Help! Break lights not working when the car if off

[Carbon]

Hey everyone, I recently got a 2012 Golf TDI and have some electrical issues.

I am going to dive in to the wiring diagram and start troubleshooting but I could really use some help or pointers on what to look for. I listed the issues I found and the car history below.

1- The break lights do not come on when the car is off.
2- The lights work when the axillary is on or when the car is running
3- The driver side break light turns on once I unlock or lock the alarm then turns off after a few minutes. The same light will also turn on if I open the door.
4- driver lock switch not working

The car was hit on the driver side and both doors were fixed or replaced.

 

[DrGERTol]

@Carbon -- All exterior lighting, include the brake lights, are controlled & powered directly by the CECM/BCM J519 mounted above the driver side footwell in the instrument panel. You should scan the car with a proper VAG diagnostic tool and look for fault codes in Address 09; generic OBDII scanners are not sufficient for this diagnostic. --g

 

[oilhammer]

OBD works. Need to start there.

Couple things:

brake lights do NOT work with the key OFF, that's normal.

the underhood fuse box is a common source of lots of electrical problems on that model, including but not limited to exterior lighting.

 

[Carbon]

@Carbon -- All exterior lighting, include the brake lights, are controlled & powered directly by the CECM/BCM J519 mounted above the driver side footwell in the instrument panel. You should scan the car with a proper VAG diagnostic tool and look for fault codes in Address 09; generic OBDII scanners are not sufficient for this diagnostic. --g

@ DrGERTol thanks for the tip. Ill try to get my hands on a VAG diag tool. or find someone here in Houston that might have one.

 

[Carbon]

OBD works. Need to start there.

Couple things:

brake lights do NOT work with the key OFF, that's normal.

the underhood fuse box is a common source of lots of electrical problems on that model, including but not limited to exterior lighting.

@oilhammer that is good to know about the light not working with key off. ill also take a look at the fuse panel.

 

[Carbon]

Ill keep everyone updated on what I find as I go.

 

[wonneber]

OBD works. Need to start there.

Couple things:

brake lights do NOT work with the key OFF, that's normal.

the underhood fuse box is a common source of lots of electrical problems on that model, including but not limited to exterior lighting.

Is the "brake lights do NOT work with the key OFF" car specific?

 

[wonneber]

Is the "brake lights do NOT work with the key OFF" car specific?

I had to go out, turn my 2014 JSW around so I could see the break light reflection in a window.
Take the key out of the ignition, wait a minute and step on the brake pedal.
They worked.
Did I misunderstand your message?

 

[Carbon]

OBD works. Need to start there.

Couple things:

brake lights do NOT work with the key OFF, that's normal.

the underhood fuse box is a common source of lots of electrical problems on that model, including but not limited to exterior lighting.

@Carbon -- All exterior lighting, include the brake lights, are controlled & powered directly by the CECM/BCM J519 mounted above the driver side footwell in the instrument panel. You should scan the car with a proper VAG diagnostic tool and look for fault codes in Address 09; generic OBDII scanners are not sufficient for this diagnostic. --g

Just want to make sure I'm understanding this right. the taillights do not have a constant hot that bypasses the control module in case the car breaks down?

I checked with a scanner that is VW compatible and it has no brake codes. I also checked the wiring and the break light is getting a constant hot as soon as the car is unlocked.

 

[DrGERTol]

@Carbon -- The BCM/J519 is supplied Terminal 30 (unswitched) power from fuse panel B in the engine bay, which allows it to operate the central locking and lighting systems, among other things, with the ignition in the OFF position.
Might be useful to look at live data for the BCM/J519 for incorrect input signals. Also, is the BCM original ? BCM long coding might be an issue here ? --g

 

[Carbon]

@Carbon -- The BCM/J519 is supplied Terminal 30 (unswitched) power from fuse panel B in the engine bay, which allows it to operate the central locking and lighting systems, among other things, with the ignition in the OFF position.
Might be useful to look at live data for the BCM/J519 for incorrect input signals. Also, is the BCM original ? BCM long coding might be an issue here ? --g

Thank you, I will have to take a look at the live data. as far as I am aware the BCM/J519 is the original one. What do you mean by BCM long coding is that like corrupted firmware on it?

 

[Wilkins]

If it’s a replacement BCM and the coding for byte18 is not for your vehicle the lights may do weird things. Doubt that is your problem though. Also VW hides the byte 18 code so you can’t see what it is. It will show 00 IIRC.

More likely is if doors were replaced someone ‘modified’ a wiring harness.

 

[Carbon]

If it’s a replacement BCM and the coding for byte18 is not for your vehicle the lights may do weird things. Doubt that is your problem though. Also VW hides the byte 18 code so you can’t see what it is. It will show 00 IIRC.

