Do You Need a Scan Tool for Subaru Brakes? DIY Guide & Tool Alternatives

Changing your brake pads is a routine maintenance task for any car owner, and Subaru vehicles are no exception. However, when it comes to Subaru brakes, particularly models equipped with an Electronic Parking Brake (EPB), a common question arises: Do you need a Scan Tool For Subaru Brakes? This guide will explore whether a scan tool is necessary for a Subaru brake job, especially when dealing with rear brakes and the EPB system, and present a DIY approach that might save you a trip to the dealership.

Understanding Subaru Brakes and the EPB System

Subaru vehicles are known for their reliability and advanced features, and many newer models incorporate an Electronic Parking Brake. Unlike traditional cable-operated parking brakes, EPB systems use electronic motors to engage and disengage the rear brakes. This system offers convenience and integrates with other vehicle safety features.

When you perform a rear brake job on a vehicle with EPB, the system needs to be put into “maintenance mode” to retract the electronic parking brake mechanism. This retraction is crucial to create space for new brake pads and to properly reset the system. Traditionally, accessing this maintenance mode has been thought to require a diagnostic scan tool.

Do You Really Need a Scan Tool for Subaru Brakes?

While a scan tool is often recommended and undoubtedly simplifies the process by electronically retracting the EPB, it’s not always an absolute necessity for a DIY brake job on Subaru vehicles. As demonstrated by experienced DIYers, it’s possible to perform a rear brake pad replacement on many Subaru models with EPB without using a scan tool. The key is utilizing a piston tool designed for retracting brake pistons, particularly those found in EPB systems.

This method involves manually winding back the brake piston, effectively backing off the EPB mechanism internally. This approach bypasses the need for electronic retraction via a scan tool, making brake maintenance accessible to home mechanics and saving on potential dealership costs.

Step-by-Step Guide to Subaru Rear Brake Job Without a Scan Tool

This guide outlines the process for replacing rear brake pads on a Subaru with EPB without using a scan tool. Disclaimer: Brake work is critical for safety. If you are not comfortable performing this task, please consult a professional mechanic.

1. Preparation and Safety First:

   • Ensure the vehicle is parked on a level surface, securely chocked, and the front wheels are blocked.
   • Gather all necessary tools and parts (new brake pads, piston tool, wrenches, Allen keys, brake cleaner, etc.).
   • Wear appropriate safety gear, including gloves and eye protection.

2. Accessing the Rear Brakes:

   • Loosen the lug nuts on the wheel you are working on.
   • Safely lift the vehicle using a jack and secure it with jack stands.
   • Remove the wheel.

3. Dealing with the EPB Wire:

   • Locate the EPB electrical wire connected to the caliper.
   • Carefully detach the wire from its securing clip behind the rotor shield to provide slack for caliper movement. Do not unplug the wire from the EPB motor.

4. Removing the Caliper and Old Pads:

   • Detach the retaining spring (pad clip) from the caliper. Exercise caution as it can have stored energy.
   • Remove the caliper guide pin caps.
   • Using a 7mm Allen key (size may vary), remove the caliper guide pins.
   • Rotate the caliper body away from the rotor. You can use an S-hook to hang the caliper from the strut spring, ensuring it’s supported and doesn’t strain the brake line.
   • Remove the old brake pads.

5. Retracting the EPB Piston:

   • Important: Open the brake fluid reservoir cap before compressing the piston. Place a clean rag over the opening to prevent spills and contamination. Monitor fluid level during piston retraction to avoid overflow.
   • Use a RH (right-hand threaded) piston tool. For Subaru rear brakes, you will typically rotate both driver and passenger side pistons clockwise to retract them.
   • Engage the piston tool and begin to spin the piston clockwise. You’ll notice the EPB mechanism retracting.
   • Periodically tighten the tool’s “jam nut” to apply inward pressure on the piston while spinning. Repeat this process until the piston is fully retracted, allowing enough space for the new, thicker brake pads.

6. Installing New Brake Pads and Reassembling:

   • Clean the caliper bracket and rotor area with brake cleaner.
   • Install the new brake pads in the caliper bracket.
   • Reinstall the caliper body over the new pads.
   • Grease the caliper guide pins with appropriate brake grease and reinstall them, torquing to the specified value (refer to your vehicle’s service manual for torque specifications, front and rear may differ).
   • Reattach the retaining spring.
   • Re-secure the EPB wire to its clip.
   • Repeat steps for the other rear wheel.
   • Reinstall the wheels and torque the lug nuts to the correct specification.
   • Close the brake fluid reservoir cap.

7. Post-Installation Procedure:

   • With the car off, slowly depress the brake pedal several times to allow the pads to contact the rotors.
   • Turn the car on and depress the brake pedal a few more times until you feel firm pressure.
   • Cycle the parking brake (engage and release) approximately 10 times with the door open so you can hear the EPB servo motors operating. This helps reset and adjust the EPB system.
   • Perform a bedding-in procedure for the new brake pads as recommended by the pad manufacturer. This usually involves a series of moderate to firm stops from medium speeds.

Essential Tools for Subaru Brake Job Without Scan Tool

To successfully perform a Subaru rear brake job without a scan tool, you will need:

• Piston Retraction Tool Kit: Crucial for retracting the EPB pistons. Ensure it includes right-hand threaded adapters.
• Allen Key Set: Typically a 7mm Allen key for rear caliper guide pins (confirm size for your model).
• Wrench Set: For lug nuts and potentially other bolts.
• Screwdriver Set: Flathead and Phillips head screwdrivers.
• Brake Pad Spreader (Optional but helpful): Can assist in compressing pistons initially if needed.
• Brake Cleaner: For cleaning components.
• Brake Grease: For lubricating guide pins and metal-to-metal contact points (excluding piston face).
• Jack and Jack Stands: For safely lifting and supporting the vehicle.
• Wheel Chocks: For safety.
• Gloves and Eye Protection: Personal safety gear.
• Torque Wrench: For accurate tightening of lug nuts and guide pins.

Important Considerations and Safety Tips

• Brake Fluid Level: Monitor the brake fluid reservoir level throughout the process. Bleeding brakes might be necessary if fluid is old or contaminated, but is not typically required for a pad replacement alone unless you have introduced air into the system.
• EPB Wire Handling: Be gentle when detaching and re-securing the EPB wire to avoid damage.
• Piston Rotation Direction: Always confirm the correct piston rotation direction (clockwise for most Subaru rears) to avoid damaging the EPB mechanism.
• Cleanliness: Keep all components clean during the process to prevent contamination and ensure proper brake function.
• Bedding In New Pads: Properly bedding in new brake pads is essential for optimal performance and longevity. Follow manufacturer recommendations.
• Double Check Everything: Before driving, thoroughly double-check all connections, bolts, and ensure the brake pedal feels firm.

Conclusion

While a scan tool offers a streamlined approach to Subaru brake jobs, particularly rear brakes with EPB, it is not strictly mandatory for DIYers. By using a piston retraction tool and carefully following the correct procedure, you can successfully replace your Subaru’s rear brake pads at home, saving money and gaining valuable experience. Remember to prioritize safety and consult a professional if you are unsure about any part of the process. This DIY method provides a practical alternative and empowers Subaru owners to handle their brake maintenance effectively.