Automatic Transmission controller has gone bad???
10-26-2008, 12:13 AM
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Automatic Transmission controller has gone bad???
My latest problem with my lovely, but very troublesome, Audi A4 V6 Quattro is the transmission electronics. Here's the story...
On Friday, I brought my car to a transmission shop to have the ATF fluid checked and an oil leak looked at because I had begun to notice the tranny slipping from 1st to 2nd regularly when the car is first driven from a cold start.. Yes, ATF fluid was low, and the repairs were installing a new ATF fluid pan installed, with new ATF fluid and filter, and for the oil leak, sealant on the Bank 2 knock sensor is where it was coming from.
Okay, that seems like a pretty simple good deed for my car. But now the trouble begins. Driving the car home later in the day, it jerks coming out of the parking space, and later at a red traffic light it is jerking several times while the car is standing still! Great, must be backfiring or something crazy like that. No CEL came on, however, despite the intense frequency at the traffic light.
When I get home and scan the car parked in the garage (engine not running) with VCDS/VAG-COM, there are no misfire codes, but instead just this one:
Address 01: Engine
Control Module Part Number: 4D0 907 551 AH
Component and/or Version: 2.8L V6/5V MOTR AT D01
Software Coding: 06251
Work Shop Code: WSC 06335
1 Fault Found:
18034 - Powertrain Data Bus: Missing Message from TCU
P1626 - 35-10 - - - Intermittent
I've seen that code just once before on this car, and that was 4 months ago. Checking the transmission controller next, no codes stored. I figure since he was working on the transmission, he must have had to unplug wires and that's all that code is about.
But then as I'm shutting down the laptop, I notice a clicking noise. It's the red light on the gear shift, indicating the gear shift lock is active and you must press brake to shift out of park. It is going on and off all by itself, even without the engine running. Is my brake light switch going screwy? Brake light is not flickering on the closed garage door, however. Then the shift lock light goes out and stays out!
I go back into the VCDS and try to open the transmission controller, but the controller isn't responding. Then the red shift lock light comes back on, I try to open the auto transmission controller again, this time I can get in, but then the shift lock light goes out and the connection with the controller is broken.
Hmm, looks like we have a short in the transmission controller circuit! Probably oil on the transmission electrical connector contacts I figure. I bring the car back to the transmission shop that worked on my fluids. The shift lock light is no longer flickering, but this code is now stored in the transmission controller:
Address 02: Auto Trans
Control Module Part Number: 8D0 927 156 BQ
Component and/or Version: AG5 01V 2.8l5V USA 8511
Software Coding: 00000
Work Shop Code: WSC 00000
1 Fault Found:
01044 - Control Module Incorrectly Coded
35-00 - -
What kind of bullsh*t code is that? The coding on the module is 00000, the same as it has always been (and the factory default too!). Okay, let's have the guy look at the car he worked on yesterday. He checks the trabsmission wiring, and yep he says there is oil on them and he cleans them off and everything looks good to him (and he also says he never even disconnected them when he was working on the car the previous day). Okay, great, that should fix it!
Unfortunately, however, before I even get to start the car, the shift lock light is switching itself off again. I bring him back over to see it. He notices my brake light switch doesn't respond quickly like it should, but otherwise what's going on seems puzzling. We figure it will go away over the weekend. I hope it doesn't get worse, anyway. I clear the "Control Module Incorrectly Coded" fault and drive home and the ride seems fairly normal.
When I get home, the "Control Module Incorrectly Coded" error is back, but the shift lock light is not going off anymore. Weird, the only other coding possible for this car (non-DBW) is to disable the Driving Shift Program (00010). But before I do that, let's just see how long it takes for this code to come back. I clear it. The turn the key to OFF and back to ON and re-open the module (engine has never been running), the fault code is back already.
Okay, that code has nothing to do with driving, and I've never seen it before and the coding has always been (and still is) 00000. Let's try just re=saving the coding to 00000 and resetting all factory defaults using adaptation channel 0. Turn off the ignition and then back on again, now this weird fault code is not coming back anymore. Great! Guess the flash memory must have gotten internally corrupted from the electrical short we just cleaned up. Take the car for a drive, no problems, no codes thrown, the shift lock light is not going out by itself anymore.
