Transmission Woes - My turn
08-21-2013, 10:51 PM
#11
AudiWorld Member
limp mode
Here's my take on what has happened.
If there was a loud thump and jolt when this happened, this tells me that it's not from the torque converter clutch disengaging. If it disengages, it's just going to allow a smooth increase of RPM, and not create a jolt. Also, the increase in RPM you talk about seems too much for just the TCC unlocking.
I think the transmission has momentarily gone into limp mode, which just shoves it into 4th gear. The transmission normally uses electronics to control the solenoids that change gears. Because of the electronics involved, this makes the changes nice and smooth. If this system fails, there is the manual valve on the side of the valve body that can put the transmission into either P, R, or 4th, depending on the gear lever position. It bypasses all of the electronics and most of the valve body, and for this reason the change is very abrupt. In this case because you were probably in D, it has just shoved it into 4th, and due to the abrupt nature of the change, it feels like you've hit something. I've had our transmission go into limp mode before, and just selecting R or D from a standstill feels like you've been hit from behind.
Why has it gone into limp mode? Could be any number of reasons, but the first things to do are what you are doing. Change the fluid (don't just check the level and top up), but most importantly get a copy of VAG-COM and read the codes. They will tell you what is going on. If the fluid level is correct, it's most likely an intermittent electrical fault. Only the error codes will tell you this.
Prior to fixing the problem, my advice is to not drive the car too fast, as it dropping into 4th quickly is going to put a lot of strain on the drivetrain. It makes sense to me that when it happened to your wife at slower speed, the feeling inside the car was less abrupt.
The problem on our car was the gear selection switch that sits on the outside of the transmission. Massive job to change, and expensive due to the price charged by Audi for the switch, and where it is located on the left side behind the transmission mount. I hypothesised it was just some corrosion on the contacts inside the switch, so I just put the key in position 2 (engine not going), and moved the gear lever back and forth from P to Sport about 100 times to try and clean up the contacts. 2 years later it hasn't happened again.
I also had a similar problem on my BMW, which also has the ZF 5HP19 transmission (RWD version). In this case it was just the contacts on the plug that comes from the switch. I cleaned these up and the problem has never repeated itself.
If the codes tell you this is the problem, taking it to a dealership will just result in them telling you it needs replacing, with the associated huge bill (here in Australia it was going to cost about $1500). My experience tells me this isn't normally required.
I've pulled apart one of these transmissions, including the plug. The plug design makes them not prone to fail internally, so it's normally a electrical contact problem. If you want to have a look at the switch and what it does, have a look at the link below.
http://forum.e46fanatics.com/showthr...0#post14551400
As an aside, I don't think the Audi transmissions have the same reverse fail problems that other ZF 5HP19 transmissions have. The reverse drum that fails is a different design on the Audi transmissions, which is most likely a result of failures on other cars.
If there was a loud thump and jolt when this happened, this tells me that it's not from the torque converter clutch disengaging. If it disengages, it's just going to allow a smooth increase of RPM, and not create a jolt. Also, the increase in RPM you talk about seems too much for just the TCC unlocking.
I think the transmission has momentarily gone into limp mode, which just shoves it into 4th gear. The transmission normally uses electronics to control the solenoids that change gears. Because of the electronics involved, this makes the changes nice and smooth. If this system fails, there is the manual valve on the side of the valve body that can put the transmission into either P, R, or 4th, depending on the gear lever position. It bypasses all of the electronics and most of the valve body, and for this reason the change is very abrupt. In this case because you were probably in D, it has just shoved it into 4th, and due to the abrupt nature of the change, it feels like you've hit something. I've had our transmission go into limp mode before, and just selecting R or D from a standstill feels like you've been hit from behind.
Why has it gone into limp mode? Could be any number of reasons, but the first things to do are what you are doing. Change the fluid (don't just check the level and top up), but most importantly get a copy of VAG-COM and read the codes. They will tell you what is going on. If the fluid level is correct, it's most likely an intermittent electrical fault. Only the error codes will tell you this.
Prior to fixing the problem, my advice is to not drive the car too fast, as it dropping into 4th quickly is going to put a lot of strain on the drivetrain. It makes sense to me that when it happened to your wife at slower speed, the feeling inside the car was less abrupt.
