Occasional Limp Mode Question

[davej]

My car will start up/run fine, but occasionally when I shift out of park into drive or reverse for the first time, there will be a delay of 2-3 seconds, then a huge jolt as the car slams into gear. The cluster lights up PRNDS in solid red, which I'd guess is the tcu putting the car into limp mode?

It typically happens in the morning when leaving for work and the car has sat all night, but bit every time. I can shut the car off/on and usually everything is fine after that. A few times I had to restart the car 2 or 3 times.

I thought it was my tcu going bad so I swapped the stock one in for one with a. Giac chip, but still have the same issue occasionally. (No more/less frequent though)

No CEL or codes to be read when it happens. Any suggestions on where to start looking??

This is the second transmission, first was replaced at 50k by Audi and the car has 85k now.

Thanks for any ideas!

[mrdave]

Are you reading codes from the TCU also or just the ECU?

My initial thought would be valve body in the trans.

[hahnmgh63]

In addition to what mrdave said you may also want to have your tranny fluid level checked. Even if it was done by the dealer it can be tricky, especially since it was a new tranny and completely empty. I fill the tranny per the procedure then drive it a quarter mile or so, then shut it down and let it cool a bit then re-check it again. Almost always has a too little as the air is purged out of all the lines.

[davej]

Thanks! I'll check the fluid level and hit the Ross tech wiki to see if there's any different way to scan the tcu, and report back any codes I may find in it.

[davej]

Yesterday the car went into limp 3x in a row and finally my face was warmed by the glow of the much beloved CEL.

Here's a dump of the vcds tcu and auto scan. Clearly some other electrical gremlins going on, so please feel free to comment on anything that stand out to you. (the car had already been wired for an RSN-E so looks like I'll have to dig into that a bit at some point)
Looks like the transmission range sensor is a common spot to get gunked up and replacing didn't look too bad when I was under it today. Does anyone have a preferred source for these?
I think the advice above to drain/fill the trans fluid is good as well, I'll start prepping for that as well.


--------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01L-927-156.lbl
Control Module Part Number: 4B0 927 156 FL
Component and/or Version: AG5 01L 4.2l5VT USA 0305
Software Coding: 0000002
Work Shop Code: WSC 00000 785 00200
VCID: 76B51849D4D26347B49-5160
2 Faults Found:


17090 - Transmission Range Sensor (F125)
P0706 - 003 - Implausible Signal - Intermittent - MIL ON
17087 - Brake Switch (F)
P0703 - 003 - Electrical Malfunction - Intermittent

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

Address 02: Auto Trans
Control Module Part Number: 4B0 927 156 FL
Component and/or Version: AG5 01L 4.2l5VT USA 0305
Software Coding: 0000002
Work Shop Code: WSC 00000
VCID: 76B51849D4D26347B49-5160


Flash Status
Programming Attempts: 0
Successful Attempts: 0
Programming Status: 00000000
Required Conditions: 00000000
Misc.
VCDS Info:
VCID: 76B51849D4D26347B49-5160
Labels: 01L-927-156.LBL

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

Wednesday,10,October,2018,13:51:07:21999
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 18.9.0.2 (x64) HEX-V2 CB: 0.4436.4
Data version: 20180927 DS296.0
www.Ross-Tech.com (http://www.Ross-Tech.com)

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

Chassis Type: 4B (4B - Audi A6/S6/RS6/allroad C5 (1998 > 2005))
Scan: 01 02 03 06 08 15 16 17 18 22 34 35 36 37 45 55 56 57 65 67
75 76 77

VIN: WUAPV64B03N904777
-------------------------------------------------------------------------------
Address 01: Engine Labels: 077-907-558-BCY.lbl
Part No: 4D1 907 558
Component: 4.2l V8/5VT G 0002
Coding: 0006752
Shop #: WSC 65728 1018 854933
VCID: 6B83393D9F90AEAF5B7-5160


2 Faults Found:
18032 - MIL Request Signal Active (Check TCM for errors too!)
P1624 - 008 -
16955 - Brake Switch (F)
P0571 - 008 - Implausible Signal - Intermittent
Readiness: 0000 1100


-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01L-927-156.lbl
Part No: 4B0 927 156 FL
Component: AG5 01L 4.2l5VT USA 0305
Coding: 0000002
Shop #: WSC 00000 785 00200
VCID: 76B51849D4D26347B49-5160


