We’ve covered all kinds of problems with the Ford F-150 before, but a more specific issue that some owners also run into involves the pickup truck’s 4WD (4-wheel drive) actuator.
The 4WD (or 4×4) actuator is an important component considering what the F-150 is built for, but unfortunately, it’s known to become faulty and cause several problems that you should be aware of.
In this guide, we’ll go over what these 4WD actuator problems are, their possible causes, and what you can do to resolve them. So be sure to stick around until the end!
What are the common problems of the Ford F-150 4×4’s actuator?
The Ford F-150’s 4×4 (4WD) actuator is known to have problems such as the 4WD system not engaging, the vehicle being stuck in 4WD mode, and a grinding noise developing at the front of the truck.
The Ford F-150’s 4×4 or 4WD actuator plays a crucial part in the engagement or activation of the truck’s 4-wheel drive mode, which enables all four wheels to be driven by the engine’s power.
However, once the 4×4 actuator malfunctions or stops working for any reason, the performance of the 4WD mode will be hampered and, in some instances, even completely fail to engage.
If you’ve already engaged 4WD mode as the actuator starts becoming problematic, you may even find yourself unable to disengage from it and revert back to the normal 2WD (4×2) mode.
Besides that, you may also hear some grinding noises coming from the front of the truck while you’re cornering or accelerating from a stop.
To get to the bottom of such issues, we need to look deeper into the nature of the problems and check different 4WD components to find the culprit.
4-Wheel Drive Doesn’t Engage
One of the most common problems brought about by either the 4WD actuator or other related components is the 4WD (4-Wheel Drive) mode not engaging or activating.
Despite turning the 4WD knob to either the “4A”, “4H”, or “4L” position, the 4WD system can still remain in the standard “2H” mode, which means that you’re stuck in 2-wheel drive mode.
Other F-150 4×4 owners have also observed that even if the 4WD light or icon is already displayed on the gauge, they still don’t feel any power delivered to the front wheels.
Furthermore, there are several symptoms that you should also look out for whenever the 4WD system suddenly doesn’t engage.
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Several different 4WD components, including the 4WD or 4×4 actuator, can be to blame for these symptoms whenever the 4WD system fails to engage.
Failed 4-Wheel Drive Actuator
The most likely culprit for the 4WD system not engaging on the Ford F-150 is the failure of the 4WD actuator itself, which is responsible for locking and unlocking the front wheel hubs to the axle shafts when selecting drive modes.
When 4WD mode is selected on the F-150, the actuator is supposed to connect the hubs to each of the axle shafts so that the front wheels are driven simultaneously with the rear wheels.
However, a failed or malfunctioning 4WD actuator will leave you either stuck in 2WD or 4WD mode depending on what setting you’ve already chosen before.
In newer models, the 4WD actuator is part of Ford’s IWE (Integrated Wheel End) system and is located in between the wheel hub and the outer cv joint of each axle.
On the other hand, older F-150 models from 1997 to 2004 have their 4WD actuators placed in front of the front differential and are covered by a heat shield.
As far as IWE actuators are concerned, they make use of a vacuum as a trigger to either engage or disengage the 4WD mode on the F-150.
Whenever 4WD mode is selected, the vacuum is taken away from the actuator by a solenoid inside the engine via some vacuum lines, which is the main triggering process that activates the actuator and engages 4WD mode.
This works the same way when you switch back to 2WD mode, except in reverse order. The vacuum enters and deactivates the actuator again via the solenoid, resulting in the 4WD mode being disengaged.
If you suspect that the actuator might have failed, then there are steps that you can take to check the condition of the component.
How to Test the Ford F-150 4WD Actuator:
Using a jack or lift, raise the front of the truck to better access the actuator within the IWE system.Disconnect the two vacuum lines from the 4WD actuator.Connect an external vacuum pump to the 4WD actuator.Using the pump, provide a vacuum to the actuator and release it afterward.Observe if the actuator’s teeth assembly moves outwards (engaged) and inwards (disengaged) when giving and releasing the vacuum, respectively.If the actuator moves as described in step #5, then it still works. But if it barely moves or doesn’t move at all, then it’s already faulty and needs replacing.
