[Clearancediver]

There is actually a small charge that "blows" and separates the cable from the battery terminal connection. This is supposed to happen in a bad collision to eliminate the possibility of gas tank contents igniting from electrical "sparks" etc….. there is a separate small wire (SRS system) that joins the BST at the BAT/battery cable that initiates the charge.

That is why wiggling/pushing the battery cable back into the battery terminal can reestablish (sp?) the connection/power.

Get INPA/INSTAD software to read the codes that have been generated.

As part of your "repair" I would disconnect and clean the connectors under drivers /passenger seats with electrical cleaner.. clear codes if you didn't do this with the battery disconnected. SRS wiring passes through both those connectors. Also clean the afore mentioned cable connector that is located some 12-24" back from where it connects to the BST. That connection can get dirty and cause a fault due to increased resistance in the wire. I eventually cut this connector out and replaced it when it faulted once to many times and I couldn't clean/get within the correct resistance value. Both mentioned software programs allow you to test and read the actual resistance of the wire.

Apparently you can get and splice in used BST end of cable…. but they are/have been difficult to obtain according to posts on this issue over the past number of years. Given that the battery is located over the gas tank in the Z…. I'm in agreement with the BMW engineers decision to have the car built with a BST installed.

Have fun….