Fairly rare/intermittent ABS+Stability control light (2013 Auris, manual, petrol)

[Tadas`]

Hello,

Model: 2013 Auris, manual, petrol.

From time to time I get ABS and Stability control warning lights. I don't drive too much, but it also does not happen that often as well. From what I remember it's always in a start/stop intensive slow moving city traffic. Sometimes it starts quietly, sometimes it starts with some unusual mechanical noises from the front (I guess the ABS module/pump). I also sometimes feel brake pedal dip a little.

I first observed it ~1 year after purchase. Possibly related: MOT garage mentioned rear brake pads worn, so I went to an official Toyota service and got brake pads + rotors replaced (recommendation from them). I first observed the issue some time after this service.

Usually it's not huge deal. As I mentioned - it happens in slow moving stop/start traffic. But sometimes accelerator pedal becomes unresponsive (now that gets my heart rate up, I'm a fairly inexperienced driver).

The issue goes away after power off and on again. And most of the time it does not show up again on the same day.

Question: does Toyota "computer" log these things? I got a very basic obd2 reader and it shows nothing. But if I take it to Toyota service, can they get any kind previously logged failure codes or something? Is it worth taking it to service since the issue is rare and hard to reproduce?

Many thanks for ideas 🙂

[TonyHSD]

Hi, it will depend of the obd 2 adapter and software, I had recently issues with speed sensor on one of the wheels and was able to diagnose using a Carista adapter and their app(paid version). Having a problem with brakes it’s not a something that you should ignore for sure, this is the most important system in your car. My advice is to get proper diagnostic, Toyota tech should be able to scan and tell you the trouble codes stored in the car ecu. Can be anything from failing speed sensor to brake booster or abs pumps, diagnostic it’s your first thing to do. 
Good luck 👍

[loz8]

Yes,good luck.   I've only spotted it twice,at the bottom of a hill where the road is rough and going around large traffic island probably fuel spillage.

[Tadas`]

So my long story of this intermittent issue continues.

I now have code reader (Topdon bluetooth thingie). From body control section it reads:

C1426 : Stop Switch OFF stuck
C1246 : Master Cylinder Pressure Sensor

I did reset multiple times to check how/when they come back. One time I found C1426 only. Now.. According to this page state of stop lamp switch is used in fault detection for the master cylinder pressure sensor. It's almost as if the switch could be problem.

[Bper]

You mentioned the accelerator peddle was unresponsive this could be the peddle sensor and I would get that checked out ASAP as the last thing you want is for this to let you down.

As Tonyhsd pointed out get a proper diagnostic on the brakes but do this on both problems and do not ignore these🤕.

[flash22]

Change the brake light switch, its more than likely throwing the pressure code as it thinks the brake released, but the pressure sensor is seeing pressure

[Tadas`]

Right. So.. Couple days ago I learned that the scanner can also record all kinds of system state parameters.

As I mentioned the issue does not show itself often. And lately I haven't seen it until today. After couple of hours driving got a few "Vehicle Stability Control" light blips. Stopped, parked and started recording "Stop Light Switch" and "Master Cylinder Sensor" values. After driving for 10min got couple more blips + longer 2-3 seconds of blinks and beeps.

Now for the results of recording:

Normal operation example - press brake pedal -> switch state goes from OFF to ON (yellowish line) and sensor voltage increases (blue line):

Then.. Somewhere in the record I find couple unusual blips:

Brake is not being pressed - sensor value shoots up.

And then there's this (must be the cause of the 2-3 seconds of bleep series):

I guess it's a reasonable guess that the pressure sensor may be faulty.

Don't think I want to make any attempts at changing it myself, but hey.. It's a fun debugging/troubleshooting adventure before going to a garage.

[AisinW]

What I will do, I go to a trusty mechanics who have a long experience with hybrid. Otherwise, find the best dealership service department and ask for detail diagnostic. From Prius USA NHTSA website, we know that there is a campaign of brake booster assembly replacement for 2010-2014 Prius. Now it lasted up to 10y/150k miles, 1 year ago was unlimited miles. 

[flash22]

iirc pressure sensor is in the abs pump

Edit. when was the brake fluid last changed ?

it looks like the abs has an issue and needs recalibration/rebuild

2 hours ago, AisinW said:

What I will do, I go to a trusty mechanics who have a long experience with hybrid. Otherwise, find the best dealership service department and ask for detail diagnostic. From Prius USA NHTSA website, we know that there is a campaign of brake booster assembly replacement for 2010-2014 Prius. Now it lasted up to 10y/150k miles, 1 year ago was unlimited miles. 

Its a Manual Petrol car so will have a conventional servo/master setup

[AisinW]

My bad, it is a good news then. Much cheaper to get the parts.