempting to engage 4H then you need the check your solenoid. When this happens there is often grinding noises coming from your drivetrain as your 4WD systems tries to engage while you are driving.
Is it bad to leave your truck in 4WD?
If you’re reading this, you most likely drive a 4WD and have concerns about the potential damage you could be causing by leaving your truck in 4 Wheel Drive, perhaps parked in 4H overnight, or driving in 4H for extended periods at a time. It is important to be aware of the potential damage you could cause if you do not operate your vehicle within the operating specification as set out by the manufacturer in the owner’s manual. Yeah right! nobody reads that thing…
With that being said, unintentional misuse or abuse could cause extensive and expensive damage to your 4WD.
So in order to get the correct answer for your vehicle application, we need to understand one important fact and that is, there are essentially two types of 4×4’s.
A full-time 4WD which is essentially a permanent 4 wheel drive
A part-time 4 wheel drive. Non-permanent 4×4
So what is the difference and how does it affect the operation of the vehicle?
Unless traction is bad, It is not advised to drive in 4WD mode for extended periods of time with a non-permanent 4×4 as this will result in “axle binding”, also known as ”drive-line binding” or “drive-line wind up”. Extended driving in 4-Hi, with a part-time 4WD truck, on a high traction surface like pavement, will result in drive-train components like u-joints, axle, transfer gears, bearings, and drive-shafts getting damaged and eventually failing.
The article below will discuss the risks of operating your 4WD in a specific setting or 4WD modes for extended periods.