2001 audi a6 c5 4.2L Trnsmission gremlin

[Gogo]

Looking for information on the probable cause of the gear selection display all lit up after starting the car. After starting the car the gear display all lights up and there is not any box around P. While it is running and foot on the brake the gear shift lever is move through the gears several times. The car is then shut off and restarted. The box appears around the P and the transmission acts normal without any loss of the indicator of the gear selected. After returning the shift lever to park the box is around P. The car is shut off and when the car is restarted the box high lighting the gear has gone and the PRNDS are high lighted in red.
The TCM has been changed as the original was water logged. Identical part number. The range selector on the side of the transmission has been changed also. When scanning the transmission info does not come up. Lack off communication.
It would appear to be a voltage drop that triggers the issue but from where? Does anyone have any information on the shaft that drives the range selector. Is it possible the shaft has some play and on initial start up moves the range selector slightly causing a loss of contact in the range selector. The MAF has also been mentioned on the web as a possible cause of the issue.

If anyone has any insight as to the possible cause of the issue it would be appreciated.

 

[PetrolDave]

Several possible causes, please post an Auto-Scan

 

[Gogo]

PRND etc all lit up and no box or high light around any gear after starting the car causing limp mode. I found if you quickly turned the key to startthe car before the dash lit up the transmission would act normally and indicate the gear selected. Sometimes it would take 3 or 4 attempts.
Code P1624/18032 comes up on the Ross-Tech. It would appear the TCM has issues communicating at start up. Is it possible a drop in voltage is causing the issue when the starter cranks the engine. It is minus 21 C and the issue is more predominant. The TCM was replaced with an ebay used unit. Identical part number. The old TCM was water logged to the point of some contacts being corroded right off. Unfortunately the replacement TCM will not communicate with the Ross-Tech scanner.

Monday,25,November,2024,12:32:36:18730
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 11 x64
VCDS Version: 24.7.1.0 (x64)  HEX-V2 CB: 0.4643.4
Data version: 20240919 DS356.3
www.Ross-Tech.com


VIN: WAUZL54B71N155721   License Plate:
Mileage: 216160km-134315mi   Repair Order:



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


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: WAUZL54B71N155721   Mileage: 216160km-134315miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: None
   Part No: 4D0 907 560 AE
   Component: 4.2l V8/5V      G   0003 
   Coding: 07752
   Shop #: WSC 02324 
   VCID: 698FABB1706D70E2E85-5118
   WAUZL54B71N155721     AUZ7Z0A1835027

1 Fault Found:
18032 - MIL Request Signal Active (Check TCM for errors too!)
            P1624 - 35-00 -
Readiness: 0000 0101

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 8D0-907-389.lbl
   Part No: 8D0 907 389 E
   Component: ABS/ESP allrad      D56 
   Coding: 06397
   Shop #: WSC 12345 
   VCID: 353737C16C55E402BCD-5160

No fault code found.

-------------------------------------------------------------------------------
Address 06: Seat Mem. Pass        Labels: None
   Part No: 4B0 959 760 C
   Component: Sitzmemory R1 BF    0102 
   Coding: 00003
   Shop #: WSC 00000 
   VCID: 2D071FA18405ACC2C4D-4B00

No fault code found.

-------------------------------------------------------------------------------
Address 08: Auto HVAC        Labels: 4B0-820-043-MY1.lbl
   Part No: 4B0 820 043 AH
   Component: A6-Klimavollautomat D65 
   Coding: 00080
   Shop #: WSC 02324 
   VCID: 6099B695835731AA3FB-25BC

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 4B0-959-655-AI8.lbl
   Part No: 4B0 959 655 F
   Component: Airbag Front+Kopf  2002 
   Coding: 00405
   Shop #: WSC 02324 
   VCID: 333309D96221FA32929-5118

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel        Labels: 4B0-907-487.lbl
   Part No: 4B0 907 487 D
   Component: Lenkradelektronik    D03 
   Coding: 00102
   Shop #: WSC 65535 
   VCID: 2D071FA18405ACC2C4D-4FB8

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 4B0-920-xxx-17.lbl
   Part No: 4B0 920 933 B
   Component: C5-KOMBIINSTR. VDO D12  
   Coding: 03383
   Shop #: WSC 00001 
   VCID: 221DFC9DCDDB63BA69F-513C
   WAUZL54B71N155721     AUZ7Z0A1835027

No fault code found.

-------------------------------------------------------------------------------
Address 35: Centr. Locks        Labels:. 4B0-962-258.clb
   Part No: 4B0 962 258 J
   Component: Central Lock/Alarm  D34 
   Coding: 15885
   Shop #: WSC 02324 
   VCID: 303906D59337C12AEFB-4F0C

4 Faults Found:
01366 - Opened Due to Crash Signal
            35-00 - -
01368 - Alarm triggered by Luggage Compartment Switch
            35-00 - -
01559 - Drivers Door
            59-10 - Can't Unlock - Intermittent
01560 - Passenger Door
            59-10 - Can't Unlock - Intermittent

-------------------------------------------------------------------------------
Address 36: Seat Mem. Drvr        Labels: None
   Part No: 4B0 959 760 B
   Component: Sitzmemory R1 F     0101 
   Coding: 00001
   Shop #: WSC 00000 
   VCID: 2C0112A5BF1FA5CAD33-4B00

No fault code found.

