How to Fix Brake Light Failure on a Mitsubishi Lancer

Last Updated on 2025-09-08

Brace yourself because I have some good and bad news. The problem with your Mitsubishi Lancer seems like an easy fix, considering I have seen that problem many times before. Since the brake lights are not working now, I would suggest checking the fuses. If the fuses do happen to be working, concentrate on the switches now for troubleshooting purposes.

While you’re pondering over that information, I’ll pop the hood and work on my coffee whilst helping you diagnose the issue like a classic Sunday repair session.

Step 1: What Exactly’s Going On?

I have one main question for you, What seems to be the issue at hand? From my prior experience, the majority of them tend to be simple fixes. About thirty percent of them can turn complicated, but even in that scenario, we would still reach somewhere eventually. While we figured everything out on what needs to be done, I can use all of my experience and help guide you step by step through the process. No what ifs, lets try a handy approach and work rather than focus on filler.

Here is my most important question for you: What would you consider working? Regarding the lights, are all three of the units malfunctioning? Is only one of them ineffective? Do the tail lights remain functioning along with the headlights?

Another piece of information I would advise checking is the third tail light situated at the rear window or the tail as it is commonly referred. If the third light functions normally and the other lights do not, then we can conclude that the comparison will rest moment of clarity we do have. One other important thing to mention is that those bulbs in the vehicle are generally fitted with dual filaments, where one filament is used for tail light while the other is associated with the brakes.

Step 2: Pop the Trunk — Check the Bulbs

Let's move on to the next step. Please pop the trunk, remove the tail light assembly cover, and take the bulbs out. If they are halogen, check if the filament is burned out or broken, along with the bulb itself. If it’s LED, recheck the installation — the LEDs need to be in the right way. If they’re put in the wrong way, they won’t light up whatsoever.

The rule of thumb is, 'if it looks good, check it against a known working unit'.

Pro Tip: Brake light bulbs for Lancer models are typically of the 7443 variety. In any case, don’t assume so. Take the old one, and bolt it for a new one in the parts shop; or reference the owner's manual before reassembling.

Step 3: Check the Fuse — It’s Too Easy to Skip

Many skip this step, going right to switching the circuits out or tearing apart half their interior. That's wild.

Locate the fuse box; it will either be under the dashboard or in the engine bay. Look for the section that says 'Stop Light' or 'Brake.' Even if it appears fine, swap it out for a new one. It's more affordable than you think, and with certain fuses, you can't tell if there is a micro crack or if it's blown until there is a load.

If it blows a second time right away? That means we have an underlying short somewhere. Don’t keep replacing the fuse; it’s not the solution.

Step 4: Evaluate the Brake Light Switch

Okay, now shimmy underneath the dash and glance upwards brake pedal. Every single time you push the brake pedal, that little toggle switch gets pressed down.

If it is not fitted securely, is crooked, or is just plain broken — your brake lights will not work.

Here’s how to test it:

• Unplug the connector.

• Use a multimeter or test light to check for voltage when the pedal is pressed.

• If nothing happens? Swap it out.

They don’t cost a lot, typically less than $20, and can be thrown away quite easily. Replacing them does not even require any special equipment, only a bit of willingness and a flashlight.

And make sure you keep an eye on the plastic stopper situated between the pedal and the switch. If it fractures (which happens quite often in older Lancers), the switch may never turn on.

Step 5: Check the Wiring — Yeah, This One’s a Pain

If everything checks out with the switches, fuses, and bulbs, you will need to trace the wiring next.

Remove the tail light connector and visually inspect the wiring.

• Any green corrosion?

• Burn marks?

• Loose or frayed wires?

The wires can break beneath the protection, especially on older vehicles with constant trunk use and the insulation. Squeeze the harness and check for cracks and deformations.

If the connector is loose, you can keep it secured temporarily until you replace the connector using a zip tie, hot glue, or other material.

Step 6: Time to Grab the Multimeter

Still no luck? Let’s go deeper.

Get your multimeter, set it to DC voltage, and check the brake light socket while someone presses the brake pedal.

• No power? Trace it back toward the switch.

• Power but no light? Bad ground or socket.

No matter how good the rest of the circuit is, a weak or corroded ground wire will mean nothing since it won’t light up. Make sure that all the contacts are clean, check for rust, and make sure that everything is tight.

Step 7: Still Stuck? Call in Reinforcements

Well, buddy. If you've tried everything — bulbs, fuses, BC switch, wires, multimeter — and your brake lights are still not working? Perhaps it’s time to get a shop to check for you.

Potentially, there’s a more serious electrical problem or an issue with a body control module. Most DIYers don’t have the scan tools for that, and I’m happy to excuse you if it's time to wave the white flag.

Final Words from the Garage

Candidly speaking, diagnosing and fixing brake lights on a Lancer should not take an unreasonable amount of time, but like everything else, it will require some measure of patience. Most likely issues will be a bulb, fuse, or switch, which are common.

Just keep in mind: not having brake lights means that when you hit the brakes, the vehicle behind you becomes invisible. That’s not exactly a risk worth taking. So fix it now before getting tapped in the chassis base, or worse, losing control.

Oh, and while you're at it, check the license plate lights after you fix them. Don't you think it seems reasonable?