All Brake Lights Not Working 2017 Toyota 86: Diagnosis & Fixes

Experiencing a complete failure of your brake lights on a 2017 Toyota 86 can be alarming and significantly compromise your safety on the road. When you press the brake pedal and none of the rear lights illuminate, it's a critical issue that requires immediate attention. This isn't just about avoiding a ticket; it's about preventing rear-end collisions, as other drivers rely on your brake lights to anticipate your actions. A non-functional brake light system renders your vehicle unsafe to operate, making prompt diagnosis and repair paramount. This comprehensive guide will walk you through the common reasons why all brake lights might fail on your 2017 Toyota 86 and provide a step-by-step approach to diagnose and fix the problem, ensuring you can get back on the road safely.

What drivers notice on this 2017 Toyota 86

The most obvious and concerning symptom is the complete absence of illumination from any of the brake lights when the brake pedal is depressed. This includes both the left and right tail lights (when functioning as brake lights) and the center high mount stop lamp (CHMSL). Drivers typically discover this problem when a passenger or another motorist informs them, or during a routine vehicle check before driving. The car itself might not display any warning lights directly related to the brake lights, making external observation crucial. This lack of a dashboard indicator can sometimes lead to drivers operating their vehicle unknowingly without functional brake lights, highlighting the importance of regular visual checks.

At a glance: difficulty, repair cost, and diagnostic workflow

• Difficulty Rating: 6/10 — Moderate
• Common Symptoms: No illumination from any rear brake lights: This is the defining symptom, affecting the left, right, and center brake li; Cruise control malfunction: On many vehicles, including the Toyota 86, the brake light switch also signals the cruise co; ABS or Traction Control warning lights: While less common for a simple brake light failure, a short or fault within the ; Shift Interlock Issues: In automatic transmission models, a faulty brake light switch can sometimes prevent the shifter
• Estimated Repair Cost: $150–$1,100 (parts + typical shop labor)
• OEM Tooling Required: Standard OBD-II scanner and hand tools

Diagnostic workflow:

1. Confirm the symptom on your vehicle.
2. Scan for stored or pending codes with an OBD-II tool.
3. Inspect the most common causes in this guide (visual checks first).
4. Run verification tests before replacing parts.
5. Repair, clear codes, and verify on a test drive.

Symptoms and warning signs

When all brake lights are not working on your 2017 Toyota 86, the primary symptom is unmistakable, but other related issues might also surface:

• No illumination from any rear brake lights: This is the defining symptom, affecting the left, right, and center brake lights simultaneously. This indicates a fault upstream in the circuit, affecting all lights rather than individual bulbs.
• Cruise control malfunction: On many vehicles, including the Toyota 86, the brake light switch also signals the cruise control system to disengage. If the switch is faulty or the circuit has an issue, your cruise control might not activate at all, or it might disengage unexpectedly, or even fail to disengage when the brake pedal is pressed (a dangerous scenario).
• ABS or Traction Control warning lights: While less common for a simple brake light failure, a short or fault within the brake light circuit could, in rare cases, trigger related system warnings if shared components, sensors, or grounds are affected. A faulty brake light switch can sometimes be interpreted by the vehicle's computer as a brake system anomaly.
• Shift Interlock Issues: In automatic transmission models, a faulty brake light switch can sometimes prevent the shifter from moving out of 'Park' because the car doesn't register that the brake pedal has been pressed.

How to verify and confirm the issue

Confirming that all brake lights are indeed out on your 2017 Toyota 86 is straightforward but requires a second person or a reflective surface:

1. Visual Confirmation: Have a friend or family member stand behind your vehicle while you press the brake pedal. Verify that neither the left, right, nor the center high mount stop lamp illuminates. If you're alone, back up to a garage door or reflective window and observe the lights in your rearview mirror.
2. Check the Fuse Box: Locate the fuse box, typically under the hood (main fuse box) or in the driver's footwell (interior fuse box). Consult your owner's manual for the exact location and diagram. Identify the fuse labeled "STOP" or "BRAKE" (or similar). A blown fuse is often the simplest explanation for a complete brake light failure. Visually inspect the fuse for a broken wire or use a fuse tester. Always replace a blown fuse with one of the exact same amperage rating.
3. Brake Pedal Switch Check: Manually verify the brake light switch operation. With the ignition on (engine off), press the brake pedal. Listen for a faint click near the pedal, which indicates the switch is activating. You can also try to manually push the plunger on the switch to see if the lights briefly illuminate (this might require disconnecting it first, which leads into more detailed diagnosis).
4. Scan Tool Use (Limited but Potentially Helpful): While there isn't typically an OBD-II code specifically for "all brake lights not working," a scan tool can be useful for checking related systems. For instance, if your cruise control is also malfunctioning, a scan tool might reveal codes related to the brake pedal position sensor or switch, which is often integrated with the brake light switch. This can indirectly confirm an issue with the brake light switch circuit. Remember, this is not an OBD code article, but a scan tool can offer diagnostic clues for related systems. For a comprehensive list of diagnostic procedures, you can refer to our All repair guides.
5. Check for Technical Service Bulletins (TSBs): Sometimes, manufacturers issue TSBs for known issues that affect certain models or years. While less common for a simple brake light failure, it's worth checking if Toyota has released any TSBs related to the 2017 Toyota 86's brake light system or associated components. These can offer specific diagnostic steps or repair procedures from the manufacturer.