-------------------------------------------------------------------------------
Address 45: Inter. Monitor        Labels: 4B0-951-178.lbl
   Part No: 4B0 951 178 A
   Component: Innenraumueberw.    D04 
   Coding: 00101
   Shop #: WSC 02324 
   VCID: 2615E08DA1F39F9A057-50D0

No fault code found.

-------------------------------------------------------------------------------
Address 55: Headlight Range        Labels: 4B0-907-357-DYN.lbl
   Part No: 4B0 907 357 C
   Component: dynamische LWR       D06 
   Coding: 00020
   Shop #: WSC 02324 
   VCID: 2809EEB5ABE789EA37B-4B5C

No fault code found.

End----(Elapsed Time: 04:41, VBatt start/end: 12.3V/11.3V. VIgn 11.2V)-----

 

[Gogo]

Monday,25,November,2024,12:32:36:18730
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 11 x64
VCDS Version: 24.7.1.0 (x64)  HEX-V2 CB: 0.4643.4
Data version: 20240919 DS356.3
www.Ross-Tech.com


VIN: WAUZL54B71N155721   License Plate:
Mileage: 216160km-134315mi   Repair Order:



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


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: WAUZL54B71N155721   Mileage: 216160km-134315miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: None
   Part No: 4D0 907 560 AE
   Component: 4.2l V8/5V      G   0003 
   Coding: 07752
   Shop #: WSC 02324 
   VCID: 698FABB1706D70E2E85-5118
   WAUZL54B71N155721     AUZ7Z0A1835027

1 Fault Found:
18032 - MIL Request Signal Active (Check TCM for errors too!)
            P1624 - 35-00 -
Readiness: 0000 0101

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 8D0-907-389.lbl
   Part No: 8D0 907 389 E
   Component: ABS/ESP allrad      D56 
   Coding: 06397
   Shop #: WSC 12345 
   VCID: 353737C16C55E402BCD-5160

No fault code found.

-------------------------------------------------------------------------------
Address 06: Seat Mem. Pass        Labels: None
   Part No: 4B0 959 760 C
   Component: Sitzmemory R1 BF    0102 
   Coding: 00003
   Shop #: WSC 00000 
   VCID: 2D071FA18405ACC2C4D-4B00

No fault code found.

-------------------------------------------------------------------------------
Address 08: Auto HVAC        Labels: 4B0-820-043-MY1.lbl
   Part No: 4B0 820 043 AH
   Component: A6-Klimavollautomat D65 
   Coding: 00080
   Shop #: WSC 02324 
   VCID: 6099B695835731AA3FB-25BC

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 4B0-959-655-AI8.lbl
   Part No: 4B0 959 655 F
   Component: Airbag Front+Kopf  2002 
   Coding: 00405
   Shop #: WSC 02324 
   VCID: 333309D96221FA32929-5118

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel        Labels: 4B0-907-487.lbl
   Part No: 4B0 907 487 D
   Component: Lenkradelektronik    D03 
   Coding: 00102
   Shop #: WSC 65535 
   VCID: 2D071FA18405ACC2C4D-4FB8

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 4B0-920-xxx-17.lbl
   Part No: 4B0 920 933 B
   Component: C5-KOMBIINSTR. VDO D12  
   Coding: 03383
   Shop #: WSC 00001 
   VCID: 221DFC9DCDDB63BA69F-513C
   WAUZL54B71N155721     AUZ7Z0A1835027

No fault code found.

-------------------------------------------------------------------------------
Address 35: Centr. Locks        Labels:. 4B0-962-258.clb
   Part No: 4B0 962 258 J
   Component: Central Lock/Alarm  D34 
   Coding: 15885
   Shop #: WSC 02324 
   VCID: 303906D59337C12AEFB-4F0C

4 Faults Found:
01366 - Opened Due to Crash Signal
            35-00 - -
01368 - Alarm triggered by Luggage Compartment Switch
            35-00 - -
01559 - Drivers Door
            59-10 - Can't Unlock - Intermittent
01560 - Passenger Door
            59-10 - Can't Unlock - Intermittent

-------------------------------------------------------------------------------
Address 36: Seat Mem. Drvr        Labels: None
   Part No: 4B0 959 760 B
   Component: Sitzmemory R1 F     0101 
   Coding: 00001
   Shop #: WSC 00000 
   VCID: 2C0112A5BF1FA5CAD33-4B00

No fault code found.

-------------------------------------------------------------------------------
Address 45: Inter. Monitor        Labels: 4B0-951-178.lbl
   Part No: 4B0 951 178 A
   Component: Innenraumueberw.    D04 
   Coding: 00101
   Shop #: WSC 02324 
   VCID: 2615E08DA1F39F9A057-50D0

No fault code found.

