Facelift A3 Brakes Locking Up

[The Kendragon]

Hi all,

My A3 Sportback has been locking up at times since I got it in March. It used to happen when I was at higher speeds and braking sharply so I expected it and I’d say it was normal.

More recently though, at lower speeds 20-30mph when braking with a bit of force, all four wheels lock up and the car slides. There’s no traction control lights on the dash and there’s no real way of controlling the skid.

This morning I was going at 20mph around a corner and there was a lorry on the other side. I braked (nothing major but wanting to stop) and the car just kept going and all four wheels locked up. The result was nearly sliding into the lorry.

Has anyone else had this? Not sure if it’s linked to the handbrake issues I’ve been having.

Thanks,

Steven

 

[davemk]

Surely that's a fault? ABS should prevent locking up, shouldn't it??

 

[GW1]

It sounds like you have an ABS issue; there must be a fault showing on the DIS. I would definitely not be driving your car until the fault is rectified.

 

[The Kendragon]

Surely that's a fault? ABS should prevent locking up, shouldn't it??

That’s what I’m thinking but I’m not 100% sure. It’s scary when it slides because you feel a total loss of control and there’s no traction control light saying that the car is trying to regain control.... It has been into Audi very few weeks for about three months now!

It sounds like you have an ABS issue; there must be a fault showing on the DIS. I would definitely not be driving your car until the fault is rectified.

Nothing shows on the DIS and I don’t even get the flashing yellow traction control warning when I’m sliding along.... The weirdest thing is that it’ll do it at 20mph! I expect my Audi to be able to stop controllably at that speed

 

[davemk]

I think I'd be asking for it to be recovered, rather than driving it to the dealers. Something definitely seems amiss to me.

 

[suzannec]

I think Audi need to see it again.
Can you get a VCDS scan as there must be some fault codes triggering when that happens.
#scary

 

[KenL]

You should feel a pulsing in the brake pedal and some horrible noises when ABS kicks in.

 

[cemerson]

Get it checked.

But also, braking on a corner is not the best idea...

 

[Retroman]

Very strange and unusual fault. ABS doesn't usually work at very low speeds (not sure what the Audi cut-off is) but generally its in the 10 - 20 MPH. As said already, ABS pulsates to avoid skidding and if something causes it to receive an implausible signal it normally switches itself off showing instrument panel warning lights etc. Are you sure that all four wheels are locking or just the rear handbrake mechanism - the handbrake mechanism (I assume electric) is what I would suspect. However, as said already the car does not sound safe in its current format and should be returned to Audi.

 

[The Kendragon]

***I said very in an earlier post and I meant every***

I think I'd be asking for it to be recovered, rather than driving it to the dealers. Something definitely seems amiss to me.

Seems that way to me too so I’ll definitely call Audi tomorrow and see what’s what... This will be the third time it’s gone in for braking issues!

I think Audi need to see it again.
Can you get a VCDS scan as there must be some fault codes triggering when that happens.
#scary

Agreed but unfortunately I don’t have any way of seeing the fault codes as I’ve not got a VCDS machine

You should feel a pulsing in the brake pedal and some horrible noises when ABS kicks in.

I don’t get that, it just starts to brake and then slides along until it stops.....

Get it checked.

But also, braking on a corner is not the best idea...

I was only braking on the corner due to the lorry blocking the road when I came round. It’s a blind bend so that’s why I was going 20mph rather than the 60mph speed limit. Didn’t expect to nearly hit it by sliding along though!

Very strange and unusual fault. ABS doesn't usually work at very low speeds (not sure what the Audi cut-off is) but generally its in the 10 - 20 MPH. As said already, ABS pulsates to avoid skidding and if something causes it to receive an implausible signal it normally switches itself off showing instrument panel warning lights etc. Are you sure that all four wheels are locking or just the rear handbrake mechanism - the handbrake mechanism (I assume electric) is what I would suspect. However, as said already the car does not sound safe in its current format and should be returned to Audi.

Interesting that it has a cut off point but my car definitely doesn’t pulsate when braking. It just slides if it’s anything more than moderate braking with no warning lights. The front wheels definitely lock and due to the car sliding I’m assuming the back ones are locking up too :/ I’ll be calling Audi tomorrow to explain that this issue has got worse since the handbrake has been playing up. Nightmare!

 

[AudiNutta]

Damn you don't have much luck!

 

[mikemod]

It does sound as if it is related to your handbrake issue.

If you apply the handbrake when you are driving it does an emergency stop and will lock all four wheels as you are describing.

 

[GW1]

It does sound as if it is related to your handbrake issue.

If you apply the handbrake when you are driving it does an emergency stop and will lock all four wheels as you are describing.