2 Faults Found:
17090 - Transmission Range Sensor (F125)
P0706 - 003 - Implausible Signal - Intermittent - MIL ON
17087 - Brake Switch (F)
P0703 - 003 - Electrical Malfunction - Intermittent

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: None
VCID: 55F77FC52C14085F9D3-51F2

No Faults Found
or DTCs not supported by controller
or a communication error occurred

-------------------------------------------------------------------------------
Address 06: Seat Mem. Pass Labels: None
Part No: 4B0 959 760 C
Component: Sitzmemory R1 BF 0205
Coding: 00003
Shop #: WSC 00000
VCID: 2D07F7256434609F053-4AE0

1 Fault Found:
01731 - Switch for Seat Height Front Pass. Seat (E65); Down
28-10 - Short to Plus - Intermittent

-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 4B0-820-043-MY2.lbl
Part No: 4B0 820 043 AR
Component: A6-Klimavollautomat 0208
Coding: 00010
Shop #: WSC 00000
VCID: 6A8D3C39955AB7A7201-2578


3 Faults Found:
00779 - Outside Air Temp Sensor (G17)
30-10 - Open or Short to Plus - Intermittent
00819 - High Pressure Sensor (G65)
30-10 - Open or Short to Plus - Intermittent
01592 - Air Quality Sensor (G238)
57-00 - Electric Circuit Failure

-------------------------------------------------------------------------------
Address 15: Airbags Labels: 4B0-959-655-AI84.lbl
Part No: 4B0 959 655 Q
Component: Airbag 8.4EP 3001
Coding: 0000607
Shop #: WSC 00000 785 00200
VCID: 3E25C069BC62EB07AC9-5184


No fault code found.
-------------------------------------------------------------------------------
Address 17: Instruments Labels: 4B0-920-xxx-17.lbl
Part No: 4B0 920 983 D
Component: KOMBI+WEGFAHRS. VDO D12
Coding: 03284
Shop #: WSC 07117
VCID: 290F033550EC7CBFE9B-5160
WUAPV64B03N904777 AUZ7Z0C2424830


1 Fault Found:
01311 - Information Data Bus
80-00 - Single-Wire Operation


-------------------------------------------------------------------------------
Address 35: Centr. Locks Labels:. 4B0-962-258.lbl
Part No: 4B0 962 258 M
Component: Central Lock/Alarm D38
Coding: 15981
Shop #: WSC 00000
VCID: 3333E15D8210366F537-4EEA


1 Fault Found:
01562 - Rear right door
59-10 - Can't Unlock - Intermittent


-------------------------------------------------------------------------------
Address 36: Seat Mem. Drvr Labels: None
Part No: 4B0 959 760 B
Component: Sitzmemory R1 F 0204
Coding: 00001
Shop #: WSC 00000
VCID: 2C01FA215F2E699712D-4AE0


5 Faults Found:
01445 - Sensor for Driver Seat Fore/Aft (G227)
29-10 - Short to Ground - Intermittent
01446 - Sensor for Driver Seat; Seatback Adjust (G230)
29-10 - Short to Ground - Intermittent
01447 - Sensor for Driver Seat; Height Adjust (G231)
29-10 - Short to Ground - Intermittent
01448 - Sensor for Driver Seat; Tilt Adjust (G232)
29-10 - Short to Ground - Intermittent
01446 - Sensor for Driver Seat; Seatback Adjust (G230)
20-00 - Malfunction in Basic Setting


-------------------------------------------------------------------------------
Address 37: Navigation Labels: 8E0-035-192-RNSE.clb
Part No SW: 8P0 035 192 HW: 8P0 035 192
Component: RNS-E US H72 0260
Revision: 08S Serial number: AUZBZ7E0370945
Coding: 0509678
Shop #: WSC 11111 781 01234
VCID: 6C813A219AAEA99752D-5118


6 Faults Found:
00532 - Supply Voltage B+
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 7
Fault Frequency: 1
Reset counter: 50
Time Indication: 0
Date: 2018.05.31
Time: 10:29:58


Freeze Frame:
Voltage: 12.20 V


00446 - Function Limitation due to Under-Voltage
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 7
Fault Frequency: 1
Reset counter: 50
Time Indication: 0
Date: 2018.05.31
Time: 10:12:35


Freeze Frame:
Voltage: 12.20 V
Mileage: 655350 km
Count: 65535
Clock: 255:255


00858 - Connection; Radio Intermediate Frequency (IF) Output to Antenna Amplifier
007 - Short to Ground - Intermittent
Freeze Frame:
Fault Status: 00100111
Fault Priority: 5
Fault Frequency: 211
Reset counter: 50
Time Indication: 0
Date: 2018.05.31
Time: 12:01:17