More likely is if doors were replaced someone ‘modified’ a wiring harness.

Ok. thanks for the info I will take a look and update my findings.

 

[Carbon]

@Carbon -- The BCM/J519 is supplied Terminal 30 (unswitched) power from fuse panel B in the engine bay, which allows it to operate the central locking and lighting systems, among other things, with the ignition in the OFF position.
Might be useful to look at live data for the BCM/J519 for incorrect input signals. Also, is the BCM original ? BCM long coding might be an issue here ? --g

If it’s a replacement BCM and the coding for byte18 is not for your vehicle the lights may do weird things. Doubt that is your problem though. Also VW hides the byte 18 code so you can’t see what it is. It will show 00 IIRC.

More likely is if doors were replaced someone ‘modified’ a wiring harness.

I noticed that the center elect module didnt have any byte code for 13 is that normal?
I read the car again and didn't find any codes for the control module only for navigation, airbag and passenger door. I placed the codes below.

01-Engine -- Status: OK 0000
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
15-Airbags -- Status: Malfunction 0010
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: OK 0000
25-Immobilizer -- Status: OK 0000
2B-Steer. Col. Lock -- Status: OK 0000
2E-Media Player 3 -- Status: OK 0000
37-Navigation -- Status: Malfunction 0010
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
47-Sound System -- Status: OK 0000
52-Door Elect, Pass. -- Status: Malfunction 0010
55-Headlight Range -- Status: OK 0000
56-Radio -- Status: OK 0000
62-Door, Rear Left -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000

Address 52: Door Elect, Pass. Labels:. 1K0-959-702-MIN3.clb
Part No SW: 5K0 959 702 H HW: 5K0 959 702 H
Component: Tuer-SG 009 2105
Coding: 0008368
Shop #: WSC 00000 000 00000
VCID: 382929533E5D76EAD73-806C
1 Fault Found:
01044 - Control Module Incorrectly Coded
005 - No or Incorrect Basic Setting / Adaptation


Address 37: Navigation (J794) Labels:| 1K0-035-27x-37.clb
Part No SW: 1K0 035 274 B HW: 1K0 035 274 B
Component: RNS315-NAR H35 0265
Serial number: VWZAZ2M4218457
Coding: 04050001010005000000100A
Shop #: WSC 01357 011 00200
ASAM Dataset: EV_RNS315NARV2UDS A01004
ROD: EV_RNS315NARV2UDS.rod
VCID: 2313EE3F9B5B0532121-8076
Data carrier:
Subsystem 1 - Part No: 3AA 919 866 B
Component: NAR_V8N 0066

Address 15: Airbags (J234) Labels:| 5K0-959-655.clb
Part No SW: 5K0 959 655 H HW: 5K0 959 655 H
Component: AirbagVW10G 013 0724
Serial number: 003GVRA225X0 Dataset Number: 5K0003v__B_ 0068
Coding: 00003131
Shop #: WSC 01357 011 00200
ASAM Dataset: EV_AirbaVW10SMEVW360 A01014
ROD: EV_AirbaVW10SMEVW360.rod
VCID: 3FDB424F17F341D2169-806A
Seat occupied recognition:
Subsystem 1 - Part No SW: 5K0 959 339 B HW: 5K0 959 339 B
Component: BF-Gewichtss. 006 0001
Serial number: ---0000R--00002T5200
Crash sensor for side airbag: driver side:
Subsystem 2 - Part No SW: 5K0 959 354 HW: 5K0 959 354
Component: S.Sens.Fahr.V H01 ----
Serial number: 3572MSME2E4A206DZZZ1
Front Passenger's Side Airbag Crash Sensor:
Subsystem 3 - Part No SW: 5K0 959 354 HW: 5K0 959 354
Component: S.Sens.Beif.V H01 ----
Serial number: 3582MSME3C65206DZZZ+
Rear Side Airbag Crash Sensor (on driver's side):
Component: S.Sens.Fahr.H --- ----
Serial number: 3512QSME7C121109ZZZO
Passenger side rear thorax airbag crash sensor:
Component: S.Sens.Beif.H --- ----
Serial number: 3522QSME5E4D0F09ZZZ9
Crash sensor for front airbag: driver side:
Component: F.Sens.Fahr --- ----
Serial number: 35527SME7C65712BZZZR
Crash sensor for front airbag: front passenger side:
Component: F.Sens.Beif --- ----
Serial number: 35627SME0B1D712BZZZN
1 Fault Found:
9438747 - Igniter for Seat Belt Tensioner; Driver's Side
B1006 1B [10001001] - Resistance Too High
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 1
Mileage: 201828 km
Date: 2023.10.20
Time: 06:41:05