Desperate need of help Audi 8E Brake light fault

   #1  

GUNT

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Hi All

new to this forum , we have never been caught out anything like this but as Audi have no record of this and i cannot find any thing and nothing makes sense .

ok so we had brake light switch fault 00526 quick check with multi meter , so satisfied it was faulty ordered new one its a superseded part , fitted new part fault still on the system , checked with multi meter and the switch is working correctly this lead to further investigation , this is a two sided switch with 4 wires before anybody asks yes in every system abs/engine ecu, live data can be viewed and only one side is at fault , this is the red/brown + feed red/black signal wire
so i have 12+ in the wires that should with one closed side sending 12+ back to abs until brake is pressed , the red/black wire should be 0v until brake pressed and then should be 12+ signal to abs ecu
so once the new switch was fine i check the wires further, and i have 7v on the red/black signal return wire , chased all the wires for a short to the abs ecu , were right hand drive over here , so in the pass side foot well i opened the wire connection plug , with the plug open i checked from here back to the brake switch was checked and had in or around 6.56v in it so i was sure i had a wire issue , checked the other side to the abs ecu with the connection remade and pin red/black removed we had 8v so satisfied also had a wire issue on this side too
when the circuit is remade the voltage drops to 7v
after serious tracing i found what you see below which is wired in to the red/brown deliberately putting reduced voltage into the red/black and with the pin removed from the abs ecu i find the ecu is in fact sending out 8v on a signal pin which should accept 0 or 12v
this is not a one off i have found the same in another a4 same year and i have now tested 3 abs ecu's from one with and with out the capacitor wired in to the brake light switch
id say the extra faults in abs are due to pluggin and out ecu

Code:
Thursday,09,March,2017,21:13:15:34799
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x86
VCDS Version: 17.1.3.0
Data version: 20170220 DS267.3
www.Ross-Tech.com

Dealer/Shop Name: GUNT TUNING

VIN: WAUZZZ8E45A076501   License Plate: 


Chassis Type: 8E (8E - Audi A4/S4/RS4 B6/B7 (2001 > 2008))
Scan: 01 02 03 08 09 0F 11 15 16 17 18 25 36 37 45 46 55 56 57 65
          67 69 75 76 77
 
VIN: WAUZZZ8E45A076501   Mileage: 270630km-168161miles
-------------------------------------------------------------------------------
Address 01: Engine        Labels: 038-906-019-AVF.lbl
   Part No: 038 906 019 LJ
   Component: 1,9l R4 EDC 0000SG  5934  
   Coding: 00002
   Shop #: WSC 06335  
   VCID: 6AD0D60316F8061157-4B32
   WAUZZZ8E45A076501     AUZ6Z0D0303555

1 Fault Found:
16955 - Brake Switch (F) 
            P0571 - 35-00 - Implausible Signal
Readiness: 0 0 1 1 1 

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 8E0-614-517.lbl
   Part No: 8E0 614 517 
   Component: ABS/ESP front       4529  
   Coding: 00000
   Shop #: WSC 00000  
   VCID: 65CAA53FFFE629697A-515A

3 Faults Found:
01044 - Control Module Incorrectly Coded 
            35-00 -  - 
00526 - Brake Light Switch (F) 
            36-00 - Open Circuit
00778 - Steering Angle Sensor (G85) 
            66-10 - Not Matched - Intermittent

-------------------------------------------------------------------------------
Address 08: Auto HVAC        Labels: 8E0-820-043.lbl
   Part No: 8E0 820 043 AC
   Component:   A4 Klimaautomat   1424  
   Coding: 00000
   Shop #: WSC 06335  
   VCID: 62C0BE23EEC85E519F-5178

3 Faults Found:
00819 - High Pressure Sensor (G65) 
            30-10 - Open or Short to Plus - Intermittent
00819 - High Pressure Sensor (G65) 
            07-10 - Signal too Low - Intermittent
01330 - Central Control Module for Central Convenience (J393) 
            49-10 - No Communications - Intermittent

-------------------------------------------------------------------------------
Address 09: Cent. Elect.        Labels: 8E0-907-279-8E2.lbl
   Part No: 8E0 907 279 C
   Component: int. Lastmodul  RDW 0606  
   Coding: 00001
   Shop #: WSC 06335  
   VCID: 32600E63FEA88ED12F-4B32

3 Faults Found:
01330 - Central Control Module for Central Convenience (J393) 
            49-10 - No Communications - Intermittent
01326 - Control Module for Multi-Function Steering Wheel (J453) 
            49-10 - No Communications - Intermittent
01312 - Powertrain Data Bus 
            79-10 - Please Check Fault Codes - Intermittent