Common causes for all brake lights not working

When all brake lights fail simultaneously, it usually points to a single point of failure affecting the entire circuit, rather than individual bulbs. Here are the most common culprits:

• Blown STOP Fuse: This is the most frequent cause. The STOP fuse protects the brake light circuit. An electrical short somewhere in the system or an overload can cause it to blow, cutting power to all brake lights.
• Faulty Brake Light Switch: Located near the brake pedal, this switch completes the circuit when the pedal is pressed, sending power to the brake lights. If the switch fails internally (e.g., contacts wear out or get stuck), it won't send the signal, and the lights won't activate.
• Wiring Issues:
  • Corrosion: Over time, wiring harnesses can suffer from corrosion, especially in areas exposed to moisture, leading to poor connections or open circuits.
  • Damaged Wires: Physical damage, chafing, or rodent damage to the main wire supplying power to the brake lights can interrupt the circuit.
  • Loose Connections: A loose connector at the fuse box, brake light switch, or a main harness junction can prevent power flow.
• Grounding Issues: While less common for all lights to fail due to a single ground point (as brake lights often share grounds with other tail light functions), a compromised main ground for the entire rear lighting assembly or the brake light switch circuit could cause a complete failure.
• Faulty Body Control Module (BCM) or Relay: In modern vehicles, the BCM often controls various electrical functions, including lighting. If the BCM or a dedicated brake light relay (if present) malfunctions, it could prevent the brake lights from working. This is a less common but more complex issue.

Related guides on this vehicle

• 2019 Toyota Tacoma Brake Pedal Feels Low: Diagnosis & Fixes
• Gas Nozzle Keeps Clicking Off 2017 Toyota 86: Vent System Fixes
• Car Won't Start, No Click, No Crank 2017 Toyota Rav4 Diagnosis

Step-by-step diagnosis

Before starting any diagnostic work, always ensure your vehicle is safely parked on a level surface with the parking brake engaged and the engine off. Consider disconnecting the negative battery terminal if working with electrical components to prevent accidental shorts.

1. Check the STOP Fuse:

   • Locate the fuse box (refer to your owner's manual).
   • Identify the fuse labeled "STOP" or "BRAKE."
   • Using a fuse puller, remove the fuse and visually inspect it. A good fuse will have an unbroken wire inside; a blown fuse will have a visibly broken wire or darkened glass/plastic.
   • Use a multimeter to test for continuity across the fuse terminals if visual inspection is inconclusive.
   • If blown, replace with a new fuse of the exact same amperage. If it blows again immediately, there's a short circuit that needs to be located.

2. Inspect and Test the Brake Light Switch:

   • Locate the brake light switch mounted near the top of the brake pedal arm. It typically has a plunger that is depressed when the pedal is released and extends when the pedal is pressed.
   • Visual Inspection: Check for any loose wiring or physical damage to the switch.
   • Manual Test: With the ignition on (engine off), carefully remove the electrical connector from the switch. Using a jumper wire, momentarily connect the two power terminals on the vehicle's harness side (consult a wiring diagram if unsure which terminals are power). If the brake lights illuminate, the switch is faulty.
   • Multimeter Test: With the switch disconnected, use a multimeter to check for continuity across the switch terminals. The switch should show continuity (closed circuit) when the plunger is extended (pedal pressed) and no continuity (open circuit) when the plunger is depressed (pedal released). If it doesn't behave this way, replace the switch.

3. Check for Power at the Brake Light Switch:

   • With the ignition on, use a multimeter to check for 12V power at the input side of the brake light switch connector (the vehicle's wiring harness, not the switch itself).
   • If there's no power, trace the wire back towards the fuse box to identify where the circuit is interrupted. This could indicate a wiring break or an issue further upstream.

