Why Tahoe Third Brake Light Not Working: Here’s Why And Their Solutions

Tahoe’s third brake light’s functioning is crucial as it warns the behind drivers with greater noticeability and clarity. And if there is any problem, the importance of resolution touches the sky. 

So why is Tahoe third brake light not working, and how to resolve it? The factors for the dysfunction of the third brake light are 

• Blown fuse
• Short circuit in the wiring
• Blown bulb
• Damaged brake light switch

Here, one or multiple factors can cause the third brake light problem. However, replacing the faulty units can easily fix this.

In this article, we detail the factors to make you understand. We also inform you of the issue identification process and solutions. So, let’s get into it!

Table: Tahoe Third Brake Light Not Working (Causes And Solution)

Before we jump into details, let’s take a quick glance at the different causes and their solutions to the problem!

Causes	Solutions
Damaged brake light fuse	Replacement of the fuse
Faulty brake light switch	Replacement of the switch
Damaged brake light bulb	Replacement of the bulb
Bad wiring	Repair the wiring

Why Is The Tahoe Third Brake Light Not Working?

As already mentioned, the problem may occur due to a faulty unit or a combination of issues. However, it’s more effective to check periodically to fix it since there is no straight symptom to define any specific problem.

Starting from the fuse box and gradually going through the circuit, reaching the bulb, and lastly, the wiring. Check the steps below to identify the causes and how to fix them.

Step 01: Check Brake Light Fuse

Start by checking the fuse. The brake light fuse is well-marked, often indicating “stop lamps” or related terminology. 

Now, the first thing is to take out the fuse by hand to check its physical condition. If there is any black or burn mark, change it. If there is no sign of damage, follow the testing process below to check the actual status. 

1. Arrange a “Fluck 77” to check the working condition of the fuse.
2. Connect it to a suitable ground point on the vehicle for referencing.
3. Without removing the fuse, carefully establish contact between the metal tabs on the top of the fuse with the probe of Fluck 77. Make sure to establish contact with both metal tabs.
4. If the fuse is functioning correctly, there should be voltage on both sides of the fuse. The meter will display 12.02-12.12 volts.
5. If the reading is far below 12 volts or there is no voltage showcasing, you have to change the fuse. To do so, just take out the fuse and install a new one.
6. Again, check the voltage with the Fluke 77 or any other multimeter after replacing it.

If the light still does not function, go for the next step.

Step 02: Check the Brake Light Switch

If the fuse is working properly, it is time to examine the condition of the brake light switch. First, find the brake light switch under the brake paddle. This switch always remains activated even if the vehicle is turned off. 

In this case, you have to use the Fluke 77 or an LED device. We have already mentioned how to use the Fluke 77 to check the working condition of an electric component. So, here, we will use an LED device to check the switch’s condition. Follow the below process.

1. Take out the switch.
2. You will see there are two wires connected to the brake light switch.
3. Now, connect one wire to the testing LED device and the other wire to a testing pin.
4. The testing setup is now prepared. Establish a connection between the testing pin and the LED light’s pin. 
5. If the LED illuminates, the switch is functioning.
6. If the LED does not illuminate, change the brake light switch. You have to unplug the switch.
7. Remove the brake light switch by removing the connection and extracting the screws and slottings.  Then use your hand to take out the switch.
8. Now, install a new switch and do the reconnection work

Check out this YouTube video to have a clearer picture: 

However, if the brake light switch is working, you have to go for the next step to identify the issue.

Step 03: Check the Brake Light Bulb

As your car gets older, its brake light bulb’s capability decreases. It might not shine as brightly as before. In this case, even if the light is working, the behind drivers won’t be able to get notified. 

Additionally, there is always a significant amount of chance that the brake light bulb becomes dysfunctional. Both situations demand a change of the bulb. Below is the stepwise guide to changing the bulb.

1. Take out the coverings of the third brake light.
2. Remove the bulb.
3. Examine the part around the bulb. If there are any cracks, the bulb won’t work anymore.
4. Now, focus on the little wire inside the bulb. The presence of little wires inside the bulb indicates that it’s time to replace the bulb. Take out the old bulb from the holder and install a new one.
5. We suggest you change all three bulbs at this time. It will save you time and effort if the 2nd or 3rd bulb gets damaged in the near future.

Step 04: Check For Bad Wiring

Well, if any of the above-mentioned issues are not present, certainly there is a wiring problem. It is time to check the third brake light wirings on your Tahoe. The following is a DIY process.

1. Check the entire length of the wiring harness that connects the brake switch to the third brake light bulb(s). 
2. Look out for any trouble, such as frayed or damaged wiring. If you can find any, repair that part of the wiring.
3. Make sure that the wiring has a good ground connection by checking for any loose or disconnected grounds.
4. Thoroughly inspect the wiring for any signs of short circuits or cracks. And change those damaged wires.
5. Finally, check the wire connection at the third brake light’s input point. Check if the input point is getting power. If there is no power, check the whole wiring again.
6. If still you cannot find any wiring issues, contact a professional.

Approximate Cost of Each Repair

The table below contains the associated costs of the replacement parts when you fix it yourself.

Parts	Cost
Fuse	$10-$15
Switch	$18.95-$25.90
Bulb	$5-$21
Wiring	$79-$120

Dealing with brake light issues on a Chevrolet Tahoe can be frustrating. However, brake light malfunctions aren’t restricted to just one model. There are instances when drivers notice both the brake light and ABS light on, coupled with a non-functional speedometer. Such combined malfunctions can indicate deeper electrical or sensor-related problems. Additionally, if you’re someone who frequently tows trailers, you might come across situations where the left turn signal and brake light aren’t working on the trailer. Each vehicle and model has its unique set of challenges, but understanding the common threads can be immensely helpful in troubleshooting.

FAQs

Here, we answer some of the most common questions regarding this topic.

Final Words

So why is the Tahoe third brake light not working? The issue with the third brake light usually occurs due to problems in the brake fuse, switch, bulb, and wiring. The DIY methods explained above are effective in addressing each of these problems.

However, if you are not a professional or lack knowledge in terms of the car’s mechanism, we suggest you seek professional assistance. A general garage can solve this problem. But, it is better to visit an authorized workshop of Chevy to get added advantages.