Why Are Your Brake Lights and Turn Signals Not Working?

Driving down the road and suddenly realize your brake lights or turn signals aren’t working properly? This common car problem can happen to anyone, but can be frustrating and dangerous if left unaddressed.

Functioning brake and turn signals are extremely important for safe driving. So when they stop working, it’s crucial to diagnose the issue and make repairs right away.

In this comprehensive guide, we’ll cover everything you need to know about malfunctioning brake and turn signal lights.

The Purpose of Brake and Turn Signal Lights

Before diving into why your car’s brake and signal lights may not be working, let’s review what these lights do:

Brake Lights

Brake lights are the red lights that illuminate at the rear of your vehicle when you press the brake pedal. They alert other drivers that you are slowing down or stopping.

Most cars have two brake lights, one on each side of the vehicle rear. Some larger vehicles like trucks may have three.

These lights are crucial for safety. They give a visual warning to other motorists, preventing rear-end collisions. Driving without properly functioning brake lights significantly increases your chances of an accident.

Turn Signals

Turn signals, also known as directional signals or blinkers, are flashing lights that indicate when you are turning or changing lanes. The blinking lights cue other drivers of your intended movements.

Turn signals have amber lenses in North America and red lenses in the rear for the rest of the world. Most cars have a turn signal on each side, front and back.

Properly using turn signals is vital for safe lane changes and turns. Like brake lights, they provide a valuable visual warning to prevent accidents.

Common Causes of Brake and Turn Signal Failure

Several issues can cause brake lights and turn signals to stop working properly. Let’s look at the most common culprits:

Burnt Out Bulb

The simplest and most common reason your brake or turn signals have gone dark is a burnt out light bulb. All incandescent bulbs eventually burn out over time.

On older vehicles, the brake lights and turn signals may use the same bulbs. So when one burns out, both brake and turn signal functions stop working on that side.

Fixing burnt out bulbs is an easy DIY fix. You just need to locate the bad bulb, remove it, and install a replacement. Auto parts stores have replacement bulbs for all makes and models.

Blown Fuse

The electrical circuits for the brake lights and turn signals are protected by fuses in your car’s fuse box.

If either system draws too much current, the fuse blows to protect the rest of the electrical system. Fuses stop working long before wires actually overheat or catch fire.

When a fuse blows, it cuts power to everything on that circuit – causing all lights it controls to go dark.

Testing and identifying blown fuses is straightforward. You can then replace blown fuses with new ones of the proper amperage. Your vehicle owner’s manual shows fuse box locations and identifies the proper fuse for each circuit.

Faulty Brake Light Switch

For your brake lights to operate, your car has a brake light switch that gets triggered when you press the brake pedal.

This switch activates the brake light circuit to illuminate the lights. If this switch fails, the brake lights won’t come on at all when braking.

The brake light switch is located near the brake pedal and wired into the pedal arm. Switch failure can happen due to physical damage, corrosion, or normal wear over time.

Replacing a faulty brake light switch will require locating the switch and disconnecting wiring before installing the new replacement switch.

Bad Turn Signal Flasher Relay

The blinking action of your turn signals is controlled by a flasher relay. This electrical component interrupts the signal power intermittently to create the flashing light.

When a flasher relay fails, it will cause abnormal blinking patterns or prevent the turn signals from flashing completely.

Diagnosing a bad turn signal relay is done by process of elimination. If bulbs and fuses check out, the flasher is likely faulty. These relays are easy to replace by swapping in a new functional unit.

Damaged Wiring

Damaged or deteriorated wiring in the brake light or turn signal circuits can cause operating problems.

Exposed wiring that short circuits against the vehicle chassis is a common cause of trouble. Other issues like chafed, cut, or pinched wires can interrupt power flow.

Diagnosing wiring issues takes more time but begins with visual inspection of all wiring and connectors. Checking wires for continuity can help isolate breaks. Wiring repairs involve splicing, soldering, or full replacement.

How to Diagnose Your Brake and Turn Signal Problems

Determining exactly why your brake lights and turn signals have stopped working properly is the key to making the right repairs. Here is a systematic approach you can use to diagnose the problem:

1. Check All Lights

The first step is cycling through all brake and turn signal lights while watching their operation.

Turn on the ignition so the lights are powered up. Press the brake pedal and verify both brake lights come on.

Activate each turn signal and check that the front and rear turn signal on that side flashes correctly. The other lights shouldn’t illuminate at all.

This test will identify which side and type of light has the issue. It will also reveal if you have total brake or turn signal circuit failure.

2. Inspect Bulbs

With the faulty light identified, inspect each of the bulbs and sockets involved.

Remove the bulb by turning or squeezing the socket to release it. Look for a darkened or broken filament on incandescent bulbs.

For LED lights, see if they are damaged or corroded. Also check that they are the right bulb type and properly installed.

If you find any bad bulbs, try replacing them with new ones to see if that solves the problem. Burned out bulbs are the most likely culprit, especially if more than one light is affected.

3. Check System Power Supply

The next step is verifying that the electrical system is delivering power to the lights involved.

Start by locating the fuse box and identifying the fuses that protect the brake light and turn signal circuits. Check if any of those fuses are blown. Replace any blown fuses.

If the fuses are good, use a multimeter to test voltage at the fuse box terminals while the lights are on. You should read approximately 12-14 volts.

