Audi A8 electronic parking brake ECU - location
Discussion
Yes I did have a full diagnostic done, by an expert who has been right every time so far (except when he asked my daughter to bring her car back in two to three days time, when her Volvo fault had recurred - we were back in less than ten minutes!).
However, he said he thought the handbrake ECU was located under the switch itself (ie in the centre console area) and i really didn't want to start pulling that apart unless i was sure it was.
I already have the boot ECUs out, thanks to having had water under the battery in the autumn. I have replaced the battery control ECU and had that programmed in, and have disconnected and un-programmed the trailer control unit, so will see if I can see the handbrake unit there.
Penny may have just dropped.
My trailer control unit (car has a tow bar) was definitely faulty, and was making the car un-driveable as it thought the car wasn't level so wouldn't start.........and the issue with the handbrake ECU is that the tilt sensor is giving faulty readings. The handbrake works fine (it just passed an MOT), but when you try to engage it it warns you that the car, parked on a level driveway, isn't level enough to use the handbrake.
Could the two things be related in some way? I definitely not only removed the faulty trailer ECU (it was soaking wet) I had the tester tell the car it had no tow bar fitted.
However, he said he thought the handbrake ECU was located under the switch itself (ie in the centre console area) and i really didn't want to start pulling that apart unless i was sure it was.
I already have the boot ECUs out, thanks to having had water under the battery in the autumn. I have replaced the battery control ECU and had that programmed in, and have disconnected and un-programmed the trailer control unit, so will see if I can see the handbrake unit there.
Penny may have just dropped.
My trailer control unit (car has a tow bar) was definitely faulty, and was making the car un-driveable as it thought the car wasn't level so wouldn't start.........and the issue with the handbrake ECU is that the tilt sensor is giving faulty readings. The handbrake works fine (it just passed an MOT), but when you try to engage it it warns you that the car, parked on a level driveway, isn't level enough to use the handbrake.
Could the two things be related in some way? I definitely not only removed the faulty trailer ECU (it was soaking wet) I had the tester tell the car it had no tow bar fitted.
Right - fault cured.
As the space under my battery attracts water, pints of it, I have kept that ECU out of the space underneath. A few weeks ago I put it on top of the battery so that I could put the boot battery access trim back in place, as i wanted a load of luggage in the boot. Of course I should have realised there would be a tilt sensor in the parking brake ECU - common sense, isn't it (to a German after a few too many steins at the Munchener Bierfest, maybe, but not to me), but as I didn't realise the bloody thing had to be horizontal, it wasn't. As soon as it moved to a jaunty angle, the problem began.
I simply placed it flat in the boot again, no more handbrake warning!
Went to fill up with fuel so that i could use the car for 400 miles this coming week, pulled out of the fuel station and a rear light warning came on
Indicators on the dash going at three times the normal speed when I indicated left. Whatever next? Got home, checked all the lights in turn, all present and correct, indicators outside the car at normal speed, on the dashboard going at 250 beats per minute.
I wouldn't mind, but I was planning to sell the car this week!!!
I love this big Audi...but I have had so many problems with it I won't be buying another one, which makes me sad...
As the space under my battery attracts water, pints of it, I have kept that ECU out of the space underneath. A few weeks ago I put it on top of the battery so that I could put the boot battery access trim back in place, as i wanted a load of luggage in the boot. Of course I should have realised there would be a tilt sensor in the parking brake ECU - common sense, isn't it (to a German after a few too many steins at the Munchener Bierfest, maybe, but not to me), but as I didn't realise the bloody thing had to be horizontal, it wasn't. As soon as it moved to a jaunty angle, the problem began.
I simply placed it flat in the boot again, no more handbrake warning!
Went to fill up with fuel so that i could use the car for 400 miles this coming week, pulled out of the fuel station and a rear light warning came on
Indicators on the dash going at three times the normal speed when I indicated left. Whatever next? Got home, checked all the lights in turn, all present and correct, indicators outside the car at normal speed, on the dashboard going at 250 beats per minute.I wouldn't mind, but I was planning to sell the car this week!!!
I love this big Audi...but I have had so many problems with it I won't be buying another one, which makes me sad...
I would suggest you replace it with a similar vintage 7 series or S class.I tend to buy older cars and don't usually have problems. My main motoring is 90 mile journeys on the A1/A14 early in the morning, within the speed limit, cruise control on. 25000 miles a year.
This car had a lot of faults when I test drove it, the dealer spent upwards of £2,000 fixing them and getting it through the MOT. With the benefit of hindsight, it had not been looked after well before I got it, even though the service history was complete (and I did the same).
