Replacing a Brake Light Bulb Video
The brake lights
on your car are designed to warn the drivers behind you that your car will be slowing
down or stopping. Most cars are equipped with three brake lights, one on either
side of the rear of the car and one on the upper level deck lid or roof line. The
third light or Cyclops light was inter-graded into the manufacturing process as
an additional safety device in the early 1990's. A brake light system in most cases
is a basic electrical system
involving a simple positive and ground system controlled by a
brake light switch activated
by the driver.
In all car electrical systems a fuse
is used to protect the brake light electrical circuit. Most cars are equipped with
a switch that is connected to the
brake pedal. The brake light
switch rests in the open position and closed (electrical contacts connected) when
the brake pedal is activated. The brake light switch is easily adjustable by moving
the main switch housing within the metal bracket that holds the switch. Some brake
light switches have additional functions such as the cruise control brake sensor
and ignition key interlock function which do not affect the brake light function.
Brake Lights
A little know fact is the red brake lens can melt and distort when the brake
lights are kept on for an extended amount of time. This heated condition can also
negatively affect the brake light bulb holder as well. Never allow the brake light
to stay on overnight. There is one major difference between American and Japanese-European
auto manufacturers. The American car makers have incorporated the brake light circuit
into the turn signal system, and vice versa.
The Japanese and European manufacturers design the brake and turn signal electrical
systems separately. For this reason troubleshooting the same problem will be slightly
different from the two different styles of manufacturing. We have listed "American"
and "Japanese-European" separately in the page below. We also include procedures
for one to all brake lights not working. One other condition that we will cover
in this section is how to repair a brake light bulb that is dull or flickering.
Troubleshooting Procedures - Read Completely Before Beginning
(American Car) All Brake Lights Not Working
Check System
Fuse - A fuse is used to protect the brake light circuit from amperage
overload. If the fuse has failed it will not allow the electrical current to continue
to the brake lights. To check the fuse, first locate the brake light system fuse
in the fuse panel which is either under the dash or under the hood in the power
distribution center. Connect the test light to a ground like an engine or dash bracket
and turn the ignition key to the "on" position. Using the test light probe both
sides of the fuse. If the test light illuminates on both sides the fuse is okay
continue onto the next step. If one side of the fuse illuminates the fuse has failed
and needs to be replaced. If the fuse fails as soon as it is replaced or when you
apply the brake pedal the brake light electrical circuit is shorted to ground. Rarely
a system short can occur, a car repair manual is needed to find the wiring schematic
for the brake light circuit. Once the brake light wiring has been located inspect
and repair as needed.
Check Brake
Light Bulbs - All cars have three brake light bulbs that create the
brake light illumination affect. If all of these brake light bulbs fail no brake
light operation will occur. I know what you're thinking, you might say all three
brake lights at once? But in reality one brake light went out at a time and you
did not notice. People only tend to notice something when they almost run into the
back of your car to help persuade them to inform you the brake lights aren't working.
Remove any of the brake light bulbs to confirm the bulb is okay or burned. After
the bulb has been removed inspect the filament and replace if failed. If the brake
light bulbs are okay continue to the next step.
Checking the Brake
Light Switch - A control switch is used to connect the brake light
electrical circuit. This switch is located near the brake pedal lever. Basic switches
have just two wires, power in and power out to the turn signal switch. Use a test
light that is grounded and with the key in the "on" position test for power at one
side (wire) of the switch, then press the brake pedal while testing the opposite
side (wire). It should illuminate the test light, if electrical power is connected
through the switch go to the next step. If no power is detected through the switch
the brake light switch has failed and replacement is required. If your car is equipped
with more than two wires integrated into the brake light switch a car repair manual
is needed to locate the proper brake light circuit wiring.
(American Car) Both Lower Brake Lights Not Working
Check Brake Light Bulbs
- All cars have three brake light bulbs that create the brake light illumination
affect. If the lower two bulbs fail no lower brake light operation will occur. I
know what you're thinking, you might say two brake lights at once? But in reality
one brake light went out at a time and you did not notice. People only tend to notice
something when they almost run into the back of your car to help persuade them to
inform you the brake lights aren't working. Remove either of the brake light bulbs
to confirm the bulb is okay or burned. After the bulb has been removed inspect the
filament and replace if failed. If the brake light bulbs are okay continue to the
next step.
