Weird issue with E87

[Bilaal E]

Hope everyones doing good and could possibly share some knowledge here

Car: E87 120d auto

So the car has went in for a gearbox overhaul. While it was there, I asked the mech to give it a check to see if there is any other issues. He picked up the alternator wasn’t charging correctly and some diodes needed to be changed. Also I needed a new battery. Anyway, he went ahead and did that and one the first evening the car lost electric power to the cluster, gauges drop and interior lights switch off and started throwing warning lights. All random and different. The car with the red car on lift also comes on. While this errors show. None of the electrics have power. Also the car wont lock with the remote. When the car is in this state, I can hear various electric components almost trying to switch on. Sometimes the wipers would also run, with the ignition completely off. And that drains the battery.

The car was run on a few diagnostic systems with no errors picking up. ECU, FRM are all fine. Auto elect checked the battery and alternator saying it is charging. Sorry for the long paragraphs but I am lost as to what the problem may be?!

Anyone with advise will be highly appreciated

Thank you

 

[Danny2]

Scan the car to check for faults cause something is not happy.

I have seen the issue with the cluster randomly dropping and that was the alternator on that car. Also with regards to the Doors not locking and wipers going ... do the windows work?
Normally a sign that the FRM is destroyed.

 

[Bilaal E]

It was scanned with the Autoboss and lauch and one other one, not sure of the name lol
Windows work perfectly.

 

[Solo Man]

Yes, sounds like the stuff that went on with my ex 2005 120d when i bought it. Lights on the dash would come on, power loss, speedo or rev counter would drop to zero. Stompie had the same issue with his 120d and the answer was a new alternator. Check the charge rate of the existing alternator for a few minutes and it should momentarily drop from 14,2 to about 12,2 for a second or two and then go back up to 14,2. That is a good indication that the alternator is the problem. I fitted a new aftermarket alternator (was not happy to but had already paid the guy and when i collected the alternator it was pirate) but worked fine for the time i had the car. Never had the problem again.

 

[Bilaal E]

*SOLVED*
So just for future reference, if anyone comes across the same issue..
Turns out the problem was the votage regulator. The guys who repaired the altenrator before did a cut and join job on the brushes to make it fit. These were giving problems, replaced the entire unit and issues are fixed

 

[Gordvisr]

glad you got sorted, blow's my mind when people try and modify stuff like these, especially on electronic side of a car, it can end badly.