B5.5 Passat Estate Boot Lock popping open when locking car

[Preece]

Hello,

I am having a problem with the tailgate on my B5.5 Passat Estate. Currently, when the lock button is pressed on the key fob all four doors lock, however the tailgate pops open. (The tailgate doesn't open fully, just onto the latch)

To counter-act this, the actuator in the tailgate has been unplugged, because if it is left plugged in, it pops open immediately. The only way to enter the boot is to insert the key into the boot lock and operate it manually.

It is as if the boot is being pressed on the key fob.

To note, the dash displays that the tailgate is open correctly

I have changed the drivers door locking module as i have heard this could contributing to the problem, however the problem still persists.

Any advice is very greatly appreciated.

[Rob69]

I sounds like it could be a comfort or convenience module fault, is the footwell carpet wet?, the module is under the passenger footwell carpet and prone to getting wet and wiring problems. if you get a full VCDS scan it might show up as a fault code.

[Preece]

Thank you for the reply.

The P/O of the car has had the CCM replaced, however i would not rule this out as a possibility. I was given the original CCM as "evidence" that it had been replaced, but research suggests that the loom could also be corroded. I have felt around the surface of the footwell carpet, however it does appear to be dry. I will investigate further.

Fortunately i have been able to borrow a friends Genuine Rosstech VCDS and have full scans. Thinking this was a coding issue, i changed the code "00065" to "00258" as suggested and shown below.

Before i changed the drivers door locking module, these are the fault codes that i had;



Address 46: Central Conv. Labels: 1C0-959-799.lbl
Control Module Part Number: 1C0 959 799 B
Component and/or Version: BZ Komfortgerát HLO 0003
Software Coding: 00065
Work Shop Code: WSC 01271
Additional Info: 1C2959802 6U Tõrsteuer.FS KLO 0004
Additional Info: 1C2959801 0M Tõrsteuer.BF KLO 0002
VCID: 36633F9C1291D8F660-4B00
3 Faults Found:


01362 - Close Switch for Tailgate/Trunk (F124)
29-10 - Short to Ground - Intermittent
01134 - Alarm Horn (H12)
49-00 - No Communications
00928 - Locking Module for Central Locking; Front Driver Side (F220)
27-10 - Implausible Signal - Intermittent

And after the drivers locking module was replaced;

Address 46: Central Conv. Labels: 1C0-959-799.lbl
Part No: 1C0 959 799 B
Component: BZ Komfortgerát HLO 0003
Coding: 00258
Shop #: WSC 01271
VCID: 36633F9C1291D8F660-4B00


Subsystem 1 - Part No: 1C2959802
Component: 6U Tõrsteuer.FS KLO 0004


Subsystem 2 - Part No: 1C2959801
Component: 0M Tõrsteuer.BF KLO 0002


Subsystem 3 - Part No: 1C0959811
Component: 0M Tõrsteuer.HL KLO 0002


Subsystem 4 - Part No: 1C0959812
Component: 0M Tõrsteuer.HR KLO 0002


2 Faults Found:
01134 - Alarm Horn (H12)
49-00 - No Communications
00931 - Locking Module for Central Locking; Rear Right (F223)
27-10 - Implausible Signal - Intermittent

It's almost as if the fault has been pushed into another area of the car, as the rear right central locking module fault code was not present before.

I can account for the alarm horn as the P/O has unplugged it.

I was hoping it could be a simple fix, but i'm beginning to think otherwise :1zhelp:

Once again, any help or advice is appreciated!

[Rob69]

Check the wiring at the CCM as this seems to be prone to corrosion and breaks

[Preece]

Is it possible that the CCM that has been fitted is incorrect, or that the CCM is coded incorrectly?

I am aware there are various CCM’s and they can differ, despite having the same part number stamped on the exterior CCM casing.

I am struggling to find the relevant information online to allow me to cross reference the CCM coding, can anyone help me with this?

Thanks!

[Preece]

I have checked the wiring loom and it is in great condition, not corroded and as dry as a bone.

12v is being sent to the rear tailgate lock to open it when the LOCK button is pressed on the remote or when the boot is closed with the car being locked.

