Complete electronics failure??

[pcplum]

Hello folks
Been having problems lately with a mysterious drain on car battery (a brand new Bosch battery).
Had battery and alternator tested and both absolutely fine. Nothing being left on and whenever I check the battery sporadically with an amp-clamp there is no recorded current draw.
Went out today and again, completely flat, having started fine yesterday.
Can't even jump car as now dash lights flicking/clicking on/off. Is this ecu or the immobiliser kicking in? Problem is I can't seem to unset anti-theft system...
All doors currently unlocked and I can only lock the front two using the emergency key.
Going spare with this one as I currently have best part of 2 tonnes of scrap metal on drive. PLEASE HELP!!
Car is a 2006 Passat estate 2.0tdi (140)
Thanks in advance.

[RichardSEL]

Have you changed your radio at all?

Is there any spark when you disconnect the negative battery terminal clamp? While you're there, remove it and
connect a charger -- a trickle overnight one will do. I'm skeptical about these "amp clamps" and the other testers Halfords put
on to pronounce your battery "bad" or otherwise.

What is the battery terminal volts with everything off (but negative connected)
And with negative disconnected?
And with starter motor trying?
What colour are your headlights when switched on? And after a minute?

Try connecting the battery negative terminal by black jump cable to the engine block itself. Often the electrical bond goes bad which shows up especially in high current conditions when operating starter motor

Let us know how you get on?

[pcplum]

Have you changed your radio at all?

Is there any spark when you disconnect the negative battery terminal clamp? While you're there, remove it and
connect a charger -- a trickle overnight one will do. I'm skeptical about these "amp clamps" and the other testers Halfords put
on to pronounce your battery "bad" or otherwise.

What is the battery terminal volts with everything off (but negative connected)
And with negative disconnected?
And with starter motor trying?
What colour are your headlights when switched on? And after a minute?

Try connecting the battery negative terminal by black jump cable to the engine block itself. Often the electrical bond goes bad which shows up especially in high current conditions when operating starter motor

Let us know how you get on?

Yes, changed radio a few months ago and it does tie-in timing wise. I noticed inside the car the sound of a relay clicking once every 10 seconds or so. Sounded like it was coming from behind centre blower vents...
Just picked up a battery charger so will get that going and let you know how I get on.
Any ideas on the clicking and flashing dashlights? I'm thinking immobiliser, but not sure. Also, how do I disengage it if neither key is doing anything? Should i be able to reset with a fully recharged battery?

[turboextreme]

The erratic lights and clicking is due to the lack of power to wake the BSI / body control module up this is why everything goes erratic.
When you fitted your radio did you install a wiring harness adaptor as if you didn't you will cause short circuits to the BSI as the genuine radio uses a active aerial amplifier feed and adaptive speed volume control these need to be disabled when fitting after market units or the BSI won't go into hibernation/ sleep mode when car is locked.

[pcplum]

The erratic lights and clicking is due to the lack of power to wake the BSI / body control module up this is why everything goes erratic.
When you fitted your radio did you install a wiring harness adaptor as if you didn't you will cause short circuits to the BSI as the genuine radio uses a active aerial amplifier feed and adaptive speed volume control these need to be disabled when fitting after market units or the BSI won't go into hibernation/ sleep mode when car is locked.

Ah, that would seem to make a lot of sense. Any idea on what harness adapter I need?
Many thanks

[RichardSEL]

Ah, that would seem to make a lot of sense. Any idea on what harness adapter I need?
Many thanks

Depends on what head unit you bought? There's a range of Quadlock adapters and CANbus/steering wheel adapters at Connects2 site

If you upgraded an OEM headunit, or to some of the more recent Android headunits, then you'll need an updated CANbus module too.
A '56MY B6 would have a "C" version. To change out you'll need someone with VCDS to do the fresh module's coding

[pcplum]

It's an Android head unit. It came with a quadlock connector, and canbus stuff all seems to be working (doors open, odometer, temp, battery voltage info, reversing lines that move with steering wheel etc). I don't have steering wheel controls.

This is the head unit:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItemVersion&item=231545081647&view=all&tid=1378954044013

So, given the above, do you recommend a replacement canbus module, and any idea on costs, fitted?

You'll have to forgive my utter ignorance with all this - auto electronics are definitely NOT my forte!!

Please keep the help coming! Happy new year.

[pcplum]

Looking at some other threads/forums, it seems other folk have had a battery drain issue when changing stereo units and an updated canbus module gateway is the answer. So, the golden question is, if I upgrade to the 'Q' module, will my issues be solved? A quick scan of posts suggests dealer would charge £250-300 to replace and reprogram new module?? Also seen plenty of warnings to stay away from the Chinese-made ones on eBay...?

[RichardSEL]

The latest Android headunits don't completely switch off (like the up-to-date OEM headunits RNS510 etc)
The "Q" version is the latest but you don't need to go that far for an OEM one. Version "F" or later should
be alright

Re-coding should be done by VCDS. As you're buying second hand it might still have latent coding in it from
the doner car. So your original coding from your "C" version will have to be noted down, then coded into
your "F" version or greater when it's changed out.

I did a FAQ in this forum many years back. But anyways, the module's behind your heater control panel, mounted
upside down held in place by a bar with two bolts either side.

Disconnect battery and loosen the bolts and your old module will slip out sufficiently for you to lift the plug's latch and unplug. Reverse procedure with replacement. Replace your heater control panel (if you only have the four position knob Climatic system be careful the Bowden cable doesn't slip out -- it will have to go back in the same position as removed)
If you have two window Climatronic then it's just that panel out and remove the three plugs at the back and then reach in.

Re-connect battery and then do the coding. Tewksbury's a tad too far for me, so you might need someone local to do the coding:
Here's the URL:
https://www.google.com/maps/d/viewer?mid=zwQHurSsCMz8.kMTwqF0PoXwc&msa=0&ll=56.231139%2C-2.779541&spn=3.493691%2C10.821533&iwloc=0004c505cfcb6158e0447

Or it's a VW indie. They shouldn't mind fitting a "F" or later second hand part.

Search for 3C0 907 530 <suffix letter>

Hope that helps. Keep us updated?

[pcplum]

Many thanks for this - it's very much appreciated. I will get on the hunt for a replacement module.
Will keep you updated.
Thanks again.

[pcplum]

Apologies for tardiness in replying. So, ended up buying a new canbus gateway from VW (£180) and a local auto-electrician did the fit & reprogramme (£160). Expensive, but it now all works and there's no latent drain on the battery post-switch off.
Thanks again for all your help and advice.
Matt