The problem on our car was the gear selection switch that sits on the outside of the transmission. Massive job to change, and expensive due to the price charged by Audi for the switch, and where it is located on the left side behind the transmission mount. I hypothesised it was just some corrosion on the contacts inside the switch, so I just put the key in position 2 (engine not going), and moved the gear lever back and forth from P to Sport about 100 times to try and clean up the contacts. 2 years later it hasn't happened again.
I also had a similar problem on my BMW, which also has the ZF 5HP19 transmission (RWD version). In this case it was just the contacts on the plug that comes from the switch. I cleaned these up and the problem has never repeated itself.
If the codes tell you this is the problem, taking it to a dealership will just result in them telling you it needs replacing, with the associated huge bill (here in Australia it was going to cost about $1500). My experience tells me this isn't normally required.
I've pulled apart one of these transmissions, including the plug. The plug design makes them not prone to fail internally, so it's normally a electrical contact problem. If you want to have a look at the switch and what it does, have a look at the link below.
http://forum.e46fanatics.com/showthr...0#post14551400
As an aside, I don't think the Audi transmissions have the same reverse fail problems that other ZF 5HP19 transmissions have. The reverse drum that fails is a different design on the Audi transmissions, which is most likely a result of failures on other cars.
08-22-2013, 10:16 AM
#12
AudiWorld Member
Thread Starter
I was in cruise, and it did cancel the cruise control, then once the
RPM's dropped back down (went back into 5th gear) I re-engaged the cruise, and everything worked normally from there on till it did it again when my wife was driving in town.....roughly 500 miles later.
jjrichar, your information makes complete sense to me, I've felt all along that it was probably an electronics issue but didn't have a clue where to start looking, thanks for taking the time to write up such an informative post. I'm going to try your solution (although it hasn't acted up since it did it that second time to my wife) anyway, and see what happens. It does make sense that it went into 4th gear, the amount of increased revs points directly to that. I thought limp mode was third gear, as it is on my MINI automatic.
One question, why do you suppose it would it do it just running down the road? I could see it acting up as you shifted the lever, but when we'd been on the highway for hours at mostly constant speed? Why would it choose to do it then? Can you reach the switch enough to spray some contact cleaner into it, perhaps if you remove the rear crossmember?
What about moisture incursion? We'd been thru a huge storm a few days before, tho no water after that. We didn't drive thru any deep water or anything, ford any streams or such, but it was an amazing storm, huge wind, rain driven sideways and so on....
Lastly, one small piece of info that may have been glossed over or may not have any import to this - when it did it to me the "suspension" warning light in the cluster lit up. It went back out fairly quickly and hasn't lit since. The suspension has always worked normally, before this event and since. I don't know if the light lit up when it did it to my wife.....in this photo it's the symbol of the car with the arrows, in the tach above the pointer's center. No other lights lit up (this is not a pic from my car)
I need someone in the KC area with a VAG-COM, badly.....
RPM's dropped back down (went back into 5th gear) I re-engaged the cruise, and everything worked normally from there on till it did it again when my wife was driving in town.....roughly 500 miles later.
jjrichar, your information makes complete sense to me, I've felt all along that it was probably an electronics issue but didn't have a clue where to start looking, thanks for taking the time to write up such an informative post. I'm going to try your solution (although it hasn't acted up since it did it that second time to my wife) anyway, and see what happens. It does make sense that it went into 4th gear, the amount of increased revs points directly to that. I thought limp mode was third gear, as it is on my MINI automatic.
One question, why do you suppose it would it do it just running down the road? I could see it acting up as you shifted the lever, but when we'd been on the highway for hours at mostly constant speed? Why would it choose to do it then? Can you reach the switch enough to spray some contact cleaner into it, perhaps if you remove the rear crossmember?
What about moisture incursion? We'd been thru a huge storm a few days before, tho no water after that. We didn't drive thru any deep water or anything, ford any streams or such, but it was an amazing storm, huge wind, rain driven sideways and so on....
Lastly, one small piece of info that may have been glossed over or may not have any import to this - when it did it to me the "suspension" warning light in the cluster lit up. It went back out fairly quickly and hasn't lit since. The suspension has always worked normally, before this event and since. I don't know if the light lit up when it did it to my wife.....in this photo it's the symbol of the car with the arrows, in the tach above the pointer's center. No other lights lit up (this is not a pic from my car)
I need someone in the KC area with a VAG-COM, badly.....
Last edited by allroaddave; 08-22-2013 at 10:21 AM.
