Intermittent Traction Control Light and ABS Light

[Ronin]

I would scan the car with VCDS first and go from there. I've had both front abs sensors go and they didn't reduce performance or anything like that.

[strummagnet]

Originally Posted by Ronin

I would scan the car with VCDS first and go from there. I've had both front abs sensors go and they didn't reduce performance or anything like that.

Thinking now that the brakes were grabbing on the wheel that the sensor is reading wrong. Coming from the rear so off to the power wash tomorrow to get rid of the mud and crud and go from there.

Cant scan as my computer isnt with me.

[Ronin]

When abs works you feel the brake pedal vibrate and there is a distinct buzz of the abs pump, the brakes will never just randomly grab like when driving with adaptive cruise control etc.

My front abs sensors started to play up when going over bumps and the above is exactly what I would get. The fault was later narrowed down to the piece of ABS sensor which goes from the strut to the body, it simply got worn out after 20+ years.

If it is the sensors for you, i made a guide showing how to make them for around £30 instead of paying £399 for new ones.

[steamship]

A blast from the past. From what I remember at the time, I removed and cleaned all the ABS sensors, which didn't seem that bad, followed the suggestion by ainarssems of monitoring the measuring blocks and they were fine. I also replaced a MAF at some point, but don't remember if it was to do with the same issue.

If the lights came on and went off again, scanning for errors may not show up anything if you switch the engine off, as they clear themselves. Not sure about anyone else, but I've never plugged in the VCDS cable when the ignition was on or engine running, as worried it might cause damage.

Not sure if it's related and don't want to muddy the waters, but since you'll be plugging in VCDS, check out the brake switch measuring blocks in module 01-Engine, address 66. Untouched it should read 0000, a slight push with your finger should read 1010, and a little bit more pressure should read 1011. Only because you mentioned a 'reduction in power', and if the ECU thinks the brake switch has been depressed, it will reduce the power.

[Ronin]

One of the biggest advantages of VCDs is loggin live data while the engine is running and the car is moving.
You can even save it to a text file and plot a graph with excell, I did that when diagnosing my abs sensors.

[strummagnet]

I found a VAG guy in Hexham who scanned the car, no faults present. Car was covered in 'muck n bullets' so kindly power washed it down. Driven over 120 miles today and not a murmur, drove in its normal 'sublime' mode. Took it back for another scan and still nothing logged.

Im travelling back down south tomorrow (via the A8 Parts Store in Stockton) so will see what occurs. Hopefully nothing.

Thanks for all your input.

[strummagnet]

Well, found some time in break from work to scan the car using VCDS light. Now have some codes. One thing of note that there is a lot of intermittent codes popping up so thinking loose connections somewhere?

VCDS-Lite
Windows Based VAG/VAS Emulator
Version: Release 1.2
www.Ross-Tech.com
Workshop Code: 000 00000
Self-Diagnosis Log
Sunday, 26 March 2023, 15:19:45:59133
VIN Number: WAUZZZ4DX2N007670 License Plate: PL02FKF
Mileage: 174544 Repair Order:
Chassis Type: 4D - Audi A8 D2
Scan: 25,01,03,08,11,15,16,17,18,35,37,45,55,56,57,65,67 ,75,76,77,02
-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: Redir Fail!
Controller: 4D0 820 043 Q
Component: A8-Klimavollautomat D13
Coding: 00081
Shop #: WSC 02313
VCID: 2A276756C5E7
No fault code found.
-------------------------------------------------------------------------------
Address 15: Airbags Labels: 4D0-959-655-AI8.LBL
Controller: 4D0 959 655 T
Component: Airbag Front+Kopf 5001
Coding: 01417
Shop #: WSC 02335
VCID: 43F92AF2428D
1 Fault Found:
01219 - Rear Airbag Igniter; Driver Side (N201)
33-00 - Resistance too Low
-------------------------------------------------------------------------------
Address 17: Instruments Labels: 4D0-919-033-MYW.LBL
Controller: 4D0 919 035 BA
Component: KOMBI+WEGFAHRS.VDO D39
Coding: 00483
Shop #: WSC 02313
VCID: 66BFD366117F
WAUZZZ4DX2N007670 AUZ7Z0A1942430
No fault code found.
-------------------------------------------------------------------------------
VCDS-Lite
Self-Diagnosis Log
Sunday, 26 March 2023, 15:19:45:59133
Page 2
VIN Number: WAUZZZ4DX2N007670 License Plate: PL02FKF
Address 35: Centr. Locks Labels: 8D0-862-257.LBL
Controller: 8L0 862 257 P
Component: CV-Pump, Alarm, RC D17
Coding: 15178
Shop #: WSC 02313
VCID: 42F72FF65D97
3 Faults Found:
01370 - Alarm triggered by Interior Monitoring
35-00 - -
01369 - Alarm triggered by Hood Switch
35-00 - -
01134 - Alarm Horn (H12)
49-00 - No Communications
-------------------------------------------------------------------------------
Address 37: Navigation Labels: None
Controller: 4D0 035 192 M
Component: RNS 4.2 H06 BNO 0102
VCID: 2925985AC0E1
1 Fault Found:
00862 - Antenna for GPS Navigation (R50/R52)
44-00 - Short Circuit
-------------------------------------------------------------------------------
Address 45: Inter. Monitor Labels: None
Controller: 4D0 951 177 B
Component: Innenraumueberw. D06
Coding: 00001
Shop #: WSC 00000
VCID: 28239D5EDBEB
No fault code found.
-------------------------------------------------------------------------------
Address 55: Xenon Range Labels: 4Z7-907-357.LBL
Controller: 4Z7 907 357
Component: dynamische LWR D07
Coding: 00001
Shop #: WSC 00000
VCID: 047BE9EE0703
No fault code found.
-------------------------------------------------------------------------------
VCDS-Lite
Self-Diagnosis Log
Sunday, 26 March 2023, 15:19:45:59133
Page 3
VIN Number: WAUZZZ4DX2N007670 License Plate: PL02FKF
Address 56: Radio Labels: None
Controller: 4D0 035 192 M
Component: Radio BNO 0001
Coding: 00207
Shop #: WSC 00652
VCID: 2925985AC0E1
1 Fault Found:
00852 - Loudspeaker(s); Front
36-00 - Open Circuit
-------------------------------------------------------------------------------
Address 76: Park Assist Labels: 4D0-919-283.LBL
Controller: 4D0 919 283 PÆu
Component: arkingsystem A8 RDW D07
Coding: 01108
Shop #: WSC 00000
VCID: 7399BA3252AD
No fault code found.
-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01L-927-156.LBL
Controller: 4D0 927 156 EC
Component: AG5 01L 4.2l5V RdW 1010
Coding: 00101
Shop #: WSC 02313
VCID: 6EAFAB46398F
1 Fault Found:
18265 - Load Signal: Error Message from ECU
P1857 - 35-10 - - - Intermittent
End --------------------------------------------------------------------------------------------------