Does anybody have any idea what could be causing this?

Thank you for any help

[Preece]

desperate bump :1zhelp:

[Dacruz]

Hi Pearce, have you fix the problem?
Because I am having the same exact problem.
Thanks

[VAG-Abound]

Has it just started after being OK before? Anything changed recently?

[Dacruz]

The car recently has soffer water damage from an inundation.
The water only reach the carpet, all the wires correded was fixed and the comfort module was replaced and cooded by a used one, and the carpet dried.
All the windows, lights and locks work.

The problems happening is the trunk opening when locking the car, battery drain, and the module looks like is reseting when I turn on the engine because it turns on all the lights inside, tries to unlock the doors, the locking of the windows and doors stops working, and after turning off the car to lock the doors the remote doesn't work.

On the Vag-Com the only thing I noticed was when unlocking the car rear left door keeps showing that is locked but it unlocks and when the module seems to reset the door then appears unlock, the trunk opens and the communication goes from 2 wires to 1 wire.

All sensors of the door is open or closed are working.

These are the errors that appear on vag-com:

VCDS
Self-Diagnosis
Log Tuesday,30,May,2023,14:32:37:00009
Page 1
VIN: License Plate:
Address 46: Central Conv. Labels: 1C0-959-799.lbl
Part No: 1C0 959 799 B
Component: 4Q Komfortgerát HLO 0003
Coding: 00259
Shop #: WSC 31480
VCID: 366393DF1247743D68-4B18

Subsystem 1 - Part No: 1C1959801
Component: 10 Tõrsteuer.FS KLO 0002

Subsystem 2 - Part No: 1C1959802
Component: 10 Tõrsteuer.BF KLO 0002

Subsystem 3 - Part No: 1C0959811
Component: 10 Tõrsteuer.HL KLO 0002

Subsystem 4 - Part No: 1C0959812
Component: 10 Tõrsteuer.HR KLO 0002

3 Faults Found:
01362 - Close Switch for Tailgate/Trunk (F124)
29-10 - Short to Ground - Intermittent
01336 - Company Data Bus for Comfort System
80-00 - Single-Wire Operation
00930 - Locking Module for Central Locking; Rear Left (F222)
27-10 - Implausible Signal - Intermittent

Sorry the English.
Thanks

[VAG-Abound]

Do you have a VCDS scan from before and after the problems / replacements? It might some a small but important change in part numbers, software levels, coding, etc.

And what model is the car, and its year of build / registration? Maybe same as thread title, but maybe not...

[Dacruz]

No I only have the scan after the module replacement, because it was in a shop and they never could fix this issues.

The car Volkswagen Passat Estate 1.9TDI B5.5 from 2001.

Thanks

[VAG-Abound]

Looks like the correct part number. The errors on shorts, intermittent connections look unhealthy though. I'd try to eliminate those...

[Dacruz]

Ok, thanks.
When I have a little time time gone a check the connections.

[Korji]

Hi all,

Has anyone found a fix for this issue?
I’m having same fault codes.
Yes, CCM was changed few times but returned to original. But same issue with the tailgate trunk occurs.

Have changed many parts in trunk locking system just to fix this issue, but nothing hasn’t helped.

Strange thing that even trunk open button (above license plate - changed also to new one) doesn’t react. Trunk is only possible to open by the key.

It would be nice if someone has solution how to fix it 🙏

Passat B5.5 Estate 1.9TDI 2002

[Crasher]

Have you checked the wiring in the roof to flap conduit?

[Korji]

Yes I checked and wires are quite in good shape. But because of rubber it’s hard to see full harness. But on the angles they are still like new

[Crasher]

You need to detach the boot and give them a good tug...:p

[Korji]

You need to detach the boot and give them a good tug...:p

Yeah i figured. But at the moment I don’t have opportunities for it because of snow everywhere. Garage is also occupied.
For addition, VCDS can’t connect to 09 Central lock channel also. And fault <01336 - Company Data Bus for Comfort System 80-00 Single Wire Operation> keeps appearing. So it’s 100 precent means that I got dead wire and not a module?