About 4 months ago I was driving and was slowing down at the light when I felt a hard jerk like my brakes locked up. I managed to pull over and turn the car off. Turned back on and it drove good until last week where it did it again.

Took to a mechanic and since my car isn't throwing codes or CEL, they said it could be the front wheel sensors that's causing this sudden brake when driving. They installed one of the sensors that they claimed was corroded and it did it again.

My mechanic suggested to switch out the other wheel sensor but obviously can't guarantee it to be fixed.

No VSA lights on as well. Any help is appreciated. Thank you

 

Do you feel the vibrations in the brake pedal when braking when problem occurs? You should also hear loud noise from the front (as electric motor for abs will turn on when abs activates)

Sensors are easy to check - have a scan tool that can read speed of all sensors, make it show the data as graph, and go for a drive. One that is out of order (like dropping the signal or showing different speed than the rest) is the faulty one. Erratic reading might also be caused by the encoder in the wheel bearing (sometimes bearing can have enough play to cause the wrong reading).

ABS will rarely lock / overbrake. It's more likely to under-brake. Especially when sensor it at fault.

Locking/dragging brakes are most often caused by bad caliper / brake hose.

 

Could very well be a stuck caliper. But your mechanic probably checked for that.

 

I dont feel any vibration at all. Car has been driving good until this. he mentioned during the diagnostic that the abs module pulled a code but he recalibrated it and still no luck

 

Without knowing the code we have nothing to go on. Also I have no idea who is right or wrong: You describing the symptoms, mechanic throwing sensors at the car, maybe nobody? You'd be surprised on how people describe some noise/behavior and then when I get inside the car it's nothing like that.

I suspect mechanic has no idea what's going on, but maybe the problem is so intermittent that he couldn't replicate the symptoms to he guesses based on old codes or something.

 

That's the thing. My car is throwing no codes so at this point the mechanic is just guessing because no codes. I let the mechanic drive the car while I was in it and it did it so he knows exactly what I'm talking about. He has buddy's at the Acura and Honda dealership as well and they are confused as well

 

Does the brake pedal return normally when problem occurs? Will problem go away on its own or you must restart the car to fix it? Try pumping the pedal when it happens.

 

yes the brakes return. last time i drove it, it did once then nothing for about 10 minutes. i parked got back in the car and it did it as i was pulling out and I couldnt give it much gas because it did it again. luckily i was able to coast to a nearby mechanic

 

Are you sure there is not a hard jerk because the transmission isn't engaging?

 

i dont think its that. the two shops i took it to would've discovered that dont u think.

 

Perhaps the caliper slide bolts are crusty/dirty.loose??

 

I am assuming automatic? How many miles?

 

Considering they haven't identified the issue, anything is still on the table at this point.

In the TL, the only thing that "should" be able to activate the brakes electronically is related to traction/stability control. If that system were active, it "should" have blipped the traction control light on the dash. I don't even know if that system can even apply the brakes that hard?

Now if something mechanical is broken, maybe sticking caliper, collapsed brake line hose, borked axle, broken teeth on a gear in the trans, or the ABS module is on the fritz (but this should have thrown a code...should have). I am poking at the transmission topic because you said you needed to "coast" to the mechanics. That implies to me you didn't have power, not that you had over active brakes.

It is a hard stop? Does the car lurch one direction or the other? Do any of the tires squeal/screech? Does just one tire screech?

As I typed broken teeth in the trans....this has me thinking. I broke the gears on the diff on a previous car, and it caused really really odd binding in the transmission like you described. Never in a straght line, but when turning, it felt like I was jabbing the brakes. Not sure I have ever heard of that on TL....but just something I experienced in a completely different platform.

 

yes automatic and 184k miles