Fan Runs Until Battery Dies - VW Touran 2.0 TDI

Hello everyone,

I've been following this forum for a while now, and I hope someone can offer me some advice regarding my current "problem."

"On our Touran 2.0 TDI 110kW SCR (VIN: 0603 BWR), the radiator fan has been turning on shortly after the engine is turned off, especially when the outside temperature is around 14°C or lower. It runs for about 1-2 minutes and then turns off for approximately 1 minute. This cycle repeats itself about 2-3 times (I haven't counted exactly). Then, it stays on continuously until the battery is drained."

The first time this happened was last weekend. Then nothing happened for a week, and I eventually forgot to disconnect the battery… which worked perfectly fine until this morning. This morning, however, it was very cold with high humidity, just like last week when we were in Holland by the sea and we parked the car overnight.

Today, I took it for a short test drive and logged the coolant and oil temperatures, as well as some other values. Nothing unusual appeared during that time. Unfortunately, I couldn't find any relevant data that would indicate anything about the radiator fan control. Also, I noticed that the fan turns off immediately when you turn on the ignition!

Thank you and best regards.

Florian.

Often, the problem lies with the fan control unit itself.

My sister's car had a similar problem recently. Unfortunately, the only solution was to replace the blower motor (which includes the control unit).

I strongly suspect that the previous speaker is correct.

The fan in your vehicle likely only has a thick power wire and a constant positive connection, as well as a thin signal wire (LIN bus). There may also be a thin ignition wire present.
That means the fan only receives commands to turn on and off via the LIN bus. For testing purposes, you could try connecting only the two thick wires to the fan and see if the problem still occurs without the LIN connection. That would make it clear whether the issue is related to the LIN bus or something else.

Alternatively: Disconnect the fan and measure the quiescent current of the rest of the vehicle. If something is powering the fan, the quiescent current will be significantly higher. If the quiescent current remains normal, then the problem is also with the fan.

Regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

Thank you for your feedback...

Based on my research so far, I've come to a similar conclusion. It seems that the control unit, either within or directly connected to the fan, is responsible.

Overall, the behavior is very strange... When you physically open the driver's door (not just unlocking it remotely), the fan turns off; when you close the door, it turns back on after about 10-15 seconds. This can be repeated indefinitely. The same applies to turning the ignition on and off.

Since there's a used car warranty on the vehicle, the dealership should take care of it. I won't be doing much myself other than a diagnostic check without any repairs. Unfortunately, they have very few available appointments... and my girlfriend wants to go back to Holland for two or three nights with our daughter on Wednesday. So, for now, it will probably remain with the battery disconnection workaround. And of course, my A3 is still at the body shop... typical Murphy's Law! :/

Sure, here's the translation:

"Thank you and best regards."

Florian.

Hello,
What was the cause?
I'm having the same problem with my father's Tiguan right now...

Thank you in advance.

Hello,

"In our Touran, it was also a faulty relay. I had it fixed at the dealership... the cost, including battery check, was roughly €170 before tax."

Sure, here's the translation:

"Vg" is an abbreviation for "very good." It can be used to express approval or agreement.
Florian.

Hello.
Briefly put.
The relay in slot 5 on the relay carrier in the engine compartment was also defective.
The engine control unit's fault memory was read using VCDS, and it showed an error code indicating that "the main relay is opening too late."
Greetings.