jd23dr6

My 2014 LS jerks / rocks back in forth during low speed braking.

The feeling is as if the brakes are applied then let go then applied then let go, despite applying constant brake pedal force from the driver. I suspect this is a brake actuator issue.

My question is does this issue affect the transmission of the car? Will it damage transmission?

Can I leave it be until it gets worse or will that damage anything else in the process?

Anfanger

Any error codes? Any vibrations?

jd23dr6

no error codes and no vibration, just a very mild jerking motion at low speed braking.

Anfanger

Have you checked your rotors or entire brakes for any issues? I would still connect Techstream or as advanced alternative and check for error codes.

swfla

iTrader: (1)

Give us some background last date/miles ago brakes and rotors were replaced, was the car braking fine previously, what repair or driving incident precipitated the brake grabbing? Any hard braking or lots of downhill braking? If it's the brakes, it likely won't affect transmission, you're stopping not trying to accelerate. Why do you suspect actuator. I agree w/ Anfanger, any warning lights, have you used a code reader to check for codes? It may just be warped rotors, it can happen for several reasons.

jd23dr6

Car was examined at three places. But no one really knows what do do beyond pads and rotors.

rotor and pads were changed but issue persists.

attaching pictures from the computer scanning test.

jd23dr6

Hello, thank you so much for your help and interest. No warning lights currently on (driven for 300km with no warning lights)

I have attached in a reply above the computer test details.

The car has 230k km (140k miles). I bought the car a month ago and the owner told me there was an issue with the brakes. I had it checked by 3 different mechanics including dealership and no one told me anything about brake actuator. The pads and rotors were changed yesterday and the issue persists that is why i am suspecting actuator.

I don’t know much about how the car was driven as I just bought it but all PPI places reported it was very well kept and maintained at the dealership, with “rock solid engine and transmission”.

the jerking issue is itself is tolerable. What I’m afraid of is damage to something else if nothing is done (transmission can be ruled out?)

Striker223

Perform an actuator offset relearn, I've dealt with this problem before but the opposite direction. If you so much as touched the pedal it would slam on the brakes full power lol!

If your car refuses to relearn your brake actuator is near death, you can also cheat this by removing the controller and using a car with a known good unit to relearn on. I did so with a customer car using my car to relearn his module so he wouldn't have to replace his actuator

Gerf

So the brakes feel and act normally when at higher speeds? sometimes at low speeds an out of round tire will give you a feeling like described.
It's funny you haven't seen a warning light with the accumulator and speed sensor codes being current, did the shop you went to erase those codes?

jd23dr6

Will attempt to do that thank you. If I dont address it, will I be damaging the transmission or any other component from the constant low speed jerking?

jd23dr6

yes exactly, high speed feels normal. Only jerks mildly during low speed.

i dont think they erased anything. But they did change the battery..yes weird that no codes, but the car feels fine and the mechanics told me it was and nothing to worry about.

just had to change cooling fan motor, belt tensioner, fuel pump gasket and head gasket cover.

what do you think? Should I address the issue if it’s still tolerable,
or will it damage something else if left unattended?

Gerf

It wouldn't hurt to do what Striker suggested if you have access to techstream.

Did you burn your new brakes in? there are topics here for directions if you don't know how. If the guy you bought from already knew about it he probably downplayed the issue and maybe you need the actuator/pump replacement.
The only thing it can damage is the whole front end of your car if the brakes fail.

jd23dr6

No didn’t really burn them in. Will do that as well.

Owner didn’t really downplay it, just genuinely did not know what was wrong and shop didn’t as well.

The problem here is lack of intelligent and skilled mechanics. They’ll just throw parts at the problem and pray it helps.

That is why im reluctant to take it there unless issue gets worse. So what I understand from your last sentence, is that no mechanical damage to the transmission or anything else will occur as a result of the low speed perpetual jerking motion, but that there is risk of accident if the brakes fail, correct?

Anfanger

You also got problems with speed sensors (faulty ABS engagement?), I doubt, any re-learn problem will do anything about it. Was the car totaled, probably flooded? Judging by error codes, somebody worked on electrical problems after flooding, accident aftermath etc.

jd23dr6

No major accidents and no airbag deployment, chassis showed no sign of accident. Also car was not flooded, it lived all its life in a dry desert city with barely any rain.