BMW X5 E70 4.8 M Sport

[Andy Collings]

Hi, I have a weird thing happening with my X5 E70 4.8. Twice now I have had warning messages come up for Transmission fault and 4x4 system fault and the idrive screen says proceed with caution but do not switch off engine as it will not restart. The first time it happened I had been driving about 100 miles and the second time about 10. First time I carried on my journey to home but car had limited power and transmission wasn't quite right at pulling away. Googled the problem and forums said ignore the car and switch off engine and restart it. Did this and all was ok for 3 months. Second time same message and warnings, turned off engine and it wouldn't start, had to have a jump. Also clock, date goes off and service sign comes up. Once restarted all ok again. Anyone got any idea what is causing it ? First time was 1 week after brand new battery fit, second time 2 weeks after battery negative lead replaced. Related ? Alternator seems fine! Any input or idea's be welcome. My email address is apcollings@hotmail.co.uk please reply on post and to this, thanks.

Andy

Edited October 5, 2019 by Andy Collings
email address

[Greydog]

Morning Andy

X5's are sensitive beasts that throw hissy fits when they don't get the power they crave. First the replacement battery should be 12v 95ah 800 cca minimum also I can't recall at which year the battery has to be registered to the vehicle. As they also changed the negative lead I would check that its tight (probably is now) but also check the main earth point in the boot is clean and tight (I had all sorts of issues traced it to the mounting bolt at the earth block removed cleaned it re-tightened it no issues since) Battery voltage should be 12.8v ignition off 14.4v engine running if that's all OK and the alternator checks out then the original faults were probably related to the earth lead causing charging/power issues.

Dave