Bad brake light bulb causing computer to go nuts?

Maintenance/Repairs
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1

I was pulling into a parking lot a few days ago and my dash board just lit up. The ABS, brake, and traction control lights came on. I pulled in and parked. The brakes seemed fine but I figured there was at least a problem with a wheel speed sensor or something like that. I ran into something similar except that the car couldn’t get out of its own way when I forgot to transfer the magnetic ring from my old brake drums to my new ones.

I started it up later and there were no lights of any kind. Everything seemed normal.

The car is a 2015 Mitsubishi Mirage DE with a manual transmission. I posted on a forum about these cars and apparently a failing or burned out brake light bulb can cause this type of behavior. I guess that the traction control will engage and the car won’t run right in some examples such as when I forgot to move the magnetic wheel sensor rings. Apparently this is common and led others to think something major was wrong with their braking system when it was just a burned out bulb. One guy also said his situation was intermittent because one of the two filaments in a bulb was burned out and it took him a while to track this down.

I thought about just going and spending a few bucks on new bulbs and being done with it but want to be certain this is really what is wrong. Will there be any codes if no lights on the dash are lit? I know the ABS system uses a separate computer and might need a separate code reader. One of the loaner tool ones for like $400 would likely read this.

Keep in mind that this car is much newer than the rest of my low-tech fleet. Is this normal with newer cars or a quirk of this little car? I am used to a quick blink or getting pulled over by a cop when a light is burned out but not all these dash lights.

2

Why not do that first and see if that solves the problem ?

3 Likes
3

The brake warning lights vary a lot between manufacturers. They also cascade the fault… Brake light on for a burned bulb (or low fluid) soooo… ABS and traction disabled because the brake error. Sometimes stability control and cruise.

Just change the bulb and go from there.

2 Likes
4

I kinda wanted the light to be on so it was obvious if changing the bulb fixes the problem.

5

If a fault code was set it should remain in memory for some time.

6

I am going to have the codes read today and see what comes up.

7

I’m guessing the drivetrain computer thinks there’s a discrepancy between the brake switch (near brake pedal) and the brake lamp circuit. When brake pedal is pressed, that should cause the brake switch to operate, and that should cause the brake lamp to turn on. Computer has access to all those signals. When all that doesn’t happen together, computer thinks there may be some sort of major problem which needs shop investigation.

Most likely, the brake pedal switch or its connector is faulty.