Electrical issue on my C6 generation A6
Discussion
I’ve got a bit of a problem with my 2005 C6 generation Audi A6, so I thought I’d post up on here to see if anyone might have experienced something similar with another VAG car.
After more than 40 minutes of driving, the car beeps and the DSC warning light and what I think is a yellow brake warning light appears on the integrated dash display. These then immediately disappear, but the DSC light on the dash itself remains illuminated. The instant this happens, the car exhibits what feels like a serious gearbox fault - the car revs freely but barely moves, it becomes difficult to change gear even with the paddles. Turning the car on and off again has no effect, leaving it to cool down for an hour totally resolves the problem, with all lights no longer illuminated on the dash.
This issue has kind of occurred before in the sense that once or twice, during a long drive, the DSC dash light would illuminate and I would feel a hesitation or shudder in the gearbox. However, after a couple of seconds, it would sort itself out, although the DSC light would stay illuminated. At the time, I put it down to a sensor issue but this recent development where I had to crawl to the next junction at 30MPH would indicate that it’s something more serious.
After researching online, I noticed a couple of people with similar problems reported changing the brake pedal switch solved the issue for them. I put the car into the dealer and mentioned this, but they called me this evening stating that they didn’t think it was anything to do with the switch as it “wasn’t showing a fault code” (personally I was surprised that their diagnostics are that precise, but I know little about such things).
They then admitted that they’re pretty sure there’s nothing wrong with the gearbox either, and that it’s likely to be some sort of connection / wiring issue, which will involve taking the entire car apart to sort out. Understandably, I’m reluctant to let them do this as I’ve already spent over half the value of the car in repairs in the month or so I’ve had it.
Do we think it’s worth changing the brake pedal switch myself to see if it fixes it, considering it’s a cheap part. Is there anything else I should be checking?
After more than 40 minutes of driving, the car beeps and the DSC warning light and what I think is a yellow brake warning light appears on the integrated dash display. These then immediately disappear, but the DSC light on the dash itself remains illuminated. The instant this happens, the car exhibits what feels like a serious gearbox fault - the car revs freely but barely moves, it becomes difficult to change gear even with the paddles. Turning the car on and off again has no effect, leaving it to cool down for an hour totally resolves the problem, with all lights no longer illuminated on the dash.
This issue has kind of occurred before in the sense that once or twice, during a long drive, the DSC dash light would illuminate and I would feel a hesitation or shudder in the gearbox. However, after a couple of seconds, it would sort itself out, although the DSC light would stay illuminated. At the time, I put it down to a sensor issue but this recent development where I had to crawl to the next junction at 30MPH would indicate that it’s something more serious.
After researching online, I noticed a couple of people with similar problems reported changing the brake pedal switch solved the issue for them. I put the car into the dealer and mentioned this, but they called me this evening stating that they didn’t think it was anything to do with the switch as it “wasn’t showing a fault code” (personally I was surprised that their diagnostics are that precise, but I know little about such things).
They then admitted that they’re pretty sure there’s nothing wrong with the gearbox either, and that it’s likely to be some sort of connection / wiring issue, which will involve taking the entire car apart to sort out. Understandably, I’m reluctant to let them do this as I’ve already spent over half the value of the car in repairs in the month or so I’ve had it.
Do we think it’s worth changing the brake pedal switch myself to see if it fixes it, considering it’s a cheap part. Is there anything else I should be checking?
Dr G said:
Which engine/box? If multitronic that sounds like the old school multitronic clutch pack failure.
Brake pedal switches didn't used to throw fault codes (you'd suddenly lose cruise/brake lights or even get weirdness with ESP). Not sure if they do now.
It is indeed multitronic, with the 3.0 V6 petrol. My first thought was clutch pack failure too, but then as far as I’m aware that wouldn’t throw up those warning lights on the dash?Brake pedal switches didn't used to throw fault codes (you'd suddenly lose cruise/brake lights or even get weirdness with ESP). Not sure if they do now.
When the ECU sees something it deems as implausible it can throw some very odd codes. ECU sees engine doing X and gearbox doing X which should equal a road speed of Y. When that speed is Z instead things start to get confused.
A fault code/warning don't necessarily tell you what's wrong, they only tell you what the ECU can see given the information available.
A fault code/warning don't necessarily tell you what's wrong, they only tell you what the ECU can see given the information available.
Dr G said:
When the ECU sees something it deems as implausible it can throw some very odd codes. ECU sees engine doing X and gearbox doing X which should equal a road speed of Y. When that speed is Z instead things start to get confused.
A fault code/warning don't necessarily tell you what's wrong, they only tell you what the ECU can see given the information available.
Interesting, thanks. If it is indeed the clutch pack, I'm inclined to get rid.A fault code/warning don't necessarily tell you what's wrong, they only tell you what the ECU can see given the information available.
