Subaru Rear Wheels Not Spinning: Causes & Fixes

by Alex Braham 48 views

Hey guys! Ever been in that frustrating situation where you hit the gas in your Subaru, and the front wheels eagerly take off, but the back ones? They're just chilling, not contributing a thing. It's a classic sign that something's up with your Subaru rear wheels not spinning. This article is your go-to guide to understanding why this might be happening and, more importantly, what you can do about it. We'll dive into the common culprits, from simple fixes to potentially more complex issues, so you can get your Subaru back on the road and enjoying its legendary all-wheel-drive (AWD) capabilities (if equipped!). Let's get started!

Understanding the Basics: How Subaru AWD Works

Before we jump into troubleshooting, let's quickly recap how Subaru's AWD system usually functions. Most Subaru models utilize a system that, under normal driving conditions, sends power primarily to the front wheels. When the system detects a loss of traction (like on a slippery surface), it intelligently distributes power to the rear wheels to help maintain control and stability. This is what sets Subaru apart, offering enhanced grip and performance, especially in challenging weather. Several components work together to make this magic happen, including the center differential, viscous coupling (in some models), and various sensors that monitor wheel speed, throttle position, and steering angle. Understanding this basic principle is crucial for pinpointing the issue when your Subaru rear wheels aren't spinning. If only the front wheels spin, then the problem is isolated to the power transfer to the rear, not the engine itself. Understanding how your specific Subaru model's AWD system functions will help you in your diagnosis. Now, let's explore some of the common reasons why your rear wheels might not be spinning.

Common Causes of Subaru Rear Wheel Spin Issues

Alright, let's get down to the nitty-gritty. When your Subaru rear wheels are not spinning, several components could be the source of the problem. Here’s a breakdown of the most common causes, ranging from simple to more complex fixes.

1. Blown Fuse

This is usually the first and easiest thing to check. In many Subarus, the AWD system has a dedicated fuse. If this fuse blows, it can disable the rear wheel drive. Locate your fuse box (usually under the hood or inside the cabin) and consult your owner's manual to identify the fuse related to the AWD or rear wheel drive system. Inspect the fuse for any breaks in the filament. If the fuse is blown, replace it with a fuse of the same amperage rating. This is the simplest fix, and in some cases, it's all that's needed to restore the function of your rear wheels.

2. Defective Wheel Speed Sensor

Each wheel has a speed sensor that monitors its rotation. The AWD system relies on these sensors to determine when to send power to the rear wheels. If one of these sensors fails, it might send incorrect information to the system, preventing it from engaging the rear wheels. You might get a warning light on your dashboard, like the ABS light or the traction control light. Diagnosing a faulty wheel speed sensor often requires a scan tool to read the error codes. Replacing the sensor can sometimes be a straightforward fix. Be sure to purchase the correct sensor for your specific Subaru model. The location of the wheel speed sensors varies depending on the vehicle. You'll likely find them near the wheels, attached to the hub or knuckle.

3. Faulty Center Differential or Viscous Coupling

This is where things get a bit more complex. The center differential is responsible for distributing power between the front and rear axles. In some Subaru models, a viscous coupling (VC) helps in this power transfer. If the center differential or VC fails, it can prevent power from reaching the rear wheels. Symptoms can include the car feeling sluggish or the front wheels spinning while the rear ones remain stationary. Diagnosing a center differential or VC issue often requires a mechanic, as it may involve disassembling and inspecting these components. Replacement can be costly, so it's essential to have a qualified technician diagnose the problem accurately.

4. Transmission Problems

In some cases, the issue might stem from problems within the transmission itself. Issues like a malfunctioning valve body or internal mechanical failures can prevent power from being delivered to the rear wheels. This can be difficult to diagnose without a mechanic. A transmission repair can be expensive, and it is usually best left to a professional.

5. Damaged Driveshaft or Axle

If the driveshaft, which connects the transmission to the rear differential, is damaged or broken, the rear wheels won't receive any power. Similarly, a damaged axle can also prevent the wheels from spinning. Check for any visible signs of damage, such as dents, cracks, or leaks. A damaged driveshaft or axle will usually require professional repair or replacement. In some cases, you may notice unusual noises coming from the rear of the car.

6. Transfer Case Issues (For Models with a Transfer Case)

Some Subaru models, particularly those with more rugged off-road capabilities, use a transfer case. The transfer case is responsible for sending power to both the front and rear axles. If the transfer case fails, your rear wheels might not spin. The transfer case is similar to the center differential, and its repair will require a mechanic.

Troubleshooting Steps: How to Diagnose the Issue

Okay, so you're staring at your Subaru, frustrated by those uncooperative rear wheels. Don’t panic! Here's a systematic approach to help you diagnose the issue. Let's get to it!