Checking the Turn Signal
Switch - Most American cars are designed to have the brake light switch
wiring inter-graded into the turn signal switch. Because the brake light bulb and
the turn signal bulb are one and the same the turn signal switch interrupts the
brake light circuit and installs the blinker signal circuit when the turn signal
switch is activated. If this switch fails it will not allow the brake light signal
through to the brake light wiring. To test for this condition a car repair manual
is needed to test incoming and outgoing electrical current. If brake light switch
power is present at the turn signal switch but not at any outgoing brake light wires
the turn signal switch has probably failed.
(American Car) One Brake Light Not Working
Inspect Brake Light
Bulb - The number one reason for a brake light operation failure is
a failed brake light bulb. To check this condition access the bulb by removing the
rear cover located in the trunk or rear compartment. Some cars allow you to remove
the entire brake light lens to retrieve the brake light bulb. Once the bulb has
been removed inspect the bulb filament. If it looks broken or if the bulb is smoked
the bulb needs to be replaced. If you have replaced the bulb but it still doesn't
work remove the bulb. With the key in the "on" position have someone hold their
foot on the brake pedal and use a grounded test light to careful test the terminals
inside the light socket.
One of the terminals should illuminate the test light. (Note: Do not touch the
outer metal ring that holds the bulb in place for it is grounded and can blow the
system fuse if connected to the inner terminals.) If the test light illuminates
reinstall the brake light bulb. While the brake pedal is depressed test the outer
metal ring that holds the bulb, if power is present the ground lead from the light
socket is bad. If the outer ring does not illuminate the bulb has failed and replacement
is required.
Scan BCM for Trouble Codes - Some cars are equipped with a body control
module or BCM this on-board computer controls and lighting signals and can malfunction
not allowing the electrical current to continue to the brake light circuits. This
condition is rare but it can happen. If you have performed all of the tests above
and all results are positive scan the BCM for trouble codes if no codes are present
try replacing the BCM.
(Japanese/European) All Brake Lights Not Working
Check System
Fuse - A fuse is used to protect the brake light circuit from amperage
overload. If the fuse has failed it will not allow the electrical current to continue
to the brake lights. To check the fuse, first locate the brake light system fuse
in the fuse panel which is either under the dash or under the hood in the power
distribution center. Connect the test light to a ground like an engine or dash bracket
and turn the ignition key to the "on" position. Using the test light probe both
sides of the fuse. If the test light illuminates on both sides the fuse is ok continue
onto the next step. If one side of the fuse illuminates the fuse has failed and
needs to be replaced. If the fuse fails as soon as it is replaced or when you apply
the brake pedal the brake light electrical circuit is shorted to ground. Rarely
a system short can occur, a car repair manual is needed to find the wiring schematic
for the brake light circuit. Once the brake light wiring has been located inspect
and repair as needed.
Check Brake
Light Bulbs - All cars have three brake light bulbs that create the
brake light illumination affect. If all of these brake light bulbs fail no brake
light operation will occur. I know what you're thinking, you might say all three
brake lights at once? But in reality one brake light went out at a time and you
did not notice. People only tend to notice something when they almost run into the
back of your car to help persuade them to inform you the brake lights aren't working.
Remove any of the brake light bulbs to confirm the bulb is ok or burned. After the
bulb has been removed inspect the filament and replace if failed. If the brake light
bulbs are ok continue to the next step.
Checking the Brake
Light Switch - A control switch is used to connect the brake light
electrical circuit. This switch is located near the brake pedal lever. Basic switches
have just two wires, power in and power out to the brake light wiring system. Use
a test light that is grounded and with the key in the "on" position test for power
at one side (wire) of the switch, then press the brake pedal while testing the opposite
side (wire). It should illuminate the test light, if electrical power is connected
through the switch go to the next step. If no power is detected through the switch
the brake light switch has failed and replacement is required. If your car is equipped
with more than two wires integrated into the brake light switch a car repair manual
is needed to locate the proper brake light circuit wiring.