Also:

Control Module Part Number: 4D0 907 559 AA
Component and/or Version: 4.2L V8/5V G 0002
Software Coding: 10753
Work Shop Additional Info: WAU CZoZdZe4 WXS2NC0 0007060700 AUZ7Z0A1942430
6 Faults Found:
17931 - Crash Signal from Airbag Controller: Implausible Signal
P1523 - 35-00 - -
17981 - Left Engine Mount Solenoid Valve (N144): Open Circuit
P1573 - 35-10 - - - Intermittent
17834 - EVAP Purge Valve (N80): Open Circuit
P1426 - 35-10 - - - Intermittent
17985 - Right Engine Mount Solenoid Valve (N145): Open Circuit
P1577 - 35-10 - - - Intermittent
17841 - Secondary Air Pump Relay (J299): Open Circuit
P1433 - 35-10 - - - Intermittent
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-10 - - - Intermittent
Readiness: 0010 0001

I have managed to clear all intermittent codes.

[steamship]

Originally Posted by strummagnet

Address 15: Airbags Labels: 4D0-959-655-AI8.LBL
Controller: 4D0 959 655 T
Component: Airbag Front+Kopf 5001
Coding: 01417
Shop #: WSC 02335
VCID: 43F92AF2428D
1 Fault Found:
01219 - Rear Airbag Igniter; Driver Side (N201)
33-00 - Resistance too Low

Something worth trying is checking the connectors (below the bench seat) and apply some dielectric grease. Ensure you disconnect battery first, and afterwards try and clear code from within address 15.

Originally Posted by strummagnet

VCDS-Lite
Self-Diagnosis Log
Sunday, 26 March 2023, 15:19:45:59133
Page 2
VIN Number: WAUZZZ4DX2N007670 License Plate: PL02FKF
Address 35: Centr. Locks Labels: 8D0-862-257.LBL
Controller: 8L0 862 257 P
Component: CV-Pump, Alarm, RC D17
Coding: 15178
Shop #: WSC 02313
VCID: 42F72FF65D97
3 Faults Found:
01370 - Alarm triggered by Interior Monitoring
35-00 - -
01369 - Alarm triggered by Hood Switch
35-00 - -
01134 - Alarm Horn (H12)
49-00 - No Communications

The alarm horn one is pretty common in all the VAG cars as their internal batteries dies and/or corrode. Hood switch might be loose connection or not secured properly. I've had the interior monitoring one before, but I was having issues with the central locking not unlocking the car.

Originally Posted by strummagnet

17931 - Crash Signal from Airbag Controller: Implausible Signal
P1523 - 35-00 - -

This might be as a result of the error in address 15 above.

[MikkiJayne]

The crash signal implausible is a peculiarity of this car that I couldn't solve. I changed all the ecus which can interact with the crash signal, to no avail, checked the wiring - all fine, sometimes it'll clear and go away for a bit, sometimes it comes back straight away. Its most puzzling. It could be something to do with canbus identities, since this one had so many replacement parts. Its the one code I couldn't get to the bottom of, but doesn't appear to affect anything and doesn't give any warning lights.

The engine codes are likely a bad connection in the ECU box. Pop the lid, and pull each connector in turn and give them a spray of WD40 and then put them back. I'll have a look at the diagrams when I get a chance and see if they all go through the same connector, or have a common supply or ground.

Keep a close eye on the MAF error and load signal implausible in the TCU as that can have an impact on the gearbox, both shift quality and consequently longevity. If it has a common supply or ground with the other bits that are having issues then it could simply not be giving a signal at times, but if its actually failed and giving a duff load signal that needs sorting asap.

I think its not terrible to change the rear seat airbags if that code is persistent after fiddling with the connector. I have plenty of spare seats which can donate one.

[steamship]

Originally Posted by MikkiJayne

The crash signal implausible is a peculiarity of this car that I couldn't solve.

Sounds like the low brake pad warning light staying on even after replacing the pads which I had for ages.

I searched that 17931 error code and came across the following post - note the 'Special Notes'. With your understanding of these cars, does it sound like a feasible solution?

http://wiki.ross-tech.com/wiki/index...1/P1523/005411

I've also attached a section of the wiring diagram (p.25) from Current Flow Basic equipment From model year 2001.pdf showing the 'crash wire' (A125). E3 is the hazard warning switch.