So, I’ve been driving it around whilst waiting for the new switch to arrive, and have been monitoring the issue.
Tonight, it did the following:
Performed totally normally for around 30 minutes. Then ESP light comes on, car comes out of gear, then sorts itself out. A couple more slight hiccups in the next 10 minutes, but nothing major.
Then, the yellow handbrake malfunction light in the dash screen comes on for a second, and the car comes out of gear again. This only lasts for a second or 2, then the light goes off and the car is fine. Throughout the next 30 minutes this happened every 3-5 minutes, with the car briefly coming out of gear each time the handbrake malfunction light came on, then coming back into gear when the light went off after a couple of seconds.
Dr G - do you think this confirms your theory?
Tonight, it did the following:
Performed totally normally for around 30 minutes. Then ESP light comes on, car comes out of gear, then sorts itself out. A couple more slight hiccups in the next 10 minutes, but nothing major.
Then, the yellow handbrake malfunction light in the dash screen comes on for a second, and the car comes out of gear again. This only lasts for a second or 2, then the light goes off and the car is fine. Throughout the next 30 minutes this happened every 3-5 minutes, with the car briefly coming out of gear each time the handbrake malfunction light came on, then coming back into gear when the light went off after a couple of seconds.
Dr G - do you think this confirms your theory?
So, I finally bought VCDS and got it hooked up. In the last few weeks it's mostly been behaving itself - the parking brake fault light is now permanently illuminated and will not disappear even when the code is cleared in VCDS, but apart from the occasional cutting out for a second or two the car has been OK.
A couple of days ago, it cut out again, the red battery warning light came on the dash and the power steering stopped functioning. I coasted to a parking space, turned the car on and off again and it was fine. The battery is new.
I read the codes today, there were a vast number for all kinds of different things - mostly old stuff that I don't think has anything to do with my problem. These are the ones that I think are the most pertinent:
01315 - Gearbox control unit
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 2
Error frequency: 7
Distributor counter: 111
Mileage: 108988 km
Time specification: 0
Date: 2018.01.29
Time: 18:49:52
00473 - Control unit for electric parking brake/hand brake (J540)
008 - implausible signal
Ambient conditions:
Error status: 01101000
Error priority: 3
Error frequency: 1
Distributor counter: 75
Mileage: 109258 km
Time specification: 0
Date: 2018.02.07
Time: 15:09:47
00263 - Gearbox
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 2
Error frequency: 35
Distributor counter: 98
Mileage: 108894 km
Time specification: 0
Date: 2018.01.24
Time: 19:18:10
01315 - Gearbox control unit
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 2
Frequency of errors: 36
Distributor counter: 98
Mileage: 108894 km
Time specification: 0
Date: 2018.01.24
Time: 19:18:11
01312 - Data bus drive
014 - defective - sporadic
Ambient conditions:
Error status: 00101110
Error priority: 1
Error frequency: 14
Distributor counter: 111
Mileage: 108959 km
Time specification: 0
Date: 2018.01.25
Time: 19:39:19
00384 - Optical data bus
011 - Interruption - Sporadic
Ambient conditions:
Error status: 00101011
Error priority: 5
Error frequency: 1
Distributor counter: 112
Mileage: 109851 km
Time specification: 0
Date: 2018.02.20
Time: 17:11:32
01314 - Engine control unit
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 3
Error frequency: 119
Distributor counter: 113
Mileage: 108959 km
Time specification: 0
Date: 2018.01.25
Time: 19:39:25
01316 - Brake control unit
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 3
Error frequency: 17
Distributor counter: 86
Mileage: 108961 km
Time specification: 0
Date: 2018.01.25
Time: 19:41:54
02432 - Parking motor left Power supply (V282)
011 - Interruption - Warning light ON
Ambient conditions:
Error status: 11101011
Error priority: 2
Error frequency: 79
Distributor counter: 56
Mileage: 109256 km
Time specification: 0
Date: 2018.02.07
Time: 15:09:45
Ambient conditions:
Voltage: 11.80 V
Quantity: 116
In my limited knowledge, this points to a fault with the gearbox ECU which is then causing other faults in other modules such as the ESP and parking brake module. However, when I tried to clear the parking brake fault in VCDS, the car beeped at me and several lights flashed up on the dash, including the ESP, ABS and red park brake indicator. The other thing which makes me doubt this slightly is the fault I had a couple of days ago with the battery light and power steering, which to me would suggest an alternator issue. This is the only time it's happened however, and it could be totally unrelated.
So, any ideas? I suspect I may be asking a bit much here as this seems to be fairly specialist stuff. I certainly can't find anyone here (including the Audi dealer) who seems to be able to give me a reliable diagnosis.