The cost of a replacement 4WD actuator for the Ford F-150 can start from as little as $30 to more than $100 depending on the exact model of your truck and the shop or brand that you buy the part from.
However, getting the job done at a local Ford dealer or any other reputable mechanic can add several hundred bucks more on top of the price of the parts.
Failed or Faulty Vacuum Solenoid
Aside from the 4WD actuator, there are several other components of the F-150’s 4WD or IWE system that can cause the 4WD mode to not engage, just like a failed or faulty vacuum solenoid.
As briefly mentioned in the last entry, the vacuum solenoid is located in the engine bay and is responsible for removing the vacuum from the actuator when engaging the 4WD mode and returning it when switching back to the 2WD mode.
More specifically, you can find the IWE system’s vacuum solenoid attached to the firewall that’s just behind the battery.
But just like the actuator, the solenoid can also potentially fail over time and will not be able to properly hold or release the vacuum throughout the truck’s IWE system.
One common reason why the vacuum solenoid fails is due to being exposed to moisture that builds up inside the engine bay. This is more so the case for older F-150 models that have no form of protective covering for their solenoids.
Fortunately, Ford actually includes a “rain cover” for newer replacement solenoids. So if your solenoid doesn’t come with one yet, we highly recommend getting one from your local dealer.
Testing if the vacuum solenoid still works will involve measuring the amount of vacuum pressure supplied to the vacuum lines as well as measuring the voltage of the solenoid itself.
There are vacuum lines both at the top and bottom of the solenoid, and you need to remove the ones at the top (next to the firewall) and plug in a vacuum gauge tester to them to measure the pressure while the engine is running.
These vacuum lines, when measured via their “check valves”, should register a minimum of 10 inches of vacuum on the gauge while in 2WD mode. The pressure should be held constant in 2WD and fall back to zero when engaging 4WD.
Furthermore, the vacuum solenoid should also have a minimum of 9 volts when measured with a voltage tester while 4WD is still disengaged, as recommended by the manufacturer.
By the time you turn the knob to select any of the 4WD settings, the solenoid should make a clicking sound and stop providing ground current to the voltage tester.
In addition, the voltage tester should also stop beeping when 4WD is engaged if you’re using something like a Power Probe tool.
Damaged or Torn Vacuum Lines/Hoses
The various vacuum lines or hoses in the Ford F-150’s IWE system make up a big chunk of it, which is why it’s also important to consider checking them out if you start to have problems engaging 4WD mode.
Such lines are crucial in maintaining the vacuum that flows between the solenoid and the actuator, so if a leak develops anywhere within the IWE system, you can bet that your ability to engage and disengage 4WD will also be affected.
The sample diagram below shows how the vacuum lines interconnect with the different parts of the IWE system to either supply or redirect the vacuum.
Any damage or tear to the vacuum lines will cause a loss in vacuum pressure, which may not be enough to keep the 4WD/IWE actuators from engaging or disengaging.
If a vacuum line leak makes the actuators engage 4WD while you’re driving, then this is one of the times you can experience the notorious “grinding” noise coming from the front of the vehicle.
Getting an entire vacuum line replacement kit will cost you about $75 to $100 on average, so it’s best to test the pressure of your vacuum lines first.
Luckily, you won’t be needing a vacuum gauge tester or a voltage tester this time. Though, you still need to remove the solenoid vacuum lines on the firewall like last time to do the test.
A black plastic housing holds the two vacuum lines on the solenoid together, but once you start the engine, only the line with the check valve should receive constant vacuum pressure.
The other vacuum line, otherwise, will only receive vacuum pressure once you switch from 2WD to 4WD mode. This will be the vacuum line that connects to the rest of the IWE system.
Simply connect the check valve line to the non-pressurized vacuum line so that you can check if the latter provides vacuum pressure up to the actuators.
The next step is to raise the front of the vehicle with a jack or lift. Observe if the front wheel hubs are still disengaged from the axles and can still freely spin on their own while the two vacuum lines are still connected.
If the situation above is what happens, then your vacuum lines are providing pressure to the actuators to keep 4WD disengaged and are still good to go.
