Why Wont My 4 Wheel Drive Engage?

My four wheel drive is not working, what should I do? Why wont my 4 wheel drive engage? Worry not, we heard your anguished cries and are here to help you solve this problem!

Out of the heavy-duty solid trucks available on the roads, the four-wheel drive (4WD) is probably everyone’s top pick. But even these monsters of the road can sometimes suffer problems. Whether it is a big issue or just a little one, you need to know the root causes behind this problem. 

One common complaint that we hear from 4WD users is that the four-wheel-drive doesn’t engage. The lights will blink on the dashboard, but the rider is not able to make it function. 

But don’t worry, we are here, and we will talk about how you can troubleshoot this problem in case your 4WD is failing to engage. So, read on and find out everything regarding this topic. 

Why Wont My 4 Wheel Drive Engage

What Is An Actuator?

An actuator of a 4WD locks all the differentials, thus engaging the 4WD when the driver puts on the switch from inside the cabin. The axle actuator usually contains all the gears and the shift fork that helps in the locking process once the driver gives the signal. 

After the engagement, all four wheels will function as a single unit, and the most significant advantage is that the off-road traction will improve a lot. 

In earlier times, vacuum hoses were used by 4WD makers to make everything work together by using pressurized air. The pressurized air automatically works with the transfer case and activates gears to lock the differential. However, nowadays, most 4WD actuators use electronic solenoids to do the same job. 

So, whenever the driver puts on the switch to activate the differential locker, a process is triggered, making all the drive shafts function as a single unit, as mentioned earlier. The process occurs automatically in most of the 4WDs. 

As an owner of a 4WD, you need to inspect all the components inside the actuator, such as the locking collar, shift lock, and most importantly, gears, from time to time to assess their condition. They need to be lubricated from time to time. If you don’t take care of them, moisture can get in, which can damage the whole system and cause the 4WD lock to not engage. 

You might like toread: Why Is My 4 Wheel Drive Light Flashing: 7 Reasons

Blinking of Light in 4WD

Frequently engaging your 4WD system means ensuring everything is still functioning, so you’ll want to keep an eye out for the flashing red 4×4 light on your dash. 

Most mechanics will advise you to do this exercise as often as possible to keep all the components inside the transfer case lubricated and keep the actuators engaged. 

Even though each vehicle may have a different type of 4WD system, the owner’s manual always emphasizes reactivating the system regularly. 

A technical problem caused the 4WD system to turn off properly, which is evident by the flashing dash light. Any of the following could also cause it:

  • Several causes of defective 4WD systems include corroded wires or dials
  • Faulty transfer cases or actuators
  • Poor lubrication and leaks in the vacuum hoses (older, traditional 4WD systems).
  • Faults in the solenoid. 

By utilizing a few essential tools, a quick troubleshooting exercise can easily identify or narrow down the cause of the problem.

Why Wont My 4 Wheel Drive Engage

Problems in Fluid Levels

It is essential to ensure differential and transfer case oils are always topped up if you live in a cold climate. These fluids help in cooling and lubricating the gears. 

Good synthetic oil can prevent your differential from freezing up in sub-zero temperatures. Like any other oil, these oils also break down over time, and this contamination process is accelerated if the differential has been in contact with water. 

You should warm up your vehicle before engaging any 4WD system during extremely cold weather. If you frequently drive off-road or tow a boat, caravan, or off-road trailer, the differential fluid will break down more rapidly. 

There are three main reasons why differential oil breaks down faster: 

  • You often drive on rough and wet tracks 
  • You drive in deep snow, thick sand, or buggy mud quite a bit and put a great deal of strain on the drivetrain. 
  • You launch a boat regularly, and the axle might be partially underwater. 

You might like to read: 4 Wheel Drive Jerks When Turning – What to Do?

Disruption in Electrical Connections

If a wire corrosion occurs, it will result in voltage and current flow degradation, which may cause dips and irregularities within the signal transferred through the wire that a detector may interpret as a fault. 

This is often the case with any switch wires or electrical coil connections. The 4WD mechanism won’t operate correctly, causing the dashboard light to flash. 

This is more likely to happen if you frequently drive cross-country wherever the tracks are wet and muddy or if you cross rivers or drive typically in snow.

Do not use piercing probes in your 4×4

Never test the cable with a piercing probe when checking electrical wires on a 4×4 or another vehicle. After you drill tiny holes in cable insulation, it permits wetness to penetrate quickly, increasing the chance of cable corrosion. 

Ensure all couplings are clean and there is no moisture

Once coupling your 4WD, ensure that all electrical connections are correctly clean and sprayed with a decent quality silicone polymer electrical spray to stop moisture buildup. 

On 4×4 vehicles, most electrical connections are well insulated. However, there’s invariably a risk of wire corrosion. This may affect the practicality of your 4WD system if left unbridled and might bring you down after you least expect it.

With newer 4WDs, everything is electronically controlled, and every system is answerable for an important task, unlike differential switches and actuators. Your 4×4 has many electrical connections that send completely different signals from sensors. 

Why Wont My 4 Wheel Drive Engage

A Faulty Switch

When you have a faulty switch, you may need to press the button many times before the 4×4 dashboard lightweight stops flashing. The drawback is that after the 4H is activated, the four-wheel-drive system can not be disengaged easily. 

The switch being faulty will cause all kinds of weird problems with the system. If you believe the switch is faulty, take the 4WD to a knowledgeable lineman to check and examine if the switch has to be replaced. 

If you wish to take the DIY approach, take away the four-wheel-drive switch from the dashboard and check for any irregularities or flaws. This may affect the working of your 4WD system if left unchecked and may bring your vehicle down once you least expect it. 

This could be a tiny drawback, and it’s usually best to begin troubleshooting inspections from the smallest, most cost-effective item first to the most expensive item later.

You might like to read: What Does 4 Wheel Lock Mean?

Frequently Asked Questions

#1. How do I get my 4-wheel drive to engage?

To engage the four-wheel drive, you need to keep the speed between 7 to 30 miles per hour, and then you need to pull the lever from 2H to 4H. 

#2. How do you diagnose a 4WD problem?

Ans. There are several indications from which you can diagnose a problem in 4WD. They are:

  • Reduced traction when driving on snow or mud. 
  • Rattling noise while engaging 4WD. 
  • Wearing out of the front tire and several others.

#3. How do you reset the four-wheel drive?

At the bottom of the fuse box, you need to pull the five amp TCCM thread bridge, and after that, you need to be patient. After half an hour, just by replacing the fuse, you will be able to reset the four-wheel drive. 

Why Wont My 4 Wheel Drive Engage

A Few Final Words

Engaging the 4WD system in your car is good because though it may not prevent the packing up of the components, this helps you to know whether there is a problem in the system or not. 

As mentioned in this article, the best way to protect your 4WD is to lubricate it. You should also check the electrical cables regularly as the problem might be. 

So, if you begin troubleshooting the problem, then start inspecting the smaller parts of the system like the lubrication level, switches, and wires, and then if you don’t find anything there, move to the electronic components. If you cannot solve the problem on your own, take it to a professional car mechanic. 

Thank you for reading, we hope this has helped solve your problem. If you have further questions, feel free to drop us a word in the comments and we will get back to you soon.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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