08-22-2013, 03:20 PM
#13
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I don't have any idea why it would drop into limp mode while driving along, but there might have been a momentary short or something like that. If all electrical power is removed from the transmission electronics, the automatic flow of fluid in this mode with the gear shift in D is to put it in 4th (limp).
The storm might have something to do with it. The switch on the side of the transmission is a sealed unit, and so I would guess the problem isn't here. Running it through the gears like a described before isn't going to hurt though.
I would take a good look at the plug. It should be accessible under the car. Disconnect it, and give both sides a good cleanout and blow with compressed air. Connect and disconnect a whole bunch of times to ensure you have a good connection. There is a large O ring around the inside of the plug that is supposed to keep it sealed, but with time this may have let some moisture in. A spray from the outside is going to do nothing.
Note there are two plugs on the transmission. One goes to the internal solenoids and sensors, and the other goes to the switch I'm talking about. Personally I'd give both a good clean. The problem could be on either.
If you don't have easy access to VAG-COM, I would advise purchasing VCDS. It's a great tool, and I use it far more than I ever thought I would.
No idea why the suspension light came on. There is so much interconnectivity between different elements in the car, it's sometimes hard to know what intermittent or multiple warning lights mean.
The storm might have something to do with it. The switch on the side of the transmission is a sealed unit, and so I would guess the problem isn't here. Running it through the gears like a described before isn't going to hurt though.
I would take a good look at the plug. It should be accessible under the car. Disconnect it, and give both sides a good cleanout and blow with compressed air. Connect and disconnect a whole bunch of times to ensure you have a good connection. There is a large O ring around the inside of the plug that is supposed to keep it sealed, but with time this may have let some moisture in. A spray from the outside is going to do nothing.
Note there are two plugs on the transmission. One goes to the internal solenoids and sensors, and the other goes to the switch I'm talking about. Personally I'd give both a good clean. The problem could be on either.
If you don't have easy access to VAG-COM, I would advise purchasing VCDS. It's a great tool, and I use it far more than I ever thought I would.
No idea why the suspension light came on. There is so much interconnectivity between different elements in the car, it's sometimes hard to know what intermittent or multiple warning lights mean.
09-11-2013, 09:18 AM
#16
AudiWorld Member
Thread Starter
Update #4
another 2 weeks and not a hint of trouble, I'm beginning to think it might just have been the Garmin dongle that upset the electronics after all. I've driven it hard, I've driven it easy, in the city, on the highway, towed my small trailer and all it's done is work perfectly.
I'm somewhat relieved, the wife is driving it to work again and I think we just dodged an expensive bullet.
another 2 weeks and not a hint of trouble, I'm beginning to think it might just have been the Garmin dongle that upset the electronics after all. I've driven it hard, I've driven it easy, in the city, on the highway, towed my small trailer and all it's done is work perfectly.
I'm somewhat relieved, the wife is driving it to work again and I think we just dodged an expensive bullet.
09-11-2013, 10:56 AM
#17
AudiWorld Senior Member
As for versions...you only need the latest, tho older versions work fine; it's not like these cars need the newest version.
09-11-2013, 01:28 PM
#18
AudiWorld Super User
The software is free and you can prolly find a cable on ebay much less than retail from Ross-Tech. You really NEED this if you have a VAG (VW/Audi Group)product.
As for versions...you only need the latest, tho older versions work fine; it's not like these cars need the newest version.
As for versions...you only need the latest, tho older versions work fine; it's not like these cars need the newest version.
10-06-2015, 08:05 PM
#19
AudiWorld Member
Thread Starter
Follow Up:
Here we are abut 2 years on and the good news is the transmission has never missed a beat since. I always wonder about things like this, but I'm going to just carry on with and drive it......
The car hasn't put a wheel wrong in the last two years, tho I did have to replace one of the 5 year old Arnott air bags this year.
Here we are abut 2 years on and the good news is the transmission has never missed a beat since. I always wonder about things like this, but I'm going to just carry on with and drive it......
The car hasn't put a wheel wrong in the last two years, tho I did have to replace one of the 5 year old Arnott air bags this year.
10-19-2015, 07:40 AM
#20
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I just had the same thing happened while driving... the past two weeks it's been slow to start... thinking it's just time for anew battery (5 years old)... do you think that has anything to do with the electronics for the transmission going into limp mode?