4. Check for Power at the Brake Light Sockets:

   • If the fuse and switch appear to be functioning correctly, the next step is to check for power at the actual brake light bulb sockets.
   • Remove a brake light bulb assembly.
   • With the brake pedal pressed (have a helper), use a multimeter to check for 12V at the positive terminal of the bulb socket.
   • If there's power, but the lights aren't working, confirm the bulbs themselves are not faulty (though unlikely all would fail simultaneously). Also check the ground connection at the socket.
   • If there's no power, the issue lies in the wiring between the brake light switch and the rear lights, or a faulty relay/BCM.

5. Inspect Wiring and Ground Connections:

   • Visually inspect the entire wiring harness leading from the front of the vehicle to the rear lights. Look for any signs of chafing, cuts, corrosion, or loose connectors. Pay close attention to areas where the harness passes through body panels or near exhaust components.
   • Verify the ground connections for the rear lights. A poor ground can prevent lights from illuminating even with power present. These are typically bolted to the vehicle chassis. Ensure they are clean and tight.

Repair solutions

Once you've identified the root cause, implementing the repair is usually straightforward:

• Replace Blown Fuse: If the fuse was the culprit, simply replace it with a new one of the correct amperage. If it blows again, a short circuit must be found and repaired before replacing the fuse again.
• Replace Brake Light Switch: If the switch tested faulty, purchase an OEM or high-quality aftermarket replacement specifically for your 2017 Toyota 86. Installation usually involves disconnecting the electrical connector, unthreading or unclipsing the old switch, and installing the new one. Ensure proper adjustment if required.
• Repair Wiring: For damaged or corroded wiring, the best solution is to splice in a new section of wire using appropriate connectors (crimp or solder) and heat shrink tubing for protection. Ensure all connections are secure and weatherproof. Loose connectors should be cleaned and resecured.
• Address Grounding Issues: Clean any corroded ground points with a wire brush and ensure they are tightly re-fastened to a clean, bare metal surface on the chassis.
• Professional Assistance: If after these steps you are unable to pinpoint the issue, or if it points to a more complex problem like a faulty BCM or internal short, it's best to consult a qualified automotive technician. They have specialized diagnostic tools and expertise to handle intricate electrical problems. You can also explore more specific vehicle information by browsing our vehicles database.

Prevention and maintenance

Regular checks and preventative maintenance can help avoid future brake light failures and ensure your safety:

• Routine Visual Checks: Make it a habit to check your brake lights regularly, perhaps once a week or before long trips. A quick check against a reflective surface or with a helper takes seconds.
• Inspect Wiring During Service: When performing other maintenance, take a moment to visually inspect visible wiring harnesses for any signs of wear, damage, or corrosion.
• Address Issues Promptly: Don't ignore intermittent brake light issues or related symptoms like cruise control problems. Addressing small issues early can prevent larger failures.
• Proper Fuse Replacement: Always use fuses of the correct amperage. Using an incorrect fuse can lead to more severe electrical damage or fire hazards.
• Professional Inspections: Include a check of your vehicle's lighting system as part of your regular scheduled maintenance with a trusted mechanic.

Frequently Asked Questions (FAQ)

Can a bad brake light switch cause other electrical problems?

Yes, a faulty brake light switch can cause several related issues beyond just the brake lights not working. It can affect your cruise control system (preventing activation or disengagement), cause automatic transmission shift interlock problems (preventing shifting out of Park), and in some rare cases, trigger related warning lights if the vehicle's computer detects an anomaly in the brake system's input from the switch.

Is it safe to drive my 2017 Toyota 86 if all brake lights are not working?

No, it is absolutely not safe or legal to drive your 2017 Toyota 86 if all brake lights are not working. Brake lights are a critical safety feature that warns drivers behind you when you are slowing down or stopping. Driving without them significantly increases your risk of a rear-end collision, especially at night or in heavy traffic. You should address the issue immediately before driving the vehicle.

How much does it cost to fix brake lights on a 2017 Toyota 86?

The cost to fix brake lights on a 2017 Toyota 86 can vary significantly depending on the cause. A blown fuse might cost only a few dollars for the fuse itself. A faulty brake light switch typically ranges from $20 to $100 for the part, plus an hour or two of labor (approximately $50-$200) if done by a mechanic. More complex issues like wiring harness repair or a faulty Body Control Module could range from several hundred to over a thousand dollars, depending on the extent of the damage and labor rates. Always get a diagnostic estimate from a reputable shop.

Disclaimer

This article is intended for informational purposes only and is not a substitute for professional advice from a qualified technician. Automotive repairs can be complex and dangerous. Always consult with a certified mechanic or follow your vehicle's service manual for specific procedures and safety precautions. ClearTheCode is not responsible for any damage or injury resulting from the application of this information.

Related pages

• All repair guides
• Browse vehicles

Explore related guides on ClearTheCode

• Browse OBD-II codes
• All repair guides