-------------------------------------------------------------------------------
Address 55: Headlight Range        Labels: 4B0-907-357-DYN.lbl
   Part No: 4B0 907 357 C
   Component: dynamische LWR       D06 
   Coding: 00020
   Shop #: WSC 02324 
   VCID: 2809EEB5ABE789EA37B-4B5C

No fault code found.

End----(Elapsed Time: 04:41, VBatt start/end: 12.3V/11.3V. VIgn 11.2V)-----

 

[Jef]

Sort of a dead end here because the TCM didn't talk... but there are fault codes for a dead (no comm) TCM. Matter of fact, the TCM is yelling to the ECM for help (P1624). I guess my first question would be.. how wet is the TCM?

Are you ever able to get the TCM to talk to VCDS if you scan it directly instead of via Auto-Scan? How is the K-line from the OBDII port (T16a/7) to the TCM (/88)?

 

[EuroX]

Is this a front trak audi a6? with the CVT trans? If so may god have mercy on your soul.

 

[Gogo]

The car is not a CVT. The original TCM was swimming in water and it was replaced with a used TCM with identical part number. I have also tried scanning the TCM directly but to no avail.
I will lift the carpet and remove the TCM. I did clean all the contacts before installation but will do it once again. A pinout for the TCM connector would be helpful.
I also repaired the corroded pins on the old TCM and could try it although given the amount of water involved it may be DOA.

Once the car is not in limp mode the transmission acts and shifts normally. I did also check the oil level and color of the oil. All is fine.

I hate to buy another TCM only to find I have the same issue. The TCM used is quite expensive for an audi A6 C5 4.2L.

Unfamiliar with the K line. Can you fill me in.

Thanks for you input into solving the issue.

 

[PetrolDave]

Unfamiliar with the K line. Can you fill me in.

K line is the diagnostics connection, you need to check if it is connected to the TCM.

 

[Gogo]

Thanks. The R/T does not talk to the TCM when scanning all components or stand alone TCM.

Will put it in my shop today and remove the TCM and look for any obvious issues.

Can I assume it is a TCM issue since the ECM comes up with a trouble code when trying to have a chat with the TCM.

 

[Jef]

Were the terminals at the TCM tarnished, rotted, crusty, or pickle falvored? If a harness has been wet for a while, moisture will get pulled into the harness (capillary effect). This can cause wiring to rot on the inside. I'm 99% sure the TCM is awake and talking to other control module, so power/ground for example are in place (good enough.... currently), but other wiring, such as the K-line and maybe a sensor are rotted.... thus no comm and TCM is in a fail mode.

Hands on the the TCM again and ohm test the K-line as noted in post #2.

 

[Uwe]

Is it safe to assume this car has an automatic transmission? Because if it does, it's not showing up in your scan...

-Uwe-

 

[Uwe]

Is this a front trak audi a6? with the CVT trans?

With a 4.2 V8? I don't think so!

-Uwe-

 

[Uwe]

@Gogo -- we don't need or want two separate threads about this problem, so they've been merged.

-Uwe-

 

[Gogo]

I believe I have solved the issue of non communication between the TCM and ECM. After removing the TCM I used a solution of water and baking soda to clean the contacts in the harness that plugs into the TCM. I also made a special little tool for cleaning deep inside the contacts.

Ran a scan and no P1624/18032 code so it appears things are working. A few days will tell the tale.

Not involved with this issue but I did change the range selector switch on the side of the tranny. I went thru the instructions and it looked to be quite the time consuming procedure. To remove the switch you need about 3/8 inch more clearance. The material on the transmission/engine mount is quite thin in that area. 1/8 inch. I used a reciprocating saw and remove a small triangular piece of material. Removal of the small piece gave enough room to remove the switch without going through the process of removing the mount.

 

[Jef]

I would suggest using contact cleaner.... but the concern I would have.. rot on the terminals means it was wet for a while, and most likely water has been pulled into the harness itself. Maybe a few inches in.... maybe more. ???

 

[Gogo]

I had tried contact cleaner but to no avail. The contacts are coper with i suspect a silver coating. There was the usual green corrosion you see on copper. I made a small scrapper from 14 ga solid core wire and ran it into the contacts multiple times in order to remove the green corrosion.

Rod

 

[Gogo]

Were the terminals at the TCM tarnished, rotted, crusty, or pickle falvored? If a harness has been wet for a while, moisture will get pulled into the harness (capillary effect). This can cause wiring to rot on the inside. I'm 99% sure the TCM is awake and talking to other control module, so power/ground for example are in place (good enough.... currently), but other wiring, such as the K-line and maybe a sensor are rotted.... thus no comm and TCM is in a fail mode.

Hands on the the TCM again and ohm test the K-line as noted in post #2.

After cleaning all the terminals the ecm and tcm are communicating as i do not get any codes or indication showing lack of communication. No CEL. Itried scanning the tcm but it comes up with no communication. It appears to be cold related. If the car is warmed up for 10 minutes and the key cycled it starts and shows the gear indicated in 2 or 3 attempts. Temperature is inn the minus 10 C range. Even on cold start up the engine runs smooth and is a normal cold start with the exception of the lack of gear indication.