(Japanese/European) Both Lower Brake Lights Not Working
Check Brake Light Bulbs
- All cars have three brake light bulbs that create the brake light illumination
affect. If all of these brake light bulbs fail no brake light operation will occur.
I know what you're thinking, you might say both brake lights at once? But in reality
one brake light went out at a time and you did not notice. People only tend to notice
something when they almost run into the back of your car to help persuade them to
inform you your brake lights aren't working. Remove either of the brake light bulbs
to confirm the bulb is okay. After the bulb has been removed inspect the filament
and replace if failed. If the brake light bulbs are okay continue to the next step.
Checking Brake
Light Control Module - Some Japanese cars have a brake light control
module that can malfunction causing both lower or the center brake light to fail.
To check for this condition locate the module which is usually near the rear seat
on the driver's side. Then test the incoming power feed from the brake light switch.
If incoming power is present without outgoing power replace the brake light control
module with new to recheck system.
(Japanese/European) One Brake Light Not Working
Inspect Brake Light
Bulb - The number one reason for a brake light operation failure is
a failed brake light bulb. To check this condition access the bulb by removing the
rear cover located in the trunk or rear compartment. Some cars allow you to remove
the entire brake light lens to retrieve the brake light bulb. Once the bulb has
been removed inspect the bulb filament, if it looks broken or if the bulb is smoked
the bulb needs to be replaced. If you have replaced the bulb but it still doesn't
work remove the bulb. With the key in the "on" position have someone hold their
foot on the brake pedal and use a grounded test light to careful test the terminals
inside the light socket. One of the terminals should illuminate the test light.
(Note: Do not touch the outer metal ring that holds the bulb in place for it is
grounded and can blow the system fuse if connected to the inner terminals.) If the
test light illuminates reinstall the brake light bulb. While the brake pedal is
depressed test the outer metal ring that holds the bulb, if power is present the
ground lead from the light socket is bad. If the outer ring does not illuminate
the bulb has failed and replacement is required.
Scan BCM for Trouble Codes - Some cars are equipped with a body control
module or BCM this onboard computer controls and lighting signals and can malfunction
not allowing the electrical current to continue to the brake light circuits. This
condition is rare but it can happen. If you have performed all of the tests above
and all results are positive scan the BCM for trouble codes if no codes are present
try replacing the BCM.
Brake Lights Dull or Flickering - All Cars
Dull or Dim Brake Light Repair - If your car
has a dull or dim brake light it is dangerous to you and other drivers. A dim brake
light is a mystery to most people because the bulb is working, just not correctly.
First confirm a new and correct brake light bulb has been installed. Next, turn
the ignition key to the "on" position and have a helper depress the brake pedal.
With the bulb installed touch a grounded test light to the outer bulb holder ring.
If the bulb brightness changes the bulb socket ground has high resistance and needs
to be repaired or replaced.
Flickering Brake Light Bulb Repair - A flickering brake light
bulb can be very distracting and annoying. A brake light flickers because the power
or ground is being obstructed momentarily. The most common cause for this condition
is a loose fitting bulb socket. To check for this condition remove the brake light
bulb in question, while a helper hold their foot on the brake pedal move the bulb
around slightly in the socket. If the bulb flickers replace or repair the bulb socket
as needed to regain proper brake light bulb operation. If the brake light bulb socket
tests okay wiggle the brake light fuse and wiring at the brake light bulb socket,
brake light switch and turn signal switch (American cars). If the brake light bulb
flickers repair the component or wiring as needed.
Preferred Procedure
- Always replace brake light bulbs with manufacturers recommend replacement
bulbs. If you cannot find the correct replacement bulb part number consult an
Auto Part Store for additional manufacturer information.
Common Problems
- When brake light bulbs are replaced with the incorrect bulb causing no or
dim brake light operation
- If the brake lights stay on continuously it could mean the brake light switch
has failed or an adjustment is needed
If further technical assistance is needed, our certified car repair technicians
are ready to answer your car questions.
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