The automatic gearbox started juddering about 15,000 miles after I got it, at 125,000. It is apparently a well known fault on these cars (D3 A8 2004). It was cured for six months by doing a gearbox oil and filter change, but then it came back. The Audi specialists said it would need a gearbox change. I said no. I have since worked out what the problem is.
These gearboxes are 6-speed, and in D are programmed to drop into 6th gear the moment you reach a steady speed, even as low as 25-30 mph. This only becomes a problem if you are driving in a steady queue of traffic - if you accelerate gently to go with the flow, the gearbox doesn't kick down, which isn't good for it. My normal commute 2 days a week involves 80 miles of 70 mph, but 10 miles at 40ish in a queue, and I use the car for shopping trips too..
After the juddering came back (on gentle acceleration at speeds from 30-60 mph) I discovered that I could reduce the problem by about 85% by using S mode, which keeps the gearbox in third or fourth gear at lower cruising speeds.
The water ingress problem only showed itself last autumn at 160,000 miles, when we had that huge downpour and flooding. I did not drive through deep water, but I suddenly had an array of bizarre faults (car locking and unlocking every five seconds at 60 mph, limp mode, alarm going off and the car refusing to respond to the key, brake lights stuck on for 20 miles at a time). The problems gradually went away, but came back just before Christmas, and the car was off the road or six weeks while they got to the bottom of it. The parking sensors worked, but not reliably, allowing me to back into a low barrier, the aircon compressor failed, and the car just became unrelable.
During the six weeks it was off the road my wife's ML developed a fault where it wouldn't start when hot, and it took over an hour to cool down enough to restart. Turned out to be a faulty crank position sensor after the fourth trip to the diagnostic place. So the only totally reliable vehicle we had was my 15 year old TVR, which never missed a beat and became my daily driver in the middle of winter (at 20 mpg!)
Yes, the Audi is the best car I have ever had in terms of comfort, quality and driving experience ( including 150,000 miles in Lexus LS 400s). Would I have another one? What do you think?
This car had a lot of faults when I test drove it, the dealer spent upwards of £2,000 fixing them and getting it through the MOT. With the benefit of hindsight, it had not been looked after well before I got it, even though the service history was complete (and I did the same).
The automatic gearbox started juddering about 15,000 miles after I got it, at 125,000. It is apparently a well known fault on these cars (D3 A8 2004). It was cured for six months by doing a gearbox oil and filter change, but then it came back. The Audi specialists said it would need a gearbox change. I said no. I have since worked out what the problem is.
These gearboxes are 6-speed, and in D are programmed to drop into 6th gear the moment you reach a steady speed, even as low as 25-30 mph. This only becomes a problem if you are driving in a steady queue of traffic - if you accelerate gently to go with the flow, the gearbox doesn't kick down, which isn't good for it. My normal commute 2 days a week involves 80 miles of 70 mph, but 10 miles at 40ish in a queue, and I use the car for shopping trips too..
After the juddering came back (on gentle acceleration at speeds from 30-60 mph) I discovered that I could reduce the problem by about 85% by using S mode, which keeps the gearbox in third or fourth gear at lower cruising speeds.
The water ingress problem only showed itself last autumn at 160,000 miles, when we had that huge downpour and flooding. I did not drive through deep water, but I suddenly had an array of bizarre faults (car locking and unlocking every five seconds at 60 mph, limp mode, alarm going off and the car refusing to respond to the key, brake lights stuck on for 20 miles at a time). The problems gradually went away, but came back just before Christmas, and the car was off the road or six weeks while they got to the bottom of it. The parking sensors worked, but not reliably, allowing me to back into a low barrier, the aircon compressor failed, and the car just became unrelable.
During the six weeks it was off the road my wife's ML developed a fault where it wouldn't start when hot, and it took over an hour to cool down enough to restart. Turned out to be a faulty crank position sensor after the fourth trip to the diagnostic place. So the only totally reliable vehicle we had was my 15 year old TVR, which never missed a beat and became my daily driver in the middle of winter (at 20 mpg!)
Yes, the Audi is the best car I have ever had in terms of comfort, quality and driving experience ( including 150,000 miles in Lexus LS 400s). Would I have another one? What do you think?
Not in the same class, but I have just spent £1500 on an 8 year old, 120,000 mile Saab 9-5 as a replacement. The Audi at similar mileage was £7300 in 2012. The Saab is even more comfortable than the Audi. I have had two before, always reliable. We'll see how it goes, but my depreciation should be fairly low 
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