DSC & Brake Light Orange - Pressure Sensor Failure

[chazman88]

Hi all,

Been having an issue with the DSC & Brake light coming on orange randomly. Like has been said in a previous thread it seems to happen more in "hotter" weather.
I bought a OBD Cable and got INPA running and below is what I found.

With the "Offset pressure brake circuit 2" still showing a reading, although it is red (error, I'm guessing), could this just be a connectivity error, dry connection, rather than a sensor failure?

If it is a sensor failure, from the research I have done sensor 2 is for the front?

In a couple of weeks I am doing a driving holiday in Scotland and think i really should have the DSC working for driving the Highlands.

Could I change this sensor myself to save myself some money or should I take it to my local independent to get it fixed. If i can do it myself, is there a guide anywhere that could help?

If i need to take it to the indy, anybody got a rough estimate of what it should cost me?

Thanks for the help

Charlie

 

[Adamski]

I had a pulse sensor go on my car - £270ish at main dealer to fix. Indy should of course be cheaper

 

[Mangozac]

Sensor 2 is indeed for the front axle circuit, although note that physically it's the rear sensor on the brake master cylinder.

Since it's intermittent I too would guess at some kind of connection issue. I had pressure sensor issues earlier in the year and after fiddling with the connectors it hasn't been a problem since. Here's my thread on it: http://www.z4-forum.com/forum/viewtopic.php?f=3&t=36590

You can definitely DIY but it does require a small amount of hydraulics if I remember correctly. It's all detailed in the TIS - do you have a copy?

 

[bcworkz]

While limited and incomplete, TIS is available online. It suffices for many things, I use it often since getting to Windows O/S and the real TIS on my computer is a bit of a faff. It does have the info on pressure sensors. Hint: in German, V is for front and H is for rear. Most everything else is in English.

 

[Mangozac]

Yeah I have TIS installed in a Virtual Machine running XP, along with INPA and the other diagnostics stuff.

Hint: in German, V is for front and H is for rear.

But the catch is that the front brake circuit sensor is on the rear of the master cylinder and vice versa 8)

 

[chazman88]

I'm pretty sure I've got TIS on a disc somewhere. Will dig it out and get it installed as I can't see the info I want on the online version.

Cheers

 

[bcworkz]

Yeah I have TIS installed in a Virtual Machine running XP, along with INPA and the other diagnostics stuff.

I was providing general information directed at all readers. I pretty much knew that you would have all the software goodies.
Or did you just seize the opportunity to brag about your computer prowess? oke:

 

[Mangozac]

Or did you just seize the opportunity to brag about your computer prowess? oke:

Let's put it down to bragging for the sake of other forum members

 

[chazman88]

I can't seem to find my copy of TIS and I couldn't find the info I needed on the online version. So maybe somebody would be kind enough to either upload the documents that I need to look at, or give me some "detailed" instructions of where the connectors and sensors are located so I can have a look to make sure they are clean and good.

This week on two different journeys the first half an hour or so the warning lights didn't come on then they just randomly lit up. I wasn't doing anything crazy at the time (I think i was on the motorway) so it really is an random/intermittent fault.

Thanks for all the help guys

Charlie

 

[chazman88]

Ok, so I had a look under the bonnet and found the two sensors attached just under the brake fluid reservoir. I un-plugged them and replugged them to check the connections were ok and as far as I can tell they are as clean as could be. I turned the ignition on and instantly the two warning lights came on. Do I actually need to reset the fault, or if the fault was to "go away" would the lights then not have come on.

As it doesn't appear to be the connection on the sensor itself, is there anything else I could look at before I have to go book it in to get looked at?

Cheers

Charlie

 

[bcworkz]

You need to reset it. The lights are supposed to go away on their own if the fault does not recur after 3 drive cycles. The fault will remain in memory for much longer unless reset. (True for emissions related faults, not too sure about other faults) It's very strange the lights go on & off so frequently.

Here's the TIS page[url] on replacing the #2 brake sensor.

 

[Exactmax]

Was there a successful outcome to this problem as I have the Same issue now

 

[chazman88]

Had the car in at the Indy yesterday. He pointed out that pressure sensor 1 was showing a minus value and pressure sensor 2 was showing a fault. So he changed Both sensors. I drove the car for a little bit last night and the warning didn't come on, but I've had periods longer than that where it hasn't been on. The real test will be when I drive to Scotland on Friday.

The indy mentioned it could have also been a wheel speed sponsor fault or the steering angle sensor. So will need to plug your car into a computer to see what fault codes it has.

Charlir

 

[Mangozac]

Exactmax; there's no catch all cure (especially not without connecting to a computer to find out exactly which sensor is giving problems), however it's definitely worth having a play around with the connectors on the pressure sensors to make sure that the electrical connections are OK.