MINI Cooper Forum banner

R53 Electrical issues, BCM fault or other?

7K views 3 replies 2 participants last post by  Restyle 
#1 ·
Hi all,

I purchased around 14 months ago and have just this week finally got round to looking at it and putting it back on the road.

I bought the car with what was suspected as BCM failure as none of the electrics worked. fitted the 'New' battery that came with the car and it would start and drive but no electrics worked (wipers, indicators, windows brake lights etc etc) Head lights and rear lights are constantly on regardless what position it is in on the stalk.

I went and bought another brand new battery to try as this one was now flat when i went out to have a fiddle, fitted it and the car started up and all electrics worked fine windows worked wipers worked lights turned on and off via the stalk as they should. started the car a few times yesterday and seemed fine.

Went to start the car today and now back to how it was when i bought it nothing works again.

could this be a voltage issue somewhere along the way, something like a resistor that isn't resetting itself and allowing full voltage to flow through after starting the car?


Open to any suggestions as to what could cause this.

Thank you.
 
See less See more
#2 ·
....Went to start the car today and now back to how it was when i bought it nothing works again...
Hi Scotty,
Do you mean that the Battery is totally flat again so nothing works, or that it starts ok but lights etc are stuck on?
If the former, then that indicates that something is drawing current when the ignitions off - thus flattening the battery. On my first MINI it was the radio that was faulty and could drain the battery overnight - but it could be anything from a faulty Alternator diode to boot light remaining on.
Need Multimeter to check current drain on full battery whilst removing fuses & see which one stops drain. - then investigate/ change that fused item individually.

If the latter, then it may be water leak causing faults in the BCM - fit bcm watercover if it doesnt have one , repair leak & dry unit out.
 
#3 ·
not sure if something is draining battery, i put a brand new one on to test and worked fine, tried again a few hours later and stopped working, charged it back up to full tried again and still not working.

BCM is totally dry too so thats why im confused so much. cheers
 
#4 ·
not sure if something is draining battery, i put a brand new one on to test and worked fine, tried again a few hours later and stopped working, charged it back up to full tried again and still not working...
Lets get this correct - Do you mean that after charging for the second time that nothing worked from the moment it was put on, or that things worked for a short while before stopping?
If the latter, then that definitely sounds like symptoms of battery drain to me.
Have you got a multimeter - you really need one for this type of fault - great autoranging one here for £20 >> UNI-T UT202A Auto-Ranging AC DC Digital Multimeter Handheld Clamp Meter Test Tool: Amazon.co.uk: DIY & Tools
Very useful for this type of fault as it can simply clamp around one of the main battery leads, and tell you what any drain current is - if any.

Im also thinking about a possible bad joint on one of the battery leads going to or from the main 250Amp fuse in battery compartment {if its an MCS} - see also this thread >> Battery Safety Terminal Self Destruct - North American Motoring
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top