BMW X3 - Multiple problems - kenlum

My November, 2007 (51) X3 SE Diesel Automatic, owned since 6 months old has done 36.000 miles and has been serviced as per manufacturers instructions.

The following warning lights came on at the same time today:

4x4, ABS, Brake system, Tyre pressure, Air bag; in addition, the speedometer and cruise control do not work and the mileage remaining from the current fuel tank contents moves erratically.

They have quoted me£1.500 for diagnostic work and a new DSC Control unit (which will take 3 - 5 days to come from Germany. They say that further work may well be required once the new unit is fitted & they check the other faults.

They are unable to provide a courtesy car and we are 175 mile away from our home in Scotland

Can anybody help?

BMW X3 - Multiple problems - gfewster

Multiple electronic failure like that points to a lack of electrical supply to several components, possibly due to a bad connection or blown fuse/relay (best case) or a duff ECU (worst case).

Readings on any instrument fluctuating wildly indicates inconsistent voltage or current being received, possibly pointing to an alternator fault.

Who 'quoted'? A BMW dealer? What did they do before coming up with that 'solution'?

Diagnosing a duff ECU without doing any proper diagnostic work looks like they're seeing pound signs rather than a problem that needs fixing.

If it did turn out to be a duff ECU, I'd be onto BMW UK and telling them that failure of such an expensive component after 3-4 years isn't acceptable on a supposedly premium brand (warranty or not), and asking for a substantial contribution to the costs.

BMW X3 - Multiple problems - Collos25

All the symptoms you describe are those of a faild abs ecu these are available for 350ukp including fitting in the UK .Here in Germany BMW have admited there is a problem with this unit and give a substanstial discount on the price if you want to use them.

BMW X3 - Multiple problems - SteveLee
Additional to the above, if the car still has an alternator (some modern cars don't!), try unplugging it then take the car for a drive, if the speedo etc problems disappear then your problem is the rectifier in the alternator failing creating electrical "noise" which is confusing the various computers, a replacement alternator + a reset of the DTC codes will be all that's required.
 

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