How this system works:
During the day time, or when the headlights are off, rear lights only illuminate to indicate when a driver is braking. At night, or when the headlights are turned on, the rear lights illuminate constantly to let other drivers know where you are, and illuminate brighter when braking. Your rear lights are controlled through the same switch that controls the headlights. Power is channeled through a relay to the rear lights, illuminating them when the switch is engaged. A brake light switch, which is typically connected to the brake pedal, illuminates the brighter brake lights when the brake pedal is pressed.
Common reasons for this to happen:
- Blown Fuse: As a first resort, a mechanic should expect the corresponding fuse for your rear lights. When a fuse blows, it prevents the circuit from completing, in this case preventing the rear lights from illuminating. Sometimes when a taillight lens cracks or breaks, it can allow moisture to enter the lens and cause a short circuit, blowing the fuse.
- Burned Out Bulbs: In the case where only one of your rear lights appears to be out, the cause is most likely a burned out bulb. When the filament breaks inside a bulb, it cannot illuminate the gas inside the bulb. A burned out bulb will not affect the circuit of the entire rear light system, and the other rear light should continue to function normally.
- Bad relay: A relay transfers power from the battery to the lights themselves, but when a relay fails, the connection is unable to be completed. A relay may also fail because it is not grounded properly. A wire that is not grounded properly is unable to protect the circuit and provide an outlet for excess charge that build up. A vehicle with a bad relay or bad ground may not be able to successfully power your rear lights.
- Bad Brake Light Switch: If the rear lights illuminate normally but do not become brighter when braking, the brake light switch may not be functioning properly. The brake light switch circuit is completed when the brake pedal is pushed, but if the switch has been pushed out of place or is not connecting properly, the brake pedal may not be able to complete the circuit, meaning that the lights will not illuminate.
What to expect:
A top-rated mobile mechanic will come to your home or office to determine why your tail lights have failed. The mechanic will then provide a detailed inspection report outlining the nature of the failure and the cost of any repairs that need to be made
How it’s done:
When checking electric components on your vehicle, especially, fuses and relays, the mechanic will bring a multimeter which will help him or her diagnose what specific component has failed. The mechanic will begin by examining the back of the car for any superficial damage like broken tail light covers, and loose, or frayed wiring. If there is no superficial damage, the mechanic will then begin to examine the different components along the electrical circuit.
The mechanic will begin inspecting the various electrical components of the vehicle by looking at the fuses. If he or she suspects a blown fuse, they will remove the corresponding fuse for the tail lights to see if it is blown. If so, the mechanic will then replace it with a fuse appropriately rated for the amperage.
If only one of the tail lights appears to be out, the mechanic should check to see if the unlit bulb is burned out. Over time, bulbs will eventually fail and need to be replaced. The mechanic will check the filament in the unlit bulb to see if it is broken. If so, he or she will replace the bad bulb with a new one.
If the bulbs and fuses appear to be working properly, the mechanic will then check the corresponding relay for the tail lights. Using a multimeter, the mechanic can check the resistance of the relay. If it is not functioning properly, the mechanic will replace it and rewire it to the existing connections.
If the tail lights seems to be functioning properly, but the brake lights are not working, the mechanic should inspect the brake light switch. If the brake light switch is not responding to the brake pedal, the mechanic will remove the old switch, replacing it with a new one. The mechanic should then check to make sure that the brake lights are working and responding to the new switch.
In the case of any repair, the mechanic will make sure that he or she completes the necessary repairs and ensure the functionality of your new components. In the event that an issue with the taillights has triggered an error code, the mechanic will use a code reader/scanner to clear the code and its corresponding light.
How important is this service?
Tail and brake lights are designed to help other drivers see you on the road and if they are not working, you may be at an increased risk for an accident. A police officer may also cite you for not having functioning tail lights in the event you are pulled over. If you notice your tail lights have gone out, or are not working properly, you should stop driving the car and have it inspected by a mechanic.