Golf V CAN bus problems + drawing battery

Hi ppl,
I need help with this car, car is Golf V 1.4 2005. The problem looks very complicated but i will try to break down what is going on.

The car was involved in left side crash, year and half ago. The repair was done which involved welding too, changing the doors and so on, don't know what exactly. The car was "repaired" and it was fine til last 5-6 months. Left airbags which went off were never replaced but rather disabled IC warning lamp or hole system, i don't know.

The car came to me couple of days ago because of problems with battery going low and this is happening occasionally for the last 5-6 months, i started with diagnosis and i felt deep down the rabbit hole.

Car indeed drains the battery but not every time or whole of the time, it is intermitent i would say. During diagnosis i found that car doesn't go to sleep on low speed can bus, CCCM (Comfort Central Control Module) is clicking inner relay and trying to do something and it draws around 400-700 mA. Then i went even deeper and found that on Convinience Can Bus at Can L voltage is arround battery voltage (short to plus) and then i continue with unpining and unpluging modules. I unplugged cccm and there was no change on bus, then i unpinned the can lines and there was no change on the bus and on the side of cccm there was also battery voltage at can l coming out, i put everything back. Then i continued further on the other side and now i ended up with Gateway module unplugged, 6 fuses out and the bus is at around 5V. If i unplug the BCM too the bus goes to 1.5V. When i plug back in the gateway and bcm bus goes up to 8V. If i disconnect the battery completely f.exmp plus pole the voltage on the bus slowly decay to zero, it takes a while to get to zero. There is a good communication on the bus lines, and when communication stops the can l goes again to high voltage either battery or 8-9v depending where you are taking measurment. I found out that at Infotainment Can Bus there is also 11V at can l.

So my question is what could cause this strange behaviour? Bad ground doesn't sound likely. Multiple failed modules doesn't sound likely either.
Does high voltage on can l line can cause modules to stay on and not go to sleep? Because low speed can is fault tolerant and can work on one wire.
Plan is to disconnect all of the modules from Convenient Can Bus, there is 6 or 7 modules and to check the bus wires itself. I will try to power gateway and cccm on the bench and scope communication pins. After that i am stuck, don't know how to procceed with this one.

I did full scan and it didn't help too much, there is 01330 fault code pointing to cccm. There are other codes but irrelevant to me, imo.

Not even a single answer, that's strange. Maybe you guys was confused with so much text, i believe there are ppl who can offer some answers.
Anyway forget about the car and the problems described in previous post, that is way behind us.

I wanna ask something else or rather in different way.

If i am working on can network (low speed - crossed pattern of waveform) and if i have one wire shorted to plus and i unpin from the plug can l and can h from module and i check on the module side on the pins coming from module and there is 12V, is it safe to say that module is gone? Is there any case where this should be normal??

Other example, three wire alternator, B+, PWM i guess, because it is coming straight from ecu and other wire from ecu through heater control module On pwm wire there is constant 11v plugged or unplugged from alternator. Is it enough to condemn the ecu?? My thought procces is that there is possible to have short to plus from alternator to ecu somewhere in wiring harness but still wouldn't be there some sort of communication and fluctuation on the waveform instead of fixed 11V?? Is it possible to have some sort of strategy on ecu which says cut that circuit off because there is short to plus and thats why you can't see any coms?? But short to plus stays since it is in harness. Otherwise it should be able to pull that signal to ground.
If there is 11V on the ecu side with that wire unpinned is that enough to say module is toast.

When car is running there is 13V on the wire. Generally 1V less from normal voltage being either running or stopped.

Again lot of question but i hope someone will be able to answer on some at least.

During diagnosis i found that car doesn't go to sleep on low speed can bus

How long did you wait for modules to go to sleep. It can take up to an hour for some modules to time out. Any activity on the network will reset the timer.

CCCM (Comfort Central Control Module) is clicking inner relay and trying to do something and it draws around 400-700 mA.

What was your battery voltage at this point. Low battery voltage, itself, can cause relays to click wildly. I would recommend using a battery maintainer while waiting for time-out.

If i am working on can network (low speed - crossed pattern of waveform) and if i have one wire shorted to plus

Can you post a waveform? With a test-light connected to battery (-), will the short to plus light the test-light? Or, does it pull it down?

and i unpin from the plug can l and can h from module and i check on the module side on the pins coming from module and there is 12V, is it safe to say that module is gone? Is there any case where this should be normal??

I, personally, would not condemn a module based on this test. This may be a bias voltage that is pulled down to network voltage (2.5v), by the network resistance? I, really, don't know. :dry: The results of the test-light on the "short to plus" may give the answer to this.

You are right, thanks for your help. I can't remember voltage levels at the time.

No, i didn't test with a test lamp i should have do that but i checked just with a scope.
If is biased voltage where does it come from?What is the point to have it on the comm lines?
In case if is there solid 12v i guess you can condemn the module then.

What about questions about alternator, anyone?