Almost got killed: brakes and air condition not working when on cruise control

[dpalinic]

Hi everyone,

I have a strange, and dangerous problem with my Audi A3 Sportback, 8V, 1.4 TFSI (March 2013) and I was unable to find any other similar problem on the forum or the internet.

Very often, when I activate a cruise control (faster then 130 Km/h), after some period of time, like 1-2 minutes, brakes just stop working as brake pedal starts to be hard/stiff as a rock. At the same time, air condition stops working (air is not cold anymore - just blows the air from the outside). Not sure what is a connection between these two problems...

These are the ways how to bring the brakes and air condition back to normal when this happens:
- If I deaccelerate below ~130 Km/h by decreasing the cruise control speed, brake pedal and air condition are back to normal.
- If I hit the brake pedal like a maniac, after ~2 seconds, brakes starts to be soft again, brakes start to work and air condition starts to blow cold air
- If I deactivate the cruise control with the cancel button, brakes starts to be soft again, brakes start to work and air condition starts to blow cold air

I don't need to say that I'm not using the cruise control anymore, as this is a very dangerous problem... I almost crushed with a truck on the highway when this happened for the first time as truck entered my lane and I couldnt brake. I was not expecting this kind of problem with a car, especially with an Audi.

Did anyone hear of a similar problem? My car was checked by the official Audi service, but no error codes where found, and they don't know why is this happening yet.

Thanks,
Damir

 

[andywil13]

Have they kept the car in the meantime?

 

[dpalinic]

Nope... We agreed that we'll go and test it together on the highway in 10 days when some guy from the service comes back to work. They need to reproduce the issue first, and then ask the factory about the problem...

 

[cemerson]

10 days? So they've given you back a dangerous car and said to keep using it for 10 days? Unbelievable!

 

[dpalinic]

It's probably my mistake as I haven't insisted for them to keep it... The car behaves ok when it's not on cruise control... but, you're right, that doesn't mean that it won't stop working without cruise control as well

 

[The Challinor]

Yer not sure if I'd have wanted to drive the car away in that state, sounds really bad.

 

[steeve]

Sadly things like this only get worse, I do hope that's not the case with your car. Please be careful.

 

[dpalinic]

Sadly things like this only get worse, I do hope that's not the case with your car. Please be careful.

Yeah, I don't have much luck with electronic devices anyway (computer freezes, mobile phone has bugs, my car also...) I hope that they will be able to find the problem... if not, my only chance is to ask for a new car but they will say big NO to that proposal.

 

[cemerson]

Yeah, I don't have much luck with electronic devices anyway (computer freezes, mobile phone has bugs, my car also...) I hope that they will be able to find the problem... if not, my only chance is to ask for a new car but they will say big NO to that proposal.

Pretty sure EU law would let you reject the car after giving them a certain number of tries to fix it... or is that just in the UK? I heard the EU were doing something similar.

 

[veeeight]

This government is introducing a new UK Consumer Rights Act (currently a Bill, making its way through Parliament) will:

Let people who place an order for their car online have a 14 day cooling off period
Get a refund within 14 days of cancellation
Allow owners to reject a car within 30 days should it suffer a fault
Allow owners to reject a car within 6 months after ONE attempt at a failed repair


The Act will be law later this year, once it has passed through Parliament (both Houses), and Royal Ascent.

The Consumer Rights Bill | Improving Consumer Law

Consumer Rights Bill 2013-14 to 2014-15 — UK Parliament

 

[cilurnum]

Whatever this is you have to get them to reproduce it, and hopefully when it is reproduced nothing else bad will happen.

The air con thing sounds like something weird is happening over the canbus or something, and that is NOT good.

 

[Longy]

So can you reproduce that issue over again? So every time you set it at 130 km or over does the same thing happen.

If its at those speeds, we would never be able to test that here in Australia, as 110km/hr is normally the fastest speed you can do here apart from some stretch of roads in the desert.

 

[voorhees]

I am surprised at them giving you the car back but I suppose as long as you stay south of 130 kmh (81mph) you are safe...ish.

 

[bobinder]

I'm surprised they haven't offered to test it on a track, are they expecting you to reproduce this fault on the public highways?

 

[cuke2u]

From what the OP is describing it does sound similar to a stopped engine, although usually the steering goes very stiff as well. EPAS systems might be different though..

 

[mjcourtney]

The cruise control on the 8V actually takes over the brake control as well as the throttle. This is to help maintain speed whilst going down a hill as it lightly applies the brakes.

It sounds like this capture / release of the brake control isn't being handled correctly by the Cruise Control system. When it's operating normally you'll find that the brakes are very sensitive when going downhill on CC, as they have already been pre-applied to reduce speed. If anything this makes braking too easy, as the force required to brake is a lot less than you're expecting.

The fact that you're also experiencing issues with other systems (Air Con) does suggest this is an electrical / CANBUS fault.

 

[dpalinic]

So can you reproduce that issue over again? So every time you set it at 130 km or over does the same thing happen.

If its at those speeds, we would never be able to test that here in Australia, as 110km/hr is normally the fastest speed you can do here apart from some stretch of roads in the desert.

Yes, usually I can reproduce the issue without a problem, but sometimes it just work as expected. For example, I went to a highway few days ago to test this, and for 60 kilometers everything worked just fine. When i was driving back, after few hours, I could reproduce it every single time. Really strange...

 

[dpalinic]

I'm surprised they haven't offered to test it on a track, are they expecting you to reproduce this fault on the public highways?

Unfortunatelly, there is no track near my city... The highway is the only way to reproduce it without taking a car somewhere where the track is (I don't even know where the good one is near Split, Croatia), but we need to be very very careful while doing that.

 

[nothingness]

Allow owners to reject a car within 6 months after ONE attempt at a failed repair

I can see that getting abused!

 

[dpalinic]

From what the OP is describing it does sound similar to a stopped engine, although usually the steering goes very stiff as well. EPAS systems might be different though..

All other things besides brakes and air condition are working as usual... Steering wheel stiffnes is normal when that happen, although while driving at that speed, I guess that there will be no difference in the stiffnes between a car having and not havnig a hydraulic steering wheel so I'm not sure if I can test that easily. Any suggestion how to inspect that?

 

[dpalinic]

The cruise control on the 8V actually takes over the brake control as well as the throttle. This is to help maintain speed whilst going down a hill as it lightly applies the brakes.

It sounds like this capture / release of the brake control isn't being handled correctly by the Cruise Control system. When it's operating normally you'll find that the brakes are very sensitive when going downhill on CC, as they have already been pre-applied to reduce speed. If anything this makes braking too easy, as the force required to brake is a lot less than you're expecting.

The fact that you're also experiencing issues with other systems (Air Con) does suggest this is an electrical / CANBUS fault.

I have noticed that when car is going uphill, this fault is much easier to reproduce... Not sure if that is connected with what you explained above, but it could be. If the CANBUS is a problem, is that a very hard/complicated thing for a dealer to replace?

 

[cuke2u]

All other things besides brakes and air condition are working as usual... Steering wheel stiffnes is normal when that happen, although while driving at that speed, I guess that there will be no difference in the stiffnes between a car having and not havnig a hydraulic steering wheel so I'm not sure if I can test that easily. Any suggestion how to inspect that?

As I understand it the 8v has electrically assisted steering and doesn't possess any hydraulic assistance.

 

[steeve]

As I understand it the 8v has electrically assisted steering and doesn't possess any hydraulic assistance.

True