Alhambra/7M - KI occasionally fails

Hi,

My Seat Alhambra (identical to the Sharan 7M) from 2008 with a 2.0 TDI (103/140 hp) engine is currently at the repair shop.
The problem is that the power supply for the instrument panel, ventilation system, radio, etc., occasionally fails during driving. The motor continues to run, and there are no errors in the KI (as expected, since there is no power).

I have now pulled out all the relays behind the fuse box, but the KI is still always under voltage.
In my opinion, there should still be some kind of central relay responsible for the power supply. Does anyone here know where I can find this?

In general, not every consumer is supplied via terminal 15 through a relay, but the ignition switch already handles a portion of the load currents.
However, the heating fan is usually connected to the "X-contact" of the relay, which is switched off during organ playing to start the motor. D.h. if you pull all the relays, the ventilation shouldn't work - unless the Alhambra is wired differently.

To further isolate the problem, you will likely need an SLP.

vwSchrauber wrote:

The problem is that the power supply for the instrument panel, ventilation, radio, etc., occasionally fails during driving.

Does only clip 15 (ignition) not work for these consumers, i.e., can the radio be turned on again? Or does the entire KL 30 (extended duration) requirement disappear for these devices?

ulf wrote:

In general, not every consumer is supplied via a relay at terminal 15, but the ignition switch already switches a portion of the load currents.

I was just about to disagree with you that there's still something directly connected to the ignition switch on a 2008 vehicle. (On the Passat 3C, nothing has been directly switched by the ignition switch since mid-2005). But the Sharan is technically exactly the same as our Galaxy BJ2006 and therefore actually from 2000. (It's incredible how long VAG has managed with this model).

The ventilation system receives power directly from the ignition switch via fuse 3.
Radio also.
Combination instrument receives power (+), DIRECTLY from the ignition switch, WITHOUT a fuse.

D.h. ZAS should be okay. For testing, you can check fuse 3-5 to see if there is still voltage present in the event of a fault. These are directly supplied by the ignition switch (black wire, 4mm²).

Greetings
Guste

You won't believe this: yesterday, I disconnected the battery while the engine was running, and guess what - exactly the symptoms described in the documentation appeared during all the voltage fluctuations (window regulators).

I've had the mechanic install a new battery, and so far (90km), it's running perfectly.

Then you were really lucky that the increased voltage (lack of battery reserve) didn't damage your hearing.

Quote:

Then you were really lucky that the increased voltage (lack of battery buffer) didn't affect your hearing.

The times have long passed. For example, at John Deere, various service manuals point out that it is possible to operate a system without a battery, provided that the regulator is equipped with a "overvoltage protection" device.

Possible... However, with my brother-in-law, several STG modules failed due to a loose connection in the B+ terminal. The reason is unknown, but VW did offer compensation.

Honestly, I wasn't very comfortable when disconnecting it, but thanks to TFL and seat heating, the voltage never exceeded ~14.5V even during fluctuations (measured with an oscilloscope to see even short outliers).

Still running without any problems.
The dead battery (about 2 years old) is now being cleaned, polished with silicone spray, new protective caps are being put on, and it is "randomly" positioned "in a way that makes it less likely to be stolen" - so it definitely won't fall into the wrong hands

...and then to be thrown into the woods by some kind of scoundrel...

matthiasTDI96 wrote:

super...then to be thrown into the woods by some kind of scoundrel...

More likely in a salvage yard where there's still something for it, based on weight, which East German collectors know how to estimate very well

I need to buy a new battery soon. The price for an old battery was, as far as I know, 10 EUR. So, it would certainly not be wise to throw them into the forest.

I seem to recall something around 30 cents per kilogram for used batteries.

Quote:

super...then to be thrown into the woods by some kind of scoundrel...

Grant the thief a long and expensive debugging process

The battery deposit is applicable. W. at 7.50 EUR.