Are you sure I thought the electromechanical hand brake only acted on the rear wheels.

 

[richinsoton]

Are you sure I thought the electromechanical hand brake only acted on the rear wheels.

It's mentioned in the manual -

You can use the emergency braking function in emergencies or if the main brake system fails or the pedal is obstructed.
Pull and hold the button

.
The brakes will be released immediately if you release the button

or press the accelerator.
If you pull and hold the button

while the vehicle is moving, this will initiate an emergency brake application. The brakes are then applied hydraulically at all four wheels. The effect is similar to heavy braking ►.
To prevent the emergency braking function from being used accidentally, a warning buzzer sounds when the button

is operated. The brakes are released immediately when you release the button

or press the accelerator.

 

[GW1]

It's mentioned in the manual -

You can use the emergency braking function in emergencies or if the main brake system fails or the pedal is obstructed.
Pull and hold the button

.
The brakes will be released immediately if you release the button

or press the accelerator.
If you pull and hold the button

while the vehicle is moving, this will initiate an emergency brake application. The brakes are then applied hydraulically at all four wheels. The effect is similar to heavy braking ►.
To prevent the emergency braking function from being used accidentally, a warning buzzer sounds when the button

is operated. The brakes are released immediately when you release the button

or press the accelerator.

I watched a video on YouTube where a guy was changing the rear pads on an S3. He didn’t use VCDS but removed an electric motor from one of the rear brake mountings and I thought that was what the electromechanical brake acted on, ie just the rear brakes. That said I bow to your superior knowledge on this matter and I must start reading the instruction manual 432 pages. Haha

 

[AJB]

I watched a video on YouTube where a guy was changing the rear pads on an S3. He didn’t use VCDS but removed an electric motor from one of the rear brake mountings and I thought that was what the electromechanical brake acted on, ie just the rear brakes. That said I bow to your superior knowledge on this matter and I must start reading the instruction manual 432 pages. Haha

The electro mechanical parking brake which you put on, or which comes on, when you park is operated by those motors and just on the rear brakes.

However, if you pull the handbrake switch whilst on the move in an emergency it used the "normal" hydraulic brakes on all 4 wheels, with abs.

I'm assuming that if that doesn't work (e.g. complete hydraulic failure on both circuits) it might use the parking brake, but that's just a guess.

 

[The Kendragon]

Damn you don't have much luck!

I know right, ****** car!

It does sound as if it is related to your handbrake issue.

If you apply the handbrake when you are driving it does an emergency stop and will lock all four wheels as you are describing.

Hmmm interesting! It’s not random though, it is only when I’m braking quite hard anyway. Just don’t expect the car to slide and I don’t expect it not to show the flashing ESP light :/ When I’ve turned at junctions and the road surface is loose, the light comes on so it’s weird it doesn’t when the car is sliding and clearly has no grip. Does seem intermittent though because I could only replicate it every now and then yesterday down an empty road

 

[AJB]

It’s not random though, it is only when I’m braking quite hard anyway. Just don’t expect the car to slide and I don’t expect it not to show the flashing ESP light :/

The ESP light only flashes when traction control and/or stability control are activated. ABS activation doesn't light the ESP light as far as I'm aware.

(Traction control is the car lifting off the power and/or applying individual brakes to reduce wheelspin, stability control is the car lifting off the power and/or applying individual brakes to correct oversteer/understeer. ABS is the car pulsing the brakes you're applying on/off rapidly to keep a wheel turning that'd lock up otherwise, meaning that you've still got steering control via a rotating road wheel).

ABS activation is felt through the brake pedal as a kind of fast graunching/vibrating sensation as it removes and reapplies the brake pressure you've built up underneath your foot.

 

[The Kendragon]

The ESP light only flashes when traction control and/or stability control are activated. ABS activation doesn't light the ESP light as far as I'm aware.

(Traction control is the car lifting off the power and/or applying individual brakes to reduce wheelspin, stability control is the car lifting off the power and/or applying individual brakes to correct oversteer/understeer. ABS is the car pulsing the brakes you're applying on/off rapidly to keep a wheel turning that'd lock up otherwise, meaning that you've still got steering control via a rotating road wheel).

ABS activation is felt through the brake pedal as a kind of fast graunching/vibrating sensation as it removes and reapplies the brake pressure you've built up underneath your foot.

Thank you so much for the explanation In that case, I get no unusual feelings through the brake pedal and when I steer nothing happens because no wheels are moving. When it happens I’m just a sitting duck while my Audi slides in the direction it was facing. Like I say it’s only happened at 20-30mph so far so nothing too dangerous. Will get it looked at though!

EDIT: Car has been booked in for Tuesday. Hopefully they confirm the issue or can at least fix it