Complete loss of comfort features and more in the VW EOS

Hello everyone,

I've been having a problem with my VW EOS since this morning. It's a 2007 model (model year 2008), 2.0 TDI.

After noticing a somewhat weak battery, I connected it to the charger (electronically controlled) last night and locked the vehicle. This morning, I disconnected the battery charger (which indicated it was fully charged) and tried to unlock the vehicle with the remote, but there was no response. The driver's door opened with the key, but nothing else happened. The passenger door and trunk are closed. The vehicle started without any problems, but immediately displayed the message "AFS, please refer to the manual." The power windows, turn signals, windshield wipers, and central locking system are all inoperative. Lights are on, engine is running, DSG is engaged, brake lights are on, radio is on, so driving would probably be possible (without using the turn signals).

Okay, then turn off the ignition, the left window goes down a bit and stops there; you can't open it any further. I probably adjusted the end stop incorrectly.
When the ignition is turned on, the engine fan runs continuously at its maximum speed!

Battery disconnected for 5 hours, tried again, same error.
All fuses checked, all are okay.

I checked with VCDS and almost everything came up red!

Don't be surprised that the voltage is so low; I only ran the logging after many tests (with and without the charger connected). The problem persists even with a good battery voltage.

I suspect it might be the comfort control module, but...
The problem is, I can't open the passenger door, and therefore I can't remove the glove compartment, which is where the control unit is located... Help!

Can someone get a sense of the overall situation?
How do I open the passenger door?

Thank you for your help, tips, and ideas.

Best regards, Mirco.

Hi,

First, revive the battery, and then clear all errors using a CAN message (broadcast).

Turn off the ignition, wait a moment, and then test. Then, please check what's happening and which errors reappear when the onboard voltage is okay (perform an Autoscan).

If, after the charging process is complete and the 10-minute diagnostic check, the onboard voltage drops below 12.0V, you should consider purchasing a new battery.

Best regards, Rainer.

Hello Rainer,

Thanks for the tip. I've ordered a new battery; I think the current one is probably not in the best condition anymore. However, even when I connect the old, charged battery to a battery charger, it doesn't restore the functions, and I then have approximately 13.4V at the battery.

Please read my post again and do exactly what it says...

Your car scan showing errors from "yesterday" (undervoltage) for a condition "today" (no undervoltage) is indeed for the Lokus.

Solved!

After I installed a new battery, the error, as expected, was still present. I had to replace the battery anyway because it was no longer working properly.

After receiving a tip from a member of another forum about a similar issue, my research focused on the SmartTOP roof module.

The module was accessible via USB, but it was not recognized correctly.

Okay, I disassembled the trunk and removed the SmartTOP module, disconnected the T-connector cable and reconnected the wires directly...

TATATA Comfort Bus is back online!

All errors were cleared with VCDS, a test drive was performed, and there are still no errors in the control units.

I connected the SmartTOP to my computer once, and when you tap on it, it's sometimes accessible and sometimes not, so it definitely has a problem.


So, if absolutely nothing else works in a comfortable bus and a roof module is installed, check that first!

Best regards, Mirco.

Hello,

Thank you for the feedback! Since the mentioned module is a retrofit control unit and does not appear to be integrated into the vehicle's diagnostic system, nothing related to it would have appeared in a diagnostic scan.

However, it doesn't make much sense to analyze a complete system scan (error scan) when it contains a large number of errors that are caused by circumstances that are long past. For example, Undervoltage in control units, which is when the strangest things tend to happen.

Therefore, after saving the Autoscan and addressing the specific error (in this case, undervoltage in the vehicle's electrical system) always clear all errors and see what reappears!
In your case, the problem would have been CAN communication errors, and if you had mentioned that something extra was connected to the CAN bus due to the modification, we could have investigated that possibility further.

Quote:

I once connected the SmartTOP to my PC, and when you tap on it, it's sometimes accessible and sometimes not, so it definitely has a defect.

A short circuit or loose connection is possible; a visual inspection of the circuit board is recommended.

Best regards, Rainer.