1. Visual Inspection

Start with a visual inspection. Check the following:

  • Tires: Ensure your tires are in good condition and properly inflated. Uneven tire wear can sometimes affect AWD performance.
  • Driveshaft: Look for any signs of damage or leaks on the driveshaft. Make sure the driveshaft is properly connected to the transmission and rear differential.
  • Axles: Inspect the axles for any signs of damage or grease leaks from the CV joints.
  • Under the Car: Look for any obvious signs of damage, such as broken or hanging components.

2. Check Fuses

Locate your fuse box and consult your owner's manual to identify the fuse related to the AWD system. Remove the fuse and inspect it for a broken filament. If it's blown, replace it with a fuse of the same amperage.

3. Scan for Diagnostic Trouble Codes (DTCs)

If you have a scan tool, connect it to your Subaru's OBD-II port (usually located under the dashboard). This will allow you to read any diagnostic trouble codes stored in the system. These codes can provide valuable clues about the problem. Even if you don't have a scan tool, you can often take your car to an auto parts store, and they may be able to read the codes for free.

4. Test Drive (Carefully)

Find a safe area, such as an empty parking lot, and try accelerating. Pay attention to whether the rear wheels are engaging. If you have any doubt, do not try this on a public road. If you have a friend available, have them watch your rear wheels as you accelerate. Note any unusual noises or sensations. Be cautious and prioritize safety during this test.

5. Consult a Professional

If you've tried these steps and are still unsure of the problem, or if the issue seems complex, it's best to consult a qualified mechanic. They have the tools and expertise to diagnose and repair the issue accurately. They can also use specialized equipment like a lift, which can make inspecting components much easier.

DIY vs. Professional Repair: When to Seek Help

So, when should you roll up your sleeves and get your hands dirty, and when should you seek professional help? The answer depends on your comfort level with car repair, your access to tools, and the complexity of the problem.

DIY Repair Options

  • Fuse Replacement: Replacing a blown fuse is a straightforward task that most people can handle. It requires no special tools and is an easy first step.
  • Wheel Speed Sensor Replacement: Replacing a wheel speed sensor can be a DIY project if you have some mechanical experience. However, it requires some basic tools and the ability to follow instructions.

When to Call a Mechanic

  • Center Differential/Viscous Coupling Issues: Diagnosing and repairing these components requires specialized tools and expertise. It's best left to a professional.
  • Transmission Problems: Transmission repairs are complex and usually require a mechanic.
  • Driveshaft/Axle Damage: While you might be able to visually inspect these components, repairing them can be tricky and may require special tools.
  • Uncertainty: If you're unsure of the problem or uncomfortable working on your car, it's always best to seek professional help. A mechanic can diagnose the issue accurately and make the necessary repairs.

Preventative Measures to Keep Your Subaru Spinning

Alright, you've got your Subaru rear wheels spinning again. Awesome! But how do you prevent this from happening in the future? Here are some preventative measures to keep your Subaru's AWD system running smoothly.

Regular Maintenance

  • Fluid Changes: Regularly change the fluids in your transmission and differentials according to the manufacturer's recommendations. This helps to keep the components lubricated and functioning correctly.
  • Inspect Components: During routine maintenance, have your mechanic inspect the driveshaft, axles, and other AWD components for any signs of damage or wear.
  • Tire Maintenance: Regularly check your tire pressure and ensure that your tires are in good condition. Uneven tire wear can put extra stress on the AWD system.

Proper Driving Habits

  • Avoid Aggressive Driving: Avoid excessive acceleration and hard cornering, as these can put extra stress on the AWD system. Although Subaru's are known for their performance, use them responsibly!
  • Be Mindful of Slippery Conditions: In snowy or icy conditions, drive carefully and avoid sudden starts and stops. Gradual acceleration and deceleration will help prevent wheel spin and reduce stress on the AWD system.

Following Subaru's Recommendations

  • Use the Recommended Fluids: Always use the fluids recommended by Subaru for your specific model. Using the wrong fluids can damage the AWD system.
  • Follow the Maintenance Schedule: Adhere to the maintenance schedule outlined in your owner's manual. This will help to catch any potential problems early on.

By following these tips, you can help to ensure that your Subaru's AWD system remains reliable for years to come. Remember, regular maintenance and proper driving habits are key to keeping your rear wheels spinning and enjoying the legendary performance of your Subaru.

Conclusion: Keeping Your Subaru on the Move

So there you have it, guys! We've covered the common reasons why your Subaru rear wheels might not be spinning, how to troubleshoot the issue, and what you can do to fix it. From a simple fuse replacement to more complex repairs, understanding the potential causes is the first step toward getting your Subaru back on the road. Remember to always prioritize safety, and don't hesitate to seek professional help if you're unsure about any repairs. Keeping your Subaru's AWD system in good working order ensures that you can enjoy its excellent handling and performance, no matter the weather. Keep your Subaru maintained and enjoy the ride!