Brake and Battery Light On: Possible Reasons and Solutions

Brake lights are part of the many warning lights on the vehicles’ dashboard that notifies drivers of developing problems. The battery light, on the other hand, indicates an issue with the battery. Sometimes, two unrelated lights can illuminate simultaneously on the vehicle’s dashboard, creating confusion.

So, why are the brake and battery lights on? Some of the reasons these two warning lights are on include electrical connection issues, like a short circuit or a loose connection, brake system issues, and low brake fluid. Battery charging issues, like due to a faulty alternator or voltage regulator, are also possible causes.

The article discusses various reasons why these two lights come on simultaneously and their solutions. Keep reading.

Brake Light and Battery Light on Causes and Solutions Overview

The following table provides an overview of the causes and solutions why the brake and battery light comes on.

Causes		Solutions
Battery and Battery Charging issue	Faulty alternator Malfunctioning voltage regulator Corroded battery terminals	Replace alternator Replace burnt resistors Clean the terminals
Electrical Connection Problems	Loose or damaged wiring Loose ground wires Short Circuit	Replace damaged plugs and wires Clean and reattach loose ground wires Replace frayed wires
Issues with the Brake System	Low brake fluid Faulty Brake Switch Brake pad wear	Top up brake fluid Replace brake switch Replace brake pads

Below is a detailed discussion of the issues;

1. Battery and Battery Charging Problems

The two warning lights can come on together due to battery-related problems. Battery issues affect the vehicle’s electrical system, which can cause issues with the braking system, triggering the light. This scenario is more common where a vehicle is equipped with an electric braking system.

Car Battery and Battery Charging Problems

Some of the battery charging problems behind the two warning lights include;

A) Faulty Alternator

The alternator charges the vehicle’s battery when the engine runs and provides other components with power. The alternator gets damaged due to corrosion, short, loose wiring, or a bad battery. When the alternator is damaged, it doesn’t give the battery and various car components power.

The solution to a bad alternator is to replace it. Usually, repairs related to a vehicle’s electrical system should be handled by a professional. However, if you have a basic understanding of the vehicle repairs, you can change it by following the steps below;

Step 1. Disconnect the vehicle’s battery
Step 2. Locate the alternator. Refer to your user manual if you can’t locate it
Step 3. Remove bolts and the serpentine belt

Step 4. Remove the old alternator
Step 5. Install the new one

B) Malfunctioning Voltage Regulator

The voltage regulator manages the amount of power from the alternator, preventing overload to the car’s components. Overheated electrical components and damaged ground wires are some of the reasons behind a malfunctioning voltage regulator.

Some of the solutions to a malfunctioning voltage regulator include;

Ensure all connections towards and from the voltage regulator are well secured.
Replace burnt resistors and capacitors. The steps include;

Step 1. Turn off the engine and locate the burnt resistors and capacitors, they’re usually on the circuit board.
Step 2. Disconnect the wiring to the resistor or capacitors and in some cars use the disordering tool.
Step 3. Clean the board and solder the new parts back on.

Step 4. Test to see if the lights are off.

Ensure the power to the voltage regulator is within the required range.
Ensure the voltage regulator can disperse heat ideally to avoid overheating.

C) Corroded Battery terminals

Corroded battery terminals interfere with the current flow to and from the battery. The battery corrodes due to exposure to humidity, especially during warm seasons. Corrosion means the battery doesn’t charge enough and produces low power when needed.

The solution to corroded battery terminals is to clean them. Follow the steps below;

Step 1. Disconnect the battery cables

Step 2. Apply cleaner or a baking soda and water solution
Step 3. Use a brush to scrub the terminals
Step 4. Connect the batteries back on

Step 5. Test the vehicle

Read: 4runner Brake Light Not Working [ 5 Common Problems And Solutions]

2. Electrical Connection Problems

Various electrical connection problems affect the effectiveness of battery charging and braking systems and interfere with their operations. These issues can cause the brake and battery light to come on.

A) Loose or damaged wiring

Loose or damaged wiring in various parts of the car’s electrical system, like the alternator, battery, and brake system, can trigger the lights. The wiring can become frayed or damaged with time as the vehicle ages.

The solutions to the loose wiring causing the brake and battery light to come on include;

Check for frayed or damaged wiring to these electrical systems and fix them. Frayed wires can be fixed using electrical tape or heat-shrinking tubing.
Replace the more damaged wires with new ones.