Later in the day, however, the shift lock light is going out on its own more, and in fact it is taking a very long time to come back on. I guess I'm going to have to pull up the carpet and take out the transmission controller (which is GIAC chipped) and test the wires to prove that a short is the problem and it is in wiring going down to the transmission. I guess the transmission controller has no fault code for unexpected loss of power (the ECU does, however).
Several hours later, there is no wetness down there, and I've tested most of the wires going into or out of the transmission controller's 88-pin connector according to some unusually detailed instructions in the Bentley manual, I have not once seen a twitch in signal or any sign of a weak or intermittent connection (the wires I didnt check are the CAN bus, dual K line, and the signals the TCU gets from the ECU). The transmission controller has strong, continuous power supply when the ignition is ON (as a sidenote, it turns out that the automatic transmission controller runs on the same electrical circuit as the instrument cluster and a bunch of other electronics, so if it is losing power, there would be other problems). What the hell!
I plug the transmission controller back in. The shift lock light still won't come on and I can't access the controller. I'm beginning to wonder if it ever will come on again. I even start the engine (hello Check Engine light!) to no avail. After maybe 5 minutes, the transmission controller does actually come online all on its own. And it now has some more meaningful faults inside it:
Address 02: Auto Trans
Control Module Part Number: 8D0 927 156 BQ
Component and/or Version: AG5 01V 2.8l5V USA 8511
Software Coding: 00000
Work Shop Code: WSC 00000
3 Faults Found:
01236 - Shift Selector Locking Solenoid (N110)
31-10 - Open or Short to Ground - Intermittent
00293 - Multi-function Switch (F125)
27-10 - Implausible Signal - Intermittent
00270 - Solenoid Valve 7 (N94)
28-00 - Short to Plus
Ok, now if I clear those and get them to come back again, we know where the problem is, correct? However, I can never get them to come back again. I can't find any such shorts in these circuits using a multi-tester either. Now I'm really stuck in a hole.
The cause for this message is that I'm beginning to wonder if my transmission controller has become electronically damaged. It seems to me now more like the transmission controller is crashing and rebooting repeatedly. Maybe the problem was caused by a short when there was oil on the connectors, or maybe it is something that's been building up over time anyway (note, I did see an ECU code one day for a lost connection to the TCU 4 months ago, but there was an oil leak then too). Just my luck, of course, that at the same time that I fix one thing, and another goes broken. Or, is it still possible there is something wrong with the wiring on the transmission or a sensor within it? (maybe crazy readings/data are causing the TCU to shut itself down)? I opened the TCU to look at the GIAC chip, it is soldered there very nice and cleanly and tightly, I don't think the connection there has any sort of problem.
Appreciate thoughts on whether the TCU itself is my actual problem (goodbye GIAC if it is, I guess).
On Friday, I brought my car to a transmission shop to have the ATF fluid checked and an oil leak looked at because I had begun to notice the tranny slipping from 1st to 2nd regularly when the car is first driven from a cold start.. Yes, ATF fluid was low, and the repairs were installing a new ATF fluid pan installed, with new ATF fluid and filter, and for the oil leak, sealant on the Bank 2 knock sensor is where it was coming from.
Okay, that seems like a pretty simple good deed for my car. But now the trouble begins. Driving the car home later in the day, it jerks coming out of the parking space, and later at a red traffic light it is jerking several times while the car is standing still! Great, must be backfiring or something crazy like that. No CEL came on, however, despite the intense frequency at the traffic light.
When I get home and scan the car parked in the garage (engine not running) with VCDS/VAG-COM, there are no misfire codes, but instead just this one:
Address 01: Engine
Control Module Part Number: 4D0 907 551 AH
Component and/or Version: 2.8L V6/5V MOTR AT D01
Software Coding: 06251
Work Shop Code: WSC 06335
1 Fault Found:
18034 - Powertrain Data Bus: Missing Message from TCU
P1626 - 35-10 - - - Intermittent
I've seen that code just once before on this car, and that was 4 months ago. Checking the transmission controller next, no codes stored. I figure since he was working on the transmission, he must have had to unplug wires and that's all that code is about.
