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Thread: Transmission unresponsive after LIMP mode..... P1850

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    Registered User sbcrc86's Avatar
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    Mech Transmission unresponsive after LIMP mode..... P1850

    I was doing a bit of spirited driving in the rain, hit a bump in the street and transmission went into limp mode. I pulled over restarted the car and LIMP mode was gone but vehicle is unresponsive when shifted into gear. After getting towed I hooked up VCDS and it shows the transmission storing code:
    Powertrain Data Bus
    P1850-003 Missing message from ECU- Intermittent

    Honestly the transmission feels like a pressure valve is not allowing for proper flow of trans fluid, the only thing I noticed that may be wrong when I was monitoring data is that the input speed on the transmission is reading ZERO at idle, is this normal? Does anybody know of any relays or fuses that should be checked or of failures known to have these symptoms.

  2. #2
    Registered User lswing's Avatar
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    Sounds like it's unplugged from the TCU? Check trans connection at trans body, check TCU under passenger floor mat.
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

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    Registered User sbcrc86's Avatar
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    I checked both and have even dropped transmission pan to inspect for disconnected electrical connections inside the transmission for issues or damaged internals and everything looks good. TCU is perfectly dry and shows no signs it was ever wet.

  4. #4
    Registered User TozoM8's Avatar
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    Yes, it should be 0 rpm unless the car is moving.
    05 Cayenne turbo

  5. #5
    Registered User lswing's Avatar
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    Quote Originally Posted by TozoM8 View Post
    Yes, it should be 0 rpm unless the car is moving.
    You're back! Trans is doing great, and I'm not beating the crap out of it
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

  6. #6
    Registered User lswing's Avatar
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    This was your fix right, loose/broken wire to ECU? http://www.rs6.com/showthread.php/31...-bad-ECU-help-!
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

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    Registered User sbcrc86's Avatar
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    That was the fix for a downstream O2 sensor that was unresponsive. This new issue does not seem to be so easy. Its as if when LIMP mode was triggered it corrupted a data dump in ECU or TCU. The question now is which one is damaged. Does anybody have the pinout for the TCU?

  8. #8
    Registered User sbcrc86's Avatar
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    Honestly these PIA transmission problems have me taking a hard look at 01E.

  9. #9
    Registered User lswing's Avatar
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    Quote Originally Posted by sbcrc86 View Post
    Honestly these PIA transmission problems have me taking a hard look at 01E.
    Your auto trans problem sounds unique though, first I've heard of, wiring would be a great fix. Mine just have the problem of breaking internally...
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

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    Registered User MaxRS6's Avatar
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    Quote Originally Posted by lswing View Post
    ...Mine just have the problem of breaking internally...
    +1- I got the shaft with the shaft break last time. All of the king's wiring men could not put Humpty back together...Ooofff


    210K miles rolled

  11. #11
    Registered User sbcrc86's Avatar
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    I have a feeling that may be what's wrong with mine

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    Registered User marklar182's Avatar
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    There is a good trans out of my totaled car in the classifieds.
    2008 A4 2.0TQ Quartz Grey Metallic S-Line/Titanium Package
    2017 A4 2.0TQ Glacier White Metallic Prestige Sport
    2003 RS6 TOTALED.-----Searching for a replacement

  13. #13
    Registered User sbcrc86's Avatar
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    I replaced my trans a little over a year ago with a brand new unit from audi so it's supposed to be under warrantee. I'll get the replacement and sell it to fund 01e swap.

  14. #14
    Registered User sbcrc86's Avatar
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    Click image for larger version. 

Name:	IMG_0819.jpg 
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ID:	15742Here is the issue, sheered off input shaft.

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    Quote Originally Posted by sbcrc86 View Post
    Here is the issue, sheered off input shaft.

    Look at that break. That's defective! Improper manufacture. That part was brittle from day one, destined to break exactly as it did.

  16. #16
    Registered User lswing's Avatar
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    Crap, at least you found it. Not sure if it wasn't just stress over time. It's only 11 years old after all. What's your mileage for reference, and tuned at all for xxx miles?
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

  17. #17
    Registered User sbcrc86's Avatar
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    My mileage is 109k but I replaced the transmission with a 4500 unit from the dealer. 01E has been initiated, have the adapter kit ordered. After seeing the failure there is no way I am installing another ZF in the car.

  18. #18
    Registered User sbcrc86's Avatar
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    Stage 2 unitronic putting 430whp and 493ftlb@wheels.

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