However, if the axles also spin with the wheel hubs when you attempt to turn them, then there is a lack of pressure in the actuators due to a potential leaking vacuum line.
Faulty Transfer Case Shift Motor
Compared to the other 4WD/IWE components we’ve talked about, the Ford F-150’s transfer case shift motor is usually only diagnosed to be the culprit after you’ve already checked the actuator, solenoid, and vacuum lines.
This makes the transfer case shift motor quite a rare reason for the 4WD mode to not engage, though you’re more likely to have this issue if you have an F-150 model made before 2004.
Any F-150 models made before 2004 are more prone to have faulty or failed transfer case shift motors, which are responsible for making sure the appropriate drive mode is actually selected according to your input on the knob.
A faulty shift motor will not be able to select and engage the correct drive mode, leaving you stuck in whatever mode that you’re currently on.
Aside from their unlikelihood to go bad, transfer case shift motors are also quite expensive to replace at about $323 to $356 for parts and labor combined.
Vehicle Stuck in 4-Wheel Drive (4WD) Mode
If you’ve ever engaged the 4WD mode on your Ford F-150 but now can’t get out of it, then this is also a common problem brought about by the 4WD actuators not functioning properly.
Under normal circumstances, switching from 4WD back to normal 2WD mode should be a quick process.
But if you feel that the front wheels are still engaged after selecting 2WD (2H on the knob), then this means the actuators have failed to disengage them from the axles.
Alternatively, you may also refer to the procedure we’ve previously discussed in the “Failed 4-Wheel Drive Actuator” section on how to test the Ford F-150’s 4WD actuator (highlighted in blue).
If you’ve confirmed that the actuator is unresponsive to you giving and taking away its vacuum pressure, then the only option left is to replace it, which will cost between $30 and $100 in parts.
Grinding Noise from the Front of the Truck
Another common problem brought about by a failed 4WD or 4×4 actuator on the F-150 is a grinding noise that seems to come from the front of the vehicle.
When taking a closer look (or listening), the grinding noise actually comes from the front wheel hubs where the actuators are located.
The grinding noise usually occurs when you’re first accelerating from a stop or cornering. It also occurs more often when you’re in 2WD mode, which is when the actuators should be keeping the hubs unlocked.
The actuators are dependent on the truck’s IWE (Integral Wheel End) system to provide a vacuum to either engage or disengage them, so if they become faulty, they may only partly receive the required vacuum pressure.
This leads to the actuators being only partly disengaged (or engaged) from the hubs, which causes them to grind with each other and make that distinctive but annoying noise that owners have been reporting.
The demo video below provides a good example of what this issue can sound like while you’re driving in 2WD mode.
While both the actuators and the hubs can obviously get damaged due to the grinding, replacing them may only provide a temporary solution if there’s still an underlying issue with the other IWE system components.
This is why we also recommend checking your IWE system’s vacuum solenoid and vacuum lines for any signs of wear and tear, as they may be the ones to blame for the actuators failing in the first place.
How to Fix Ford F-150 4-Wheel Drive (4WD)
Fixing problems with the F-150’s 4WD should be started by first looking for damaged parts in the Integrated Wheel End (IWE) system.
IWE system components worth checking include the front actuators, front hubs, the vacuum solenoid, and vacuum lines. Replace any of these parts if found to be faulty.
4WD systems on 2005 and newer Ford F-150 models utilize the manufacturer’s own Integrated Wheel End (IWE) system, so any problems that concern the truck’s 4WD should be diagnosed and fixed according to the parts in said system.
The entire IWE system runs on vacuum pressure that is primarily supplied by the engine. This vacuum is also what engages and disengages the 4WD mode on the truck via the actuators.
Thus, if anything were to go wrong with the components of the IWE system, the normal flow of the vacuum will be affected and 4WD engagement will also become problematic.
While you’ll eventually end up replacing one IWE component or another, properly diagnosing a 4WD problem will still require you to test the performance of the components beforehand.
If you’ve already read our guide above on how to perform such tests but are not much of a DIY-er, then we always recommend leaving the job to a professional mechanic.
Frequently Asked Questions (FAQs)