But then as I'm shutting down the laptop, I notice a clicking noise. It's the red light on the gear shift, indicating the gear shift lock is active and you must press brake to shift out of park. It is going on and off all by itself, even without the engine running. Is my brake light switch going screwy? Brake light is not flickering on the closed garage door, however. Then the shift lock light goes out and stays out!
I go back into the VCDS and try to open the transmission controller, but the controller isn't responding. Then the red shift lock light comes back on, I try to open the auto transmission controller again, this time I can get in, but then the shift lock light goes out and the connection with the controller is broken.
Hmm, looks like we have a short in the transmission controller circuit! Probably oil on the transmission electrical connector contacts I figure. I bring the car back to the transmission shop that worked on my fluids. The shift lock light is no longer flickering, but this code is now stored in the transmission controller:
Address 02: Auto Trans
Control Module Part Number: 8D0 927 156 BQ
Component and/or Version: AG5 01V 2.8l5V USA 8511
Software Coding: 00000
Work Shop Code: WSC 00000
1 Fault Found:
01044 - Control Module Incorrectly Coded
35-00 - -
What kind of bullsh*t code is that? The coding on the module is 00000, the same as it has always been (and the factory default too!). Okay, let's have the guy look at the car he worked on yesterday. He checks the trabsmission wiring, and yep he says there is oil on them and he cleans them off and everything looks good to him (and he also says he never even disconnected them when he was working on the car the previous day). Okay, great, that should fix it!
Unfortunately, however, before I even get to start the car, the shift lock light is switching itself off again. I bring him back over to see it. He notices my brake light switch doesn't respond quickly like it should, but otherwise what's going on seems puzzling. We figure it will go away over the weekend. I hope it doesn't get worse, anyway. I clear the "Control Module Incorrectly Coded" fault and drive home and the ride seems fairly normal.
When I get home, the "Control Module Incorrectly Coded" error is back, but the shift lock light is not going off anymore. Weird, the only other coding possible for this car (non-DBW) is to disable the Driving Shift Program (00010). But before I do that, let's just see how long it takes for this code to come back. I clear it. The turn the key to OFF and back to ON and re-open the module (engine has never been running), the fault code is back already.
Okay, that code has nothing to do with driving, and I've never seen it before and the coding has always been (and still is) 00000. Let's try just re=saving the coding to 00000 and resetting all factory defaults using adaptation channel 0. Turn off the ignition and then back on again, now this weird fault code is not coming back anymore. Great! Guess the flash memory must have gotten internally corrupted from the electrical short we just cleaned up. Take the car for a drive, no problems, no codes thrown, the shift lock light is not going out by itself anymore.
Later in the day, however, the shift lock light is going out on its own more, and in fact it is taking a very long time to come back on. I guess I'm going to have to pull up the carpet and take out the transmission controller (which is GIAC chipped) and test the wires to prove that a short is the problem and it is in wiring going down to the transmission. I guess the transmission controller has no fault code for unexpected loss of power (the ECU does, however).
Several hours later, there is no wetness down there, and I've tested most of the wires going into or out of the transmission controller's 88-pin connector according to some unusually detailed instructions in the Bentley manual, I have not once seen a twitch in signal or any sign of a weak or intermittent connection (the wires I didnt check are the CAN bus, dual K line, and the signals the TCU gets from the ECU). The transmission controller has strong, continuous power supply when the ignition is ON (as a sidenote, it turns out that the automatic transmission controller runs on the same electrical circuit as the instrument cluster and a bunch of other electronics, so if it is losing power, there would be other problems). What the hell!
I plug the transmission controller back in. The shift lock light still won't come on and I can't access the controller. I'm beginning to wonder if it ever will come on again. I even start the engine (hello Check Engine light!) to no avail. After maybe 5 minutes, the transmission controller does actually come online all on its own. And it now has some more meaningful faults inside it:
Address 02: Auto Trans
Control Module Part Number: 8D0 927 156 BQ
Component and/or Version: AG5 01V 2.8l5V USA 8511
Software Coding: 00000
Work Shop Code: WSC 00000
3 Faults Found:
01236 - Shift Selector Locking Solenoid (N110)
31-10 - Open or Short to Ground - Intermittent
00293 - Multi-function Switch (F125)
27-10 - Implausible Signal - Intermittent
00270 - Solenoid Valve 7 (N94)
28-00 - Short to Plus
Ok, now if I clear those and get them to come back again, we know where the problem is, correct? However, I can never get them to come back again. I can't find any such shorts in these circuits using a multi-tester either. Now I'm really stuck in a hole.
