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5 Series Beamer

Diary of a Second Hand 15 year old Beamer (Maintenance - Battery Drain included...,
BMW E39 520i year 2000 Engine 1995cc)
M Series.

Workshop/Diary - Electrics

 

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Contents Page

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Workshop

Possible cause of Battery Drain 
Note; Safety - Before commencing with Electrical Work, Disconnect Battery)

Battery Cable

Another option: Battery lead (seen on eBay £40 seconds, so not sure if they are the ones taken off cars with the problem, another case of being careful).
You can buy a splice kit for the battery end. Through research, I have discovered there is a shut-off resister or fuse mechanism that shuts down the battery, (battery end) linked to the airbags, once airbags are deployed the resister on the battery terminal blows and it renders the electrics dead, this may accidently trigger without bag deployment, so one to be aware of.
Again the slice kits can be bought from a salvage yards or from eBay, full leads are priced, no more than £40 (Nov 2014) negotiate as some can be less as £20, so it is worth looking around. Splice kits can be around the £5 and £10.

Circuit Breaker on Battery Cable

fig.  Full lead can be purchached or a spliced lead can be reattached to the original main loom

BST Overview

Actuation Circuit

Gas Discharge Tube

Spring Tabs

B+ Cable

Quick Check: Grab the Cable and Push Towards the Terminal

If It Moves, BST Has Been Triggered!

1. Minor Impacts may trigger BST Igniter capsule, car can still start and runs, but has B+ codes and Airbag Codes, Power Codes, BST Codes.

Tampered B+ Cable Contact Point

Igniter
Capsule

Tampered End of B+Cable is Forced From  It's Seat

1.

2.

Spring Prevents Return or Resetting of Contact Point

Resistor

See Video :  Battery Cable Splicing Process in Resources

Note: On replacement of cable you will be required to reset the airbag light using OBD II tool.