E70 not starting

[ezimoto]

Hi guys.
New here but hope someone can help.
I have an 07 3.0d E70 which will not start. Press button and there is small click then nothing. Thought starter however on testing the trigger wire it gets power for a couple of seconds when pressing button then it loses it.
Borrowed ista d from friend which shows no communication with VTG module EPB module and also EHC module.
These appear to be on different bus circuits so not sure how they relate to each other.
Anyone have any bright ideas please, ista is unfamiliar to me unfortunately though I am familiar with similar systems.
Thanks in advance

[X5Sport]

Is the battery OK?  Should be at least 12.2V (measured under the bonnet) with the car asleep.  Fully charged the battery should be 12.6V.  Anything less and the system may not crank.  Below 11.6V means a bad battery.  Given you have power going to the trigger, it points at either insufficient current/voltage to pull the solenoid or possible a jammed solenoid/or perhaps bad starter.

What happens if you add a jumper pack/second battery?  Does it then crank?

[ezimoto]

Thanks for reply, should have put more info, sorry.
Car is on a 13.5v power supply (and has new battery which has been coded as that was first thought).
The power to the trigger only lasts a few seconds (monitored with a test light) then is no longer present, almost as if the car is sensing it should not be started and kills the trigger feed.
Thanks again, any further thoughts most welcome!

[X5Sport]

If the trigger pulse is at the starter but nothing happens that still makes me feel the solenoid may be stuck.  Used to happen on old cars and a whack with a spanner usually cleared it.  The system probably only uses a few seconds to prevent overheating and to stop the starter current killing the battery.  If you have a voltmeter see what happens when you trigger the starter.  A current clamp will tell you what the starter is actually drawing.

Is the solenoid actually moving?  It just could be a broken contact inside too, so the iron slug moves but nothing happens  >:(

Charging voltage should be 14.4V if you have an AGM battery and 13.8V for a 'wet' battery.

A number of people on here have had issues with new AGM batteries requiring replacement very soon after purchase.  I've just had that happen to me with the battery being fine when measured off load suddenly dropping to 5.9V on load!  AGM cells seem to be problematic, especially if they have ever gone flat for any reason - including before you owned it!

[ezimoto]

Wet battery fitted so think my 13.5v should be enough and tried jumping from van for luck!
Like the idea of some kind of protection killing the trigger feed. Will try to rig something up off a separate power supply directly to the starter with the cars wiring removed to do a bit more testing, not helped by the usual wonderful BMW starter access....
Will report back with progress tomorrow, thanks very much again for your help.

[X5Sport]

I know what you mean by access!  To change the starter on a LHD E46 you need to remove the prop shaft and loads of stuff on the engine in order to lower the gearbox just to get a 2 bolts!  Not quite that bad in the RHD version, but still an absolute pain!!

[kjb1]

Check your earth points, also especially check the power point used for jump starting.  Get a spanner on that and pull it up as much as possible.  It feeds power to starter from the battery, grease it aswell! I had very similar issues to you, put a new starter in, same problem, turned out it was loose fitting on the power terminal mentioned, only a few mm of travel was enough to fix it.


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[mrmjn]

Mine has done this it doesn’t happen if I use it every day but after a few it didn’t start with same issues I tried the spare key and starts on the button every time I’m guessing the rechargeable battery in the key not holding a charge!

Worth a try?