Freeze Frame:
Mileage: 655350 km
Count: 1010
Clock: 13:33


00857 - CD Changer Unit (R41)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 5
Fault Frequency: 1
Reset counter: 160
Time Indication: 0
Date: 2018.05.16
Time: 21:00:32


01326 - Control Module for Multi-Function Steering Wheel (J453)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 5
Fault Frequency: 1
Reset counter: 160
Time Indication: 0
Date: 2018.05.16
Time: 20:59:48


00467 - TV Tuner (R78)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 5
Fault Frequency: 1
Reset counter: 160
Time Indication: 0
Date: 2018.05.16
Time: 21:01:01




-------------------------------------------------------------------------------
Address 55: Headlight Range Labels: 4Z7-907-357.lbl
Part No: 4Z7 907 357
Component: dynamische LWR D09
Coding: 00040
Shop #: WSC 00000
VCID: 04517281973E41D7BAD-4B1E


No fault code found.


-------------------------------------------------------------------------------
Address 56: Radio Labels: 8E0-035-192-RNSE.clb
Part No SW: 8P0 035 192 HW: 8P0 035 192
Component: RNS-E US H72 0260
Revision: 08S Serial number: AUZBZ7E0370945
Coding: 0509678
Shop #: WSC 11111 781 01234
VCID: 6C813A219AAEA99752D-5118


6 Faults Found:
00532 - Supply Voltage B+
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 7
Fault Frequency: 1
Reset counter: 50
Time Indication: 0
Date: 2018.05.31
Time: 10:29:58


Freeze Frame:
Voltage: 12.20 V


00446 - Function Limitation due to Under-Voltage
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 7
Fault Frequency: 1
Reset counter: 50
Time Indication: 0
Date: 2018.05.31
Time: 10:12:35


Freeze Frame:
Voltage: 12.20 V
Mileage: 655350 km
Count: 65535
Clock: 255:255


00858 - Connection; Radio Intermediate Frequency (IF) Output to Antenna Amplifier
007 - Short to Ground - Intermittent
Freeze Frame:
Fault Status: 00100111
Fault Priority: 5
Fault Frequency: 211
Reset counter: 50
Time Indication: 0
Date: 2018.05.31
Time: 12:01:17


Freeze Frame:
Mileage: 655350 km
Count: 1010
Clock: 13:33


00857 - CD Changer Unit (R41)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 5
Fault Frequency: 1
Reset counter: 160
Time Indication: 0
Date: 2018.05.16
Time: 21:00:32


01326 - Control Module for Multi-Function Steering Wheel (J453)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 5
Fault Frequency: 1
Reset counter: 160
Time Indication: 0
Date: 2018.05.16
Time: 20:59:48


00467 - TV Tuner (R78)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 5
Fault Frequency: 1
Reset counter: 160
Time Indication: 0
Date: 2018.05.16
Time: 21:01:01

-------------------------------------------------------------------------------
Address 75: Telematics Labels: 8E0-035-616.lbl
Part No SW: 8E0 035 616 A HW: 8E0 035 616 A
Component: Telematik USA1
Coding: 0002003
Shop #: WSC 07117 444 53517
VCID: 2313111D37C0A6EFA37-513C


2 Faults Found:
01531 - Emergency Battery
002 - Lower Limit Exceeded - MIL ON
00469 - Infotainment Databus in Single Wire Operation
012 - Electrical Fault in Circuit - MIL ON


-------------------------------------------------------------------------------
Address 76: Park Assist Labels: 8Z0-919-283.lbl
Part No: 8Z0 919 283
Component: Parkingsyst. A6 RDW D08
Coding: 01116
Shop #: WSC 00000
VCID: 025D74998D2A4FE7881-5118


No fault code found.


End----------(Elapsed Time: 04:40, VBatt start/end: 12.1V/11.9V)-----------

[mrdave]

Found this http://www.rs6.com/showthread.php/25526-What-are-the-chances?p=246686&viewfull=1#post246686

[davej]

Brilliant!! The op in that thread was the previous owner of my car! Perhaps he never replaced the switch after all.
I'll double check connections, but probably cheap maintaince to swap it out.

Thanks again! And if you guys have any insight into all the other electrical oddities in the codes, I'm all ears :)