2005 Corolla Verso Brakes Issue

[DanVerso]

Hello! Happy New Year to all!!!

I'm Dan, the car is an early 2005 Corolla Verso 2.0 d4d with 200.000 kms and I am facing a brakes issue since September '15 with the ABS/VSC/TRC OFF lights coming on (all three of them simultaneously) very often. Techstream reading shows C1246-master cylinder pressure sensor. Symptoms are:

1) car occasionally over-brakes when driving over bumps (on its own will!!) even with very slight pressure on the brake pedal. If this happens in a curve, VSC is also activated, even at very low speed and with car driving in its line

2) ABS kicking in even with no foot on the brake pedal,

3) ABS pump working even on straight line without pressing on the pedal

4) Anti-spin light occasionally comes on when cornering, even at 15mph, on dry road and with no foot on either gas or brake pedals. ABS pump can be heard klicking when anti-spin light is on.

Noticed that brake pedal does not return immediately after releasing it. Brake pedal has normal/usual travel. Also, lights come on everytime when driving over bumps and if I immediately press the clutch and raise revs, lights go off again, only to go back on at the next bump. Symptom appears more often when car is cold, becomes rare when at normal operating temp.

Could it be the actuator on the ABS unit, that has the sensor inside it?

Could it just be an illadjusted brake lights switch, fooling the system?

Would the problem have to do with the brake pedal not returning immediately when released?

Why do lights have to come on over bumps?

Tyres are 2 months old, front shocks, stabiliser rods and ball joints are 2 months old, brake discs/pads are 1 month old. Brake fluid has never been replaced, according to my knowledge.

What would you suggest? Thank you in advance!

[DanVerso]

Hi all,

Update to the issue:

Problem is apparently solved as follows: Connected the car to techstream last night to erase the fault and noticed a calibration code next to the fault report. I thought I'd play around a bit more and tried the "ECU reprogramming" button, where the same fault and the same calibration code reappeared. I pressed the "proceed" button and then shut it down.

Today, after appr. 80 miles and driving over every possible bump on ghe road, expecting the lights to come on again, nothing. None of the previously described symptoms are present, car brakes normally, doesn't overbrake on its own.

The only thing I noticed is that the antispin light comes on occasionally when driving a little bit "spirited" onto motorway ramps with a little bit more speed than one normally would, into curves. No slipping there, but light did flash a couple of times.

Other than that, everything is-so far- normal.

Dan