> > 1. Appears to be a "mechanical failure not electrical" says the reputable
> > local BMW dealership
[quoted text clipped - 7 lines]
> these which would leave 4th, neutral and reverse needed for the limp home
> mode still operating normally - this is a symptom of electronics failure.
> > Failure of the various clutch packs and brake bands similarly effects
> > the operation of some gears, but as I said before I can't think of the
> > failure of one of these which would leave 4th, neutral and reverse
> > needed for the limp home mode still operating normally - this is a
> > symptom of electronics failure.
> Is it anything like if the computer detects anything wrong it just
> shuts down? I.e. a small fault might occur but that triggers the
> computer to shut down the whole system?
If say your alternator dies, and you continue driving, one of the first
symptoms you'll notice as the battery volts drop is the gearbox goes into
limp home mode. It could be the solenoids need a full '12 volts' to
operate efficiently, so this is why it shuts down earlier than other
electronics on the car.
> Dealers will hook the car up to the diagnostic system and then say
> "computer says no". That is if they know how to do that properly or
> indeed want to do it properly. Did they offer to buy your car from you
> at a knock down price?!
The computer is anything but infallible - and that's assuming the dealer
told the truth about the findings.
> Like Dave says BMW don't make the boxes and don't support their repair
> (or maintenance in most cases)
Mine also farms out AC work and body repairs. Weird, really.
> It's like buying a PC at PC World and expecting them to be able to fix a
> power supply fault.
In that case it's simpler to just fit a new supply as the labour cost to
fix it is likely to exceed it.
Not so with an auto - although it might be at main dealer labour rates if
a full recon is needed.
I've not had a modern ZF apart yet, but I'm told the valve chest and
internal electronics are accessible without removing the box.

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*A backward poet writes inverse.*
Dave Plowman dave@davenoise.co.uk London SW
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