A couple of days ago, it cut out again, the red battery warning light came on the dash and the power steering stopped functioning. I coasted to a parking space, turned the car on and off again and it was fine. The battery is new.
I read the codes today, there were a vast number for all kinds of different things - mostly old stuff that I don't think has anything to do with my problem. These are the ones that I think are the most pertinent:
01315 - Gearbox control unit
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 2
Error frequency: 7
Distributor counter: 111
Mileage: 108988 km
Time specification: 0
Date: 2018.01.29
Time: 18:49:52
00473 - Control unit for electric parking brake/hand brake (J540)
008 - implausible signal
Ambient conditions:
Error status: 01101000
Error priority: 3
Error frequency: 1
Distributor counter: 75
Mileage: 109258 km
Time specification: 0
Date: 2018.02.07
Time: 15:09:47
00263 - Gearbox
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 2
Error frequency: 35
Distributor counter: 98
Mileage: 108894 km
Time specification: 0
Date: 2018.01.24
Time: 19:18:10
01315 - Gearbox control unit
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 2
Frequency of errors: 36
Distributor counter: 98
Mileage: 108894 km
Time specification: 0
Date: 2018.01.24
Time: 19:18:11
01312 - Data bus drive
014 - defective - sporadic
Ambient conditions:
Error status: 00101110
Error priority: 1
Error frequency: 14
Distributor counter: 111
Mileage: 108959 km
Time specification: 0
Date: 2018.01.25
Time: 19:39:19
00384 - Optical data bus
011 - Interruption - Sporadic
Ambient conditions:
Error status: 00101011
Error priority: 5
Error frequency: 1
Distributor counter: 112
Mileage: 109851 km
Time specification: 0
Date: 2018.02.20
Time: 17:11:32
01314 - Engine control unit
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 3
Error frequency: 119
Distributor counter: 113
Mileage: 108959 km
Time specification: 0
Date: 2018.01.25
Time: 19:39:25
01316 - Brake control unit
004 - no signal/communication - sporadic
Ambient conditions:
Error status: 00100100
Error priority: 3
Error frequency: 17
Distributor counter: 86
Mileage: 108961 km
Time specification: 0
Date: 2018.01.25
Time: 19:41:54
02432 - Parking motor left Power supply (V282)
011 - Interruption - Warning light ON
Ambient conditions:
Error status: 11101011
Error priority: 2
Error frequency: 79
Distributor counter: 56
Mileage: 109256 km
Time specification: 0
Date: 2018.02.07
Time: 15:09:45
Ambient conditions:
Voltage: 11.80 V
Quantity: 116
In my limited knowledge, this points to a fault with the gearbox ECU which is then causing other faults in other modules such as the ESP and parking brake module. However, when I tried to clear the parking brake fault in VCDS, the car beeped at me and several lights flashed up on the dash, including the ESP, ABS and red park brake indicator. The other thing which makes me doubt this slightly is the fault I had a couple of days ago with the battery light and power steering, which to me would suggest an alternator issue. This is the only time it's happened however, and it could be totally unrelated.
So, any ideas? I suspect I may be asking a bit much here as this seems to be fairly specialist stuff. I certainly can't find anyone here (including the Audi dealer) who seems to be able to give me a reliable diagnosis.
Geekman said:
The battery is new.
Was the battery controller properly recoded when the battery was replaced?http://wiki.ross-tech.com/wiki/index.php/Battery_R...
eta,
This is a very similar-sounding circumstance. Like you , the handbrake caliper voltage shows low, http://forums.ross-tech.com/showthread.php?3249-El...
If you've bought a legit VCDS set up and not a hooky Chinese one, register there and you'll get some very good detailed help with interpreting the codes you are seeing.
Edited by shtu on Thursday 22 February 11:30
Yes, the battery was coded when installed. Having had a look at the link for the other guy's problem, I'm pretty sure it's not the same as mine as he doesn't seem to have anywhere near the same amount of error codes in different modules which I have.
I live in Mexico, so my VCDS isn't genuine as I bought it locally. I've had endless problems getting stuffed shipped from the US and UK to here, with customs holding stuff for ages, trying to charge me, etc etc so I didn't want to risk ordering it from the US. Likewise, finding an auto electrician with experience of these cars is near enough impossible.
If I still have the car next time I head up to the US, I'll try to get my hands on a genuine VCDS system.
I live in Mexico, so my VCDS isn't genuine as I bought it locally. I've had endless problems getting stuffed shipped from the US and UK to here, with customs holding stuff for ages, trying to charge me, etc etc so I didn't want to risk ordering it from the US. Likewise, finding an auto electrician with experience of these cars is near enough impossible.
If I still have the car next time I head up to the US, I'll try to get my hands on a genuine VCDS system.
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