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 8E0-959-655-84.lbl
   Part No: 8E0 959 655 J
   Component: Airbag 8.4EP        1002  
   Coding: 0011602
   Shop #: WSC 06335 000 00000
   VCID: 3E782A536AF05AB1DB-515A

4 Faults Found:
01228 - Airbag Cut-Off Switch for Passenger Side (E224) 
            010 - Open or Short to Plus - MIL ON
01228 - Airbag Cut-Off Switch for Passenger Side (E224) 
            010 - Open or Short to Plus - MIL ON
01739 - Crash Sensor for Front Airbag; Pass. Side (G284) 
            011 - Open Circuit - Intermittent
01218 - Side Airbag Igniter; Passenger Side (N200) 
            001 - Upper Limit Exceeded - MIL ON

-------------------------------------------------------------------------------
Address 16: Steering wheel        Labels: 8E0-953-549.lbl
   Part No: 8E0 953 549 S
   Component: Lenksáulenmodul     0611  
   Coding: 01001
   Shop #: WSC 06335  
   VCID: 438E5BA751123759B4-4B18

2 Faults Found:
01330 - Central Control Module for Central Convenience (J393) 
            49-10 - No Communications - Intermittent
01332 - Door Control Module; Passenger Side (J387) 
            49-10 - No Communications - Intermittent

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 8E0-920-9xx-8E2.lbl
   Part No: 8E0 920 950 M
   Component: KOMBI+WEGFAHRS. RB4 D42  
   Coding: 00401
   Shop #: WSC 00186  
   VCID: 336E0B6701B287D924-5178
   WAUZZZ8E45A076501     AUZ6Z0D0303555

No fault code found.

-------------------------------------------------------------------------------
Address 45: Inter. Monitor        Labels: 8E0-951-177.lbl
   Part No: 8E0 951 177 
   Component: Innenraumueberw.   0704  
   Coding: 00001
   Shop #: WSC 00000  
   VCID: 6BDED30719021F192C-513C

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv.        Labels: 8E0-959-433-MAX.clb
   Part No: 8E0 959 433 BC
   Component: Komfortgerát T3B    1512  
   Coding: 06859
   Shop #: WSC
 
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   #2  

GUNT

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Kae5rTF.jpg
 
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Uwe

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Moving to Car Repair Support.

-Uwe-
 
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GUNT

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thanks for the help
 
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Jack@European_Parts

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Hello OP and welcome to the VCDS forum.

WTF is that in that wiring.........?
Are you looking to start a fire?

Please correct the FOD and install the correct parts for lights and wiring as per the Etka & RTFB using WD in repair manual.


That's not OEM............ correct it or go buy some marshmallows!


TUV what what what !
 
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GUNT

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sorry to say it is OE and i have now found it in 3 out of 8 ive checked in this year , every one identical and identical in every mannor heat shrink wiring and distance its placed from the switch .
this is my point there is no repair manual to follow because none show this or a flow chart to test
i had a bit of time yesterday , and removed more of the dash to get room , so i got brave and cut the red/black wire ecu side of the resistor/coil imput , tested and it does not match the one i cut from another car but the 8v is still in the loom , remove pin from abs ecu still there remove pin from engine ecu and its gone but the engine and abs ecu are bot placing 8v in the signal return red/black from the brake light switch , so what happened did something fry both ecu's and the resister , ive used 3 different abs ecu and all the same but the engine ecu was still implace at the time if i replace bith who is to say what will happen do i need to wire back in this set up in the pic :banghead:
 
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GUNT

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6.5 yrs in Audi VW ALL normal procedures followed as i said they have nothing documented on it and it would be some one with experience of it who i'd say will be the only one able to shed light , thanks for the imput but I've 20 yrs at nothing but problems and never seen anything especially something undocumented
 
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Jack@European_Parts

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Noise suppression circuit.

Question is: Where exactly? And why?

-Uwe-

Yeah poor deployment of a Ferrite stick inverted.



Op are you absolutely sure all fuses are OK?

I suspect there is a blown one............or an open bay.
 
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GUNT

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as said before all powers are correct there for fuses fine but i have checked all either way , this is not a can wire its a simple switch return wire 0 or 12v , but still why has both ecu's decided to send out 8v on this wire that the resistor is wired in to at the same time .
 
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GUNT

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Power and earths checked at pin of each ecu all correct
 
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