Ensure the connection points are properly secured.
Replace broken plugs. The steps include:

Step 1. Turn off the vehicle and set it to park brake

Step 2. Identify the faulty wiring plugs
Step 3. Disconnect the plug
Step 4. Add new plugs and reconnect the wiring

Step 5. Check whether the warning lights go off

B) Damaged or Loose ground wires

The ground wires complete the circuit in a car’s electric system, allowing them to work seamlessly. As the vehicle ages, the ground wires can become loose or damaged, interfering with electricity flow and triggering various warning lights, including the brake and battery lights.

The following are some solutions to damaged or loose ground wires causing the two warning lights to illuminate.

Check the ground wire connection from the battery to the chassis and ensure it connects on a clean surface. Use a cleanser or scrub the surface with sandpaper to remove rust on the connections.
Tighten the ground connection points to ensure they are tight.
Check for damaged ground wires and replace them.

C) Short Circuit

A short circuit happens when the electrical current gets on a line. It’s not supposed to be in a system. The short happens in the car’s electrical system from various parts, including connectors and wiring harnesses.

The short causes damage to wires and blows fuses, triggering various warning lights, including these two. The solutions to this problem include;

Check and fix any loose harnesses in the electrical system.

Repair damaged wiring and avoid further damage through a short circuit.
Replace the faulty connectors. The steps include;

Step 1. Disconnect the battery.

Step 2. Identify the faulty connector to the brake light and disconnect it.
Step 3. Follow the steps in the user manual for specific steps for preparing and installing the new connectors. They vary with vehicle models.
Step 4. Reconnect the battery.

Step 5. Check if the lights go off.

Insulate damaged or frayed wiring. The steps include;

Step 1. Disconnect the car battery.

Step 2. Access the frayed wiring.
Step 3. Use an electric tape to insulate the wiring.
Step 4. Confirm whether the short is gone and the two warning lights go off.

3. Issues With the Brake System

As mentioned earlier, issues with the braking system can cause the two warning lights to illuminate. The brake light comes on to notify the driver of a problem with the braking system. The battery light can come on as a secondary light.

These issues include;

A) Low Brake Fluid

Low brake fluid usually causes the brake light to come on, followed by a battery light as a secondary warning light. Brake fluid gets low due to a leak in the system and damaged brake pads.

The solutions include

Check for leaks in the system and provide a fix.
Top up the brake fluid to ideal levels. Usually, this is between the min and max lines.

B) Faulty Brake Switches

The brake switch activates when the driver depresses the brake pedal. With time, the brake switches malfunction and get stuck in a closed position, triggering the brake light. In this case, the battery, which powers the brake switches, can come on to indicate an electric system problem.

Read: Brake Light Won’t Turn On: What to Look for First?

The solutions for malfunctioning brake switches include;

Locate the brake switch and test it through a sensor to tell if it is still functional or needs replacement. Usually, it’s near the brake pedals

Replace the brake switch if necessary. Below are the steps to follow for replacement;

Step 1. Disconnect the vehicle’s battery
Step 2. Locate the brake switch, usually near the brake pedals

Step 3. Unscrew or unclip the brake switch. Disconnect the wiring too.
Step 4. Screw or clip back the brake switch and reconnect the wiring.

C) Brake pad wear

The brake pad wear sensor monitors the level of wear on the brake pads. When the pads are worn to a certain level, it sends signals to the system, activating the brake light on the dash.

If the sensor malfunctions, the battery light can also activate to signify an issue with the vehicle’s electrical system. The solutions include;

Confirm brake pad wear
If the pads are worn out, replace them and the light should turn off.

Follow the following steps;

Step 1. Lift the vehicle on the wheel with worn brake pads
Step 2. Remove the wheel

Step 3. Remove the brake calipers
Step 4. Remove the worn brake pads
Step 5. Install replacement brake pads

Step 6. Reinstall the calipers
Step 7. Breed the brakes

If the brake pads are not worn out, the sensor is faulty. Replace the brake pad wear sensor in the following simple steps;

Step 1. Locate the brake pad sensor usually on brake pads or calipers
Step 2. Lift the vehicle and remove the wheel
Step 3. Remove the calipers to access the brake pads and the sensor

Step 4. Remove the faulty sensor then replace it with a new one.
Step 5. Reinstall the calipers and then the wheel.
Step 6. Check if the light goes off

Having both the brake and battery light illuminate on your dashboard can be perplexing and concerning. While you’re navigating this issue, it might be beneficial to understand other unusual brake light behaviors in vehicles. For example, there’s the unexpected situation where the brake light activates during acceleration. Additionally, another baffling scenario some drivers have encountered is when the brake fluid light remains on even though the fluid level is full. These articles can offer insights into the intricacies of brake system indications, helping you address potential concerns more effectively.