Easy step by step repair guide on how to fix automotive brake lights, all lights
out or a bulb that is dull or flickering, this article pertains to most non-LED
Difficulty Scale: 4 of 10
Tools and Supplies Needed
- Test light or voltmeter
- Safety eyewear and gloves
- Small screwdriver set
Begin with the vehicle on level ground, parking brake set while in park using
a basic set of tools while wearing protective eyewear and gloves.
If a singular brake light bulb has failed visit -
, if you have replaced the bulb and its still not working, is
dull or flickers, or more than one bulb is out you're in the right place.
All Brake Lights Out
New Brake Light Bulb
Step 1 - If the system brake light fuse has failed
the brake lights will not operate. Visit -
Replace Brake Light System Fuse
Step 2 - When a brake light switch fails it will
cause the brake lights not to operate, with the key in the "ON" position, use a
test light and a
to check for incoming and outgoing power. If power is present
with no outgoing power while the pedal depressed, the switch has failed. Visit -
Test Light Instruction
Step 3 - American vehicles incorporate the
turn signal switch into the brake lights, when this switch fails it can cause both
or one lower brake light not to work, access the switch wiring harness using a
and test light to confirm the failure.
Step 4 - Some vehicles are designed with a lighting
control module which can malfunction causing both lower or the center brake light
to not work. Using a
Turn Signal Switch
and test light check the incoming power feed from the brake light
switch, if incoming power and trigger signal from the brake light switch is present
without outgoing power to the brake lights, replace the lighting control module.
Dim or Not Working
- Remove the bulb in question and confirm
the correct unit has been installed, next turn the ignition key to the "ON" position
and have a helper depress the brake pedal and hold. Using a grounded test light
carefully probe the socket terminals/wiring, one should have power. If no power
is present and the other two bulbs are operating the wiring has failed to that particular
- If the bulb socket ground has failed
the bulb will not work, using a pick or other small object clamp it to the test
light and use the power which you just tested for to check the ground circuit, if
the test light doesn't light up, the ground circuit is bad.
Step 3 - A brake light flickers because the power
or ground is being obstructed momentarily, the most common cause for this is a loose
fitting bulb socket. Remove the bulb in question, while a helper holds down the brake pedal
move the bulb around slightly in the socket, if the bulb flickers replace or repair
the socket as needed, also wiggle the wiring.
Most American cars are designed with the lower brake light circuit wiring incorporated
into the turn signal switch where 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 circuit when the switch is activated. Japanese and European
auto makers design separate brake and turn signal electrical systems.
A brake light system in most cases is a basic electrical system involving a simple
positive and ground system controlled by a switch which rests in the open position
and closes (electrical contacts connected) when the pedal is depressed.
A brake lens and socket can melt and distort when the brake lights are kept on
for an extended amount of time, avoid allowing the brake light to stay on overnight.
- Replace brake light bulbs with manufacturers recommend replacements.
Article first published 2016-04-27