Solid brake pedal, abs & eps light

[RobDav99]

Hi all had a terrifying experience in the octavia mk2 today. 

 

Came to a junction and brake pedal was rock solid and applied no brake effort to the brakes. 

Had to use the handbrake to slow down! 

After that brakes have gone back to working fine and got us home fine. 

Abs and traction control light came on earlier in the journey and they have come on intermittently during journeys for the last few days byt brakes had been working fine. 

 

Anyone ever seen/heard of this before? Whats it likely to be? 

 

Obviously not going to risk driving the car again until it sorted. 

 

I've got a vagcom lead somewhere so I'll dig that out and plug it in and read codes afterwork. 

 

Any advice/help would be appreciated. 

Thanks Rob 

 

[RobDav99]

No one have any thoughts? I've had a look around engine bay and vac pipes all seem ok. 

 

Abs light is on. 

 

Brakes working fine up and down the drive, not tried out on the road again yet. 

[Guest]

A solid pedal has to indicate loss of servo assist.

 

I have no experience of a faulty tandem pump other than a loose vacuum nipple on the pump and split rigid hose to the servo resulting in partial/inconsistent vacuum.

 

Poor/inconsistent braking was experienced before I corrected the snag.

 

ABS warning could be a coincidence, pointing to a loose electrical connection, bad wheel sensor/ring.  Then again it may be indicative of an ABS pump failure.

 

Only a diagnostic scan and experienced mechanic can advise further.

Edited 24 April, 2019 by MicMac

[RobDav99]

Thanks for the reply. 

I'll give the pipes and pump a closer look at the weekend. 

Thanks 

[J.R.]

I think a loss of brake vacuum would trigger the ABS warning light as the system will not function without sufficient vacuum reserve.

[xman]

Did you try pressing the brake pedal really hard when this happened? A loss of vacuum assistance would not stop the brakes from working, but you need to press really very hard on them to make up for loss of assistance. 

 

Otherwise, the symptoms could indicate a problem either in the ABS control system or the ABS hardware. EPS is also controlled via the same hardware. ABS works by intermittently releasing brake circuit pressure for brief (tens of milliseconds) periods. If it were to stick during the cycle you might end with no braking possible at all. The most likely scenario I can think of is contamination in the hydraulic abs control block. When did it last have a brake fluid change?

 

https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-abs-control-module

[RobDav99]

My wife was driving so I didn't feel how it felt myself, she said she tried pumping it and that didnt work and felt like the brakes did nothing at all but she could be mistaken. 

 

Fluid was replaced last year when seized rear caliper was replaced, mot advisory a few weeks ago was that the opposite one is binding slightly now, not sure if that would effect any thing. 

 

I'll check condition of fluid. 

 

I think I've found the lead I bought for my old Audi don't know if its any good for vcds I'll attach pic if anyone can tell from the pcb of it?