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Firstly, something I noticed before buying the car is that for some unknown reason, a PO had decided to paint the foremost speaker grills black…
Looks bloody awful. Not only that, but they hadn’t bothered to take them out of the doors so there were bits of black paint on the corners of the recesses, and in the inside edge of the door pockets. And to top it all off, they’d used a thick black paint, probably Hammerite, and used A BRUSH to apply it!!! This has resulted in thick globs of paint effectively blocking vast areas of the grilles. What on earth goes through these people’s minds?!?
I took both door cards off and removed all grilles. I split them down, used a paint stripper on the metal grilles (this stuff took HOURS to get off) and cleaned up the plastic backing pieces. I discarded the foam (it was ruined by the paint). I used magnolia coloured radiator spray paint on the now bare metal grilles, cut fresh 3mm acoustic foam to size and reassembled them. Now, they’re back to how they should look…
Much better.
After that, a new battery management module 3D0915181D was delivered, and I was able to fit this temporarily above the carefully insulated system battery:
Upon starting and allowing the engine to idle, my Bluetooth battery monitors reported that both batteries were now charging normally - this had never happened before:
I cleared all codes via VCDS, and now have no faults in the 71 Battery Charger address. Hopefully this means no more going out to the car in the morning and not having any audio or interior electronics for the first 10minutes of the drive, then having them randomly come back and go off again.
The new (used) module is actually from a Phaeton and has the same part number apart from the last letter (D instead of C). I’m assuming there was a revision as this unit has a manufacture date of ‘09, but seems to work fine.
I bought 2x Ancel BM200 units - you can see one stuck to the side of my system battery in the photo above. Very cheap (less than £20 each) and very easy to set up and use.
I bought 2x Ancel BM200 units - you can see one stuck to the side of my system battery in the photo above. Very cheap (less than £20 each) and very easy to set up and use.
Good news is the batteries are charging nicely. So that’s sorted.
Bad news is the audio and seats are still cutting out. Been scouring the WDs to see if the two systems are linked but other than the CAN bus, can’t find anything definitive.
I’ll be pulling up the passenger side carpet again tomorrow to check the thermal fuses as two of those four are for the seats.
@scrinja working on this car has left my hands shredded!
So started at the systems battery and checked all the fuses, starting with the bigguns, and found no continuity on fuse F3, 80A. When I undid the nuts and took it off, I found a load of white oxidisation on the bus bar terminal:
Gave it a whizz over with a dremel grinding bit, same with the fuse terminals, put it back on and since then, no more electrical dropouts! Looks like that corrosion was allowing only a small amount of current to pass through the fuse, but would register faults and shut down the larger consumers (ie seats and amplifier) on the circuit when they tried to draw higher currents. Such a relief!
Do you know I think corrosion is a huge fault creator on these cars. Good diagnosis and a bit of observations if you can get to the areas are probably the way forward.
What age is your car Dan? I would like to do the battery monitoring thing, is that an addition or a replacement part?
So the battery monitors are aftermarket, they cost about £20 each and just attach to your battery terminals. They continuously log the State of Charge, voltage and temperature, and when your phone is in Bluetooth range, they transmit that data to the app allowing you to view it as graphs. Very handy.
Unless you mean the Battery Management Module, that’s an original part which is bolted to the inner wing behind the Systems battery. Mine was quite literally fried and would not allow the Starter battery to charge. I replaced that with a used one from a Phaeton, and all was well again.
Very cool. Do the monitors just run off the battery they are connected to or do they have their own key fob style battery? Could you provide a link to an example as Id like to buy some. Much appreciated.
