Vehicles have several critical features for improving road safety. Among these features are the rear lights – brake, tail, reversing, rear fog, and turn signal lights – mounted on the back of automobiles. All these lights must work in unison to ensure road safety, particularly in the dark.
However, these lights can malfunction and trigger a rear light failure warning light on the dashboard. This warning light may worry and frustrate you if you’re not a car expert. So, what does this warning light mean, and how can you address it?
Herein, I detail everything you may want to know about the rear light failure message. I’ll provide the most possible causes and the best ways you can resolve this problem.
Answer: Meaning of Rear Light Failure Warning Light
The warning light for rear light failure indicates your vehicle has one or more malfunctioning rear lights. If there’s an issue(s) with the rear lights affecting their normal operations, this light will appear on the dash.
Several issues can trigger this warning light. Some include a malfunctioning bulb, a bad sensor, wiring problems, or too much humidity around the rear lights.
It’s essential to address this problem as soon as possible to ensure the safety of other drivers and road users.
Answer: Causes of Rear Light Failure Warning
Below are the common causes of this warning light and what to do about it. Some issues are easy to fix at home, while others may require the skills of a mechanic.
Malfunctioning Rear Light Bulb
A bad rear light bulb will cause the warning light to show on the dashboard. Generally, rear light bulbs last around 5-6 years or 40,000 miles.
However, driving habits, such as excessive braking, can cause these bulbs to go bad sooner. It’s worth noting that LED rear lights in newer car models will last more than 12 years.
The rear light bulb can blow out due to electrical shorts and stop working. You can check the filament in the bulb to see if it’s broken. The bulb may also appear grey-black on the inside.
Besides, a loose rear light bulb may function intermittently and cause the warning light. The sensor will detect that the bulb is no longer working as it should and inform the ECM. As a result, the ECM will turn on the warning light on the dash.
Start by removing the light assembly. In this case, you’ll need to loosen the screws and bolts using a screwdriver and a wrench. Inspect the rear light bulbs to see if any are loose. You can tighten any loose bulb by turning it clockwise. Then, replace any damaged rear light bulb.
Bad Sensor
Your vehicle has several sensors that communicate with the onboard computer. Some include hydraulic, engine, rear light, and fuel sensors. They provide information regarding your vehicle’s operations.
A bad rear light sensor doesn’t provide accurate data about the rear lights. When the ECM detects the incorrect input about the rear lights, it may cause the rear light failure warning light.
Several issues may cause the rear light sensor to malfunction. Some include dust, contaminants, everyday wear, shocks, and vibrations. Locate the problematic sensor with the help of your vehicle’s owner’s manual. Clean the sensor if it looks clogged, or replace it if damaged.
Note: When you replace the rear light sensor, you must reset the ECM to ensure it works with the new sensor. You can do this by disconnecting the battery for 15-20 minutes. Then, discharge the electrical components by pressing the horn button and turning on the lights.
Faulty Wiring and Connectors
The rear lights, ECM, and sensors use wires and connectors to transmit signals. Over time, the wiring and connectors can wear out, get damaged, or become loose and fail to transmit signals. This issue may trigger a rear light warning message on the dash.
Diagnosing wiring and connection issues can be challenging, so allow a professional to do the work. Your mechanic might use an OBD-II scanner to find the defective wires and connectors. Alternatively, they can use a wiring diagram to locate and examine the faulty wires.
Fixing issues with the wiring may involve securing the connections or replacing worn or broken wires. Dirty or corroded wires and connections need cleaning with sandpaper, rubbing alcohol, or a contact cleaner spray.
Blown Fuse
The light fuse protects the rear light bulbs and wiring against overcurrent. Without this fuse, the rear lights and wiring would often get damaged.
In the case of an overcurrent, the fuse blows out to prevent more current from flowing to the rear lights. This ensures the lights stay in good condition despite the electrical surges.
If there’s no current going to the lights, the sensors will detect this problem and communicate with the ECM. As a result, the ECM will turn on the warning light on the dash.
Replacing the blown fuse can help resolve this issue. Start by locating the light fuse in the fuse box with the help of the owner’s manual. Inspect the fuse to see if it appears blown, or test it with a multimeter. Then, remove the bad fuse with a fuse puller and install a new one.
Note: The new fuse must be the same size, amperage, and rating as the original fuse.
Excessive Humidity Around the Rear Lights
The plastic housing surrounding the rear lights protects the bulbs and wiring against humidity. However, humidity may seep through the openings if this housing compartment is improperly installed or loose.
Humidity is bad news for the electrical system around the rear lights. It can damage the wiring and connections or cause electrical shorts. If the sensor detects any of these issues, you’ll see a warning light for rear light failure on the dash.
Remove the plastic housing of the affected rear lights and wipe the moisture away with paper or microfiber towels. Reinstall the plastic housing and tighten the screws and bolts. You may also want to use sealant around the edges to prevent this issue from recurring.
If the housing compartment has cracks, replace it.
Question: Can You Drive With a Rear Light Failure Light on the Dash?
Your vehicle is drivable despite having the rear light failure light on the dashboard. This warning light signifies malfunctioning rear lights, so it doesn’t affect how you drive the vehicle.
However, driving with defective rear lights is a traffic violation. You may lose your license, get a criminal record, or face severe penalties. Besides, driving with malfunctioning rear lights poses a safety risk to other road users.
Wrapping Up
The rear light failure warning light appears on your vehicle’s dash to indicate issues with the rear lights. These lights may malfunction due to a defective sensor or excessive humidity in the plastic housing. Furthermore, electrical problems such as damaged wiring, loose connections, or blown fuse might be to blame.
Determine the root problem and fix it to restore the rear lights’ functionality and clear the warning light. If you encounter challenging rear light issues, hire a reputable mechanic to troubleshoot them.