How hard is it supposed to be?

FoxEye · 5 Jun 2019 at 13:03

So I have long suspected my ABS is not quite doing what it ought to. I've only ever had the one car but have driven Peugeot cars and vans for work (the cars were horrid the vans were quite nice!)

In my little Yaris, when the ABS kicks in the pedal goes limp and sinks all the way to the bottom. There is no resistance at all. There is a "gravel in a blender" noise but not the vibration and stiffness in the pedal I'm lead to believe is the usual tell-tale sign of ABS kicking in.

From what I can Google ABS is a multi-part solution, with all sorts of things like HBB, something called a master cyclinder, a vacuum jobby, various sensors, etc.

All I'm asking is - should the pedal go all the way to the floor, and should I basically have no braking when this happens? Because I have absolutely no braking at all when ABS kicks in. I now basically keep my left hand on the handbrake at all times where I think ABS might come on.

vanpeebles · 5 Jun 2019 at 13:05

You keep the brake held down and the pedal should jiggle.

acemastr · 5 Jun 2019 at 13:21

Time for a mechanic to take a look at it. Definitely should feel vibey and continue braking when it kicks in. It's actually a horrible feeling in a car.

FoxEye · 5 Jun 2019 at 13:23

acemastr said:
Time for a mechanic to take a look at it. Definitely should feel vibey and continue braking when it kicks in. It's actually a horrible feeling in a car.

What I'm most concerned about/ believe is happening is that the ABS is picking up a slow moving wheel and disabling braking on all the wheels. Through some fault.

Because if ABS kicks in at all I'm basically sans brakes. I've already had to ditch the car into a hedge once to avoid a collision... fortunately only cosmetic damage to the wheel rims.

But OTOH the car sails through every MOT since the incident... I'm guessing they do test ABS in an MOT?

e: Google says they don't test ABS; just that the warning lights aren't lit.

FoxEye · 5 Jun 2019 at 13:24

vanpeebles said:
You keep the brake held down and the pedal should jiggle.

It just sinks straight to the floor with no resistance. I don't need to hold it down; it won't spring up again until ABS stops and the gravelly noise goes away.

vanpeebles · 5 Jun 2019 at 13:28

Does it actually slow down though?

Rilot · 5 Jun 2019 at 13:28

Definitely broken. The pedal shouldn't sink to the floor.
When the ABS kicks in the peddle should vibrate but the resistance shouldn't change. I'd say the pump is shot or some valve somewhere.

GeX · 5 Jun 2019 at 13:29

Sounds faulty, and other than making sure there are no lights on they won't afaik test the ABS during MOT - only that the brake components are balanced / effective.
Sounds easy to replicate (slam brakes on) - get it looked at.

FoxEye · 5 Jun 2019 at 13:37

Ta all. Got to see the dealer today for an airbag recall... will ask them about it (but get the work done somewhere with sane prices

)

BUDFORCE · 5 Jun 2019 at 14:34

Woah dude, I'd be very careful about driving the car generally also.

Might be a kid that jumps out in front of you next time rather then a hedge.

But yes, as others have said that definitely ain't right.

sovietspybob · 5 Jun 2019 at 15:05

ABS should feel like someone tapping the back of the brake pedal with a hammer when it's activated, the pedal should still be firm.

Akagi · 5 Jun 2019 at 15:10

I'd remove the ABS fuse until you get it fixed, so that it is safer to drive.

Rroff · 5 Jun 2019 at 15:49

FoxEye said:
the cars were horrid the vans were quite nice!

I have to say I've never rated Peugeot vans - the Mercedes and VWs we have at work seem far better to me.

Scania · 5 Jun 2019 at 16:44

Acme said:
I'd remove the ABS fuse until you get it fixed, so that it is safer to drive.

Nah, just get it fixed, sounds like more than just an abs issue to me.

Doobedoo · 5 Jun 2019 at 16:45

Sounds like an abs sensor or trigger wheel at fault. Had similar issues with my car but it wouldn’t happen all the time but it was quite terrifying when it did, I replaced the offending sensor and it fixed the issue.

FoxEye · 5 Jun 2019 at 19:11

Am booked in a KwikFit tomorrow for a couple new front tyres. They do a free brake check (visual inspection only?) so I'll mention it to them. I spoke to the dealer today but they aren't going to look at it for free and I had some idea of main dealer prices so left it for today.

After all, I'm only willing to pay so much for working brakes

Used to use a local garage but they were useless/incompetent. Never used KwikFit before so fingers crossed they are better than that!

tom_e · 5 Jun 2019 at 19:13

FoxEye said:
Used to use a local garage but they were useless/incompetent. Never used KwikFit before so fingers crossed they are better than that!

Prepare to be amazed...and not in a good way.

Akagi · 5 Jun 2019 at 20:11

Yep...

Clarkey · 5 Jun 2019 at 20:22

ABS fault is beyond the capability of Kwikfit. It's pretty strange that such a fault isn't being detected by the computer, it'll be a pain to diagnose without a DTC.

andy_mk3 · 5 Jun 2019 at 20:26

It's very normal for ABS to cause the pedal to sink. You do not lose any braking, this is just the ABS system modulating the braking pressure.

Source: Mechanic having done 100s of emergency stops in many different cars.

Also though, how hard are you braking to trigger the ABS? I've never triggered it in any of my cars other than in icy conditions under normal driving apart from perhaps one or two very harsh stops to avoid someone.