Touran: Faulty Electronics & Bus System Issues

Hello,
"For some time now, the electronics in my Touran have been malfunctioning. It started with the central locking system not working properly, or only functioning partially. Sometimes the doors wouldn't close, or not all the doors would open or close. Then, the turn signals would occasionally fail or simply get stuck, with the lights staying on continuously. During driving, the climate control would sometimes turn off and then come back on after about 10-15 seconds. Or the radio would briefly switch off. Sometimes the ESP warning light would illuminate, but it would go off again after a restart. The GRA light started blinking irregularly. Also, the dashboard lighting would sometimes turn on and then off after a few seconds, without the headlights illuminating."
Sometimes, after a while, the whole thing would just disappear.
My once had its error memory read, and it showed an error for all sorts of systems related to the single-wire bus of the comfort system. The technician said it could be due to the control unit (for the comfort systems), or perhaps just a corroded connector there, or a defect somewhere in the cable of the bus system. But finding the exact cause could require disassembling the entire car.
Okay, here's my question: What options do I have for working on this myself? Where is the control unit for the comfort systems located? As far as I know, only 3 single-wire bus systems are connected to it (e.g., interior monitoring), and the unit itself is connected to the CAN bus.
Does anyone have any ideas?

Thank you!

It sounds like the component is waterlogged. Since water tends to flow downwards, I would start looking for it in the footwell on the driver's side. However, I'm not entirely sure.

Okay. And where exactly is the control unit located? I seem to remember it being somewhere in the passenger footwell, on the side of the center console. Is that still correct?

A friend of mine had the second battery fail.
The most bizarre errors occurred, including instances where the suspension system would attempt to recalibrate itself.

The Comfort STG is located on the right side, at the front of the central channel.

Disassembly: Remove the glove compartment, disconnect the cables from the comfort control unit (CCU), and unscrew the CCU.

The Comfort CAN bus connects the following modules: the four door control units, the parking assist system, the air conditioning system, the auxiliary heater, special control units, the trailer control unit, the vehicle network control unit, and the diagnostic interface. (Each module is included if it is installed in your vehicle.)

The Comfort-Line bus is equipped with an alarm horn, tilt sensor, and ultrasonic interior sensor.

Your errors don't seem to be related to the single-wire (LIN) bus, but rather to problems on the comfort-CAN bus. If even a single device on the comfort-CAN malfunctions, it can cause these kinds of issues. Therefore, it will be very difficult to pinpoint the exact cause.

We need a complete error memory log from all control units, including the exact wording of the error messages. Anything else will likely be guesswork. Please find someone with VAG-COM / VCDS and post the results here.

Regards,
Guste.

2. Battery?
Does the Touran have a second battery?

oops yes shit


...I meant, of course, the Touareq :-/

Let's forget about it *hehe.

"So, lately I've been getting the "rear door open" warning more often, even though the door is closed. And sometimes I can't even open the door. Where is the control unit for the rear door opening located? Maybe I'll take a look at that."

Regarding the issue: The hose for the rear windshield washer had a crack, and washer fluid leaked into the comfort control module located behind the glove compartment. That was the cause of all the problems.

Excellent resolution .

The same problem occurred in my Touran. The hose for the rear window washer fluid has torn behind the dashboard... so... I removed the dashboard, repaired the hose, and checked all the cables there. Then, I replaced the comfort control module with one that has the same part number. Unfortunately... there was no improvement in the symptoms. The error description matches 100% with what the original poster described. So, somehow, the entire electronics inside the car are malfunctioning .

Does anyone else have any ideas about what it could be?! Help!

Based on my experience from back then, I can only tell you that you should carefully examine the connectors, especially the contacts inside. The water ingress caused corrosion on the contacts in my case, and I had to replace several cables and use jumper wires because the pins no longer made a clean connection. If the antenna cable for the central locking system is affected, it is crucial to use the correct cable and the exact length of the cable.
When replacing the control unit, the coding also needs to be checked (e.g., using VCDS).

The dashboard doesn't actually need to be completely removed for this job. Just take out the glove compartment, and you'll have good access. However, it also depends on where the corrugated hose is damaged. In my case, I had to replace a larger section completely.

Thank you for the quick response and the tips. I will probably have to take a closer look at the 4 connector plugs. In my case, the corrugated hose was torn right behind the ventilation nozzles - so really directly in the middle behind the dashboard, and there was actually no other way to get to it.

I haven't recoded the comfort control module yet. However, I assumed that even without proper coding, at least some errors would disappear. What color is the antenna cable for the remote control? I'll leave that alone for now.

The cable is black, but after a few centimeters, you'll notice that it's a different type of cable (a coaxial cable).

First, check the encoding, then I would look into it further.