The cause for this message is that I'm beginning to wonder if my transmission controller has become electronically damaged. It seems to me now more like the transmission controller is crashing and rebooting repeatedly. Maybe the problem was caused by a short when there was oil on the connectors, or maybe it is something that's been building up over time anyway (note, I did see an ECU code one day for a lost connection to the TCU 4 months ago, but there was an oil leak then too). Just my luck, of course, that at the same time that I fix one thing, and another goes broken. Or, is it still possible there is something wrong with the wiring on the transmission or a sensor within it? (maybe crazy readings/data are causing the TCU to shut itself down)? I opened the TCU to look at the GIAC chip, it is soldered there very nice and cleanly and tightly, I don't think the connection there has any sort of problem.
Appreciate thoughts on whether the TCU itself is my actual problem (goodbye GIAC if it is, I guess).
10-26-2008, 12:18 AM
#2
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Re: Automatic Transmission controller has gone bad???
Another important question too:
Can I drive my car safely without the transmission control module installed? Will the automatic transmission operate in "limp" mode in this circumstance, and what is the problem with using "limp" mode until I get this issue fixed?
I think I'd much rather be in limp mode all the time than possibly switching in and out of limp mode while driving on a highway! (or is the loud bang noise when that happens okay?)
Can I drive my car safely without the transmission control module installed? Will the automatic transmission operate in "limp" mode in this circumstance, and what is the problem with using "limp" mode until I get this issue fixed?
I think I'd much rather be in limp mode all the time than possibly switching in and out of limp mode while driving on a highway! (or is the loud bang noise when that happens okay?)
10-26-2008, 02:18 AM
#3
Are you saying that oil was leaking from an oxygen sensor?
It is not "save" to drive around in limp mode; it's bad for the torque converter. Make sure your TCU is all set inside and clean all connections. Recheck fluid level.
10-26-2008, 06:38 AM
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OIl was leaking from the knock sensor
Limp mode is not safe? Sh*t.
You think it is safer to drive around possibly falling into and out of limp mode? At high speeds it is a particularly loud noise when the system switches itself on and off.
You think it is safer to drive around possibly falling into and out of limp mode? At high speeds it is a particularly loud noise when the system switches itself on and off.
10-26-2008, 09:16 AM
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I drove a limpy 99 Tip for awhile before swapping the trans. Mine was going into limp as soon as
it hit 3th gear, IIRC. I used the tip to keep it 2nd. found that I could skip 3rd by bumping the tip 2x at the right rpm, thus not triggering the limp mode.
my limp mode would reset if I turned the ignition off.
my limp mode would reset if I turned the ignition off.
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10-26-2008, 10:21 AM
#8
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My limp mode happens without regard to gear
The auto trans controller is switching itself on and off by itself without the engine running, while stopped at a red light in DRIVE, while going REVERSE, as well as randomly while moving at any speed. Sometimes it even briefly flickers off and then comes back online immediately.
Car runs fine while the transmission controller is online. The scariest part is the loud thump when it goes offline and the solenoids are all released.
Car runs fine while the transmission controller is online. The scariest part is the loud thump when it goes offline and the solenoids are all released.
10-26-2008, 12:30 PM
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sounds like it's time to try a new TCM.
Chase at A&P always treats me right on stuff like this:<ul><li><a href="http://www.ap-specialties.com/">http://www.ap-specialties.com/</a</li></ul>
10-26-2008, 01:55 PM
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My feelings too, bye bye GIAC chip
Seems like my existing TCM is crashing, hanging, and rebooting or having memory problems or internal power supply issues.
Maybe the GIAC chip has been damaged?
What I just don't get, however, is why it decides to pull this on me immediately after it leaves a transmission service shop for AFT fluid service. The condition has only gotten worse as I run the car more.
Maybe the GIAC chip has been damaged?
What I just don't get, however, is why it decides to pull this on me immediately after it leaves a transmission service shop for AFT fluid service. The condition has only gotten worse as I run the car more.