No power at the fuse points to a short circuit or open somewhere in the supply wiring. Consult a qualified auto technician if complex electrical diagnosis is required.

4. Isolate the Problem Source

If the bulbs and fuses check out okay, isolate the source of the problem based on which function is affected:

  • Brake lights only – test the brake light switch
  • Turn signals only – test the turn signal flasher relay
  • Both brake and turn signal lights – test associated wiring harnesses and connectors

By methodically narrowing down the malfunctioning component, you can zero in on the repair needed to get your lights working again.

Making the Necessary Repairs

Once you’ve diagnosed why your brake or turn signal lights are malfunctioning, it’s time to make the repair.

Carefully follow all directions and safety procedures for the specific repair. Use replacement parts designed for your vehicle. Let’s look at how to fix the most common problems:

Burnt Out Bulb Replacement

Replacing burnt out bulbs is fast and easy in most vehicles:

  1. Disconnect the battery negative terminal to avoid sparks.
  2. Remove the bulb socket by turning it counterclockwise or squeezing a release tab.
  3. Extract the old bulb from the socket. Do not touch the new bulb with bare fingers.
  4. Insert the new bulb, aligning the bulb base correctly in the socket.
  5. Reinstall the socket into the light assembly and turn it clockwise to lock.
  6. Reconnect the battery after the repair is complete.

Be sure to only replace bulbs with the same type, wattage, and connector. Consult your owner’s manual if you have any uncertainties.

Fixing a Blown Fuse

Here is the basic process for replacing a blown fuse:

  1. Locate the fuse box and use the fuse diagram to find the fuse controlling the malfunctioning lights.
  2. Pull the fuse straight out from the fuse box using the provided fuse puller tool.
  3. Visually inspect if the thin metal strip inside the fuse is broken or melted.
  4. If blown, replace it with a new fuse of the exact same amperage rating. Never use a higher amp fuse.
  5. Push the new fuse into the empty slot until it clicks into place.
  6. Turn on the lights to confirm proper operation.

Replacing a Faulty Brake Light Switch

Follow these general steps to replace a malfunctioning brake light switch:

  1. Locate the switch near the brake pedal arm. Trace wires to identify switch terminals.
  2. Disconnect the switch wiring harness connector.
  3. Remove any retaining clips or fasteners to detach the switch from the pedal arm. Caution: Do not disturb pedal position.
  4. Install the new switch in the exact same position. Do not overtighten fasteners.
  5. Plug in the wiring connector to the switch. Ensure connection is fully locked.
  6. Test brake pedal operation before driving. Brake lights should now illuminate.

Fixing Electrical Wiring Issues

For damaged wiring causing problems, repair options include:

  • Splicing – Joining cut wires by stripping insulation, twisting together, soldering, and covering with electrical tape or heat shrink tubing.
  • Soldering – Heat fusing wires and applying solder to create solid electrical joints.
  • Replacing – Rerunning damaged sections of wiring with new automotive-grade wiring.
  • Weatherproofing – Using heat shrink connections or sealant tape to protect exposed wiring.
  • Routing – Repositioning wiring away from hot or moving components causing damage.

Electrical repairs require meticulous work for reliable connections. Consider hiring an experienced auto electrician for complex jobs.

Staying Safe While Lights Are Malfunctioning

Once you discover brake lights or turn signals not operating properly, your top priority should be safety until it can be fixed. Here are some precautions to take:

  • Avoid driving at night or in bad weather when lights are crucial.
  • Do not drive on highways or busy roads with higher speeds.
  • Tap brakes lightly to flash brake lights if driving without them.
  • Use hand signals if turn signals are not working properly.
  • Increase following distance to allow more reaction time for other drivers.
  • If you must drive, activate your emergency flashers to alert other cars.

You can also reduce your brake light usage by coasting to stops as often as possible. But the best choice is to call for a tow and refrain from driving until lights are repaired if feasible.

While broken lights are mostly considered “secondary” violations, you could still receive a moving traffic citation and points on your license in some areas. So make the fix quickly not just for safety, but to avoid tickets too.

Can Insurance Help With Repair Costs?

Since brake and turn signal repairs are not collision damage, auto insurance generally won’t directly reimburse the costs. Insurance is meant to cover accidents, not maintenance issues.

However, there are a couple ways your insurer could potentially assist:

  • If an electrical fault caused a fire, resulting wiring repairs may be covered under comprehensive claims.
  • Usage Based Insurance (UBI) programs may provide discounts or rewards you can use towards general vehicle repairs and maintenance.

For the most part though, you’ll need to pay brake light and turn signal repair bills yourself or file them under your vehicle warranty if still covered.

The Bottom Line

It can be unnerving when those vital red brake lights or blinking turn signals stop illuminating when they should. But in most cases, a few straightforward checks can uncover the cause, and a quick DIY fix will get them working properly again.

To recap, follow these steps if your brake lights or turn signals malfunction:

  • Inspect all lights to identify which one is affected.
  • Check bulbs, fuses, switches, relays, wiring based on symptoms.
  • Make necessary repairs like replacing bulbs, fuses, bad parts.
  • Take safety precautions driving with faulty lights.
  • Consider filing under warranty or insurance in certain cases.

Regularly monitoring all exterior lights will help you catch and correct problems promptly. Proper brake light and turn signal operation is a must for collision avoidance and avoiding tickets. So address any issues immediately to keep yourself and others safe on the roads!

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