BMW BST cable gone bad

[apbx3]

My 2004 Z4 3.0i airbag light came on and took it to my mechanic to reset but it wouldn't and he said the BST has gone bad , is their a repair kit for it. My old e46 330 ci had it done , the whole cable runs for $400 not include labor.

[Clearancediver]

Try cleaning the cable connector which powers the SRS system. It's the single red wire with connector that connects to the battery power terminal in the battery well in your trunk. I have a '04 3.0i that had the same issue. BMW tech diagnosis was increased resistance from dirty connection caused a low voltage condition which caused a error code/fault condition to be set.

You need to disconnect battery when disconnecting connectors/cleaning them. Not disconnecting will cause fault/error codes on many of the connections. Those codes need to be reset using the appropriate software as only a very few BMW specific error/fault conditions can be reset/cleared with a very select few OBEDII readers.

[apbx3]

Thank you very much that work all good , almost had the whole cable replaced.

[bgshaw]

I have a 2003 z4 with airbag light on. Code is 5BSR open circuit firing circuit safety battery terminal. It would not clear. I then attempted to Bypass with a 2.3 ohms 2 watt resistor and this allowed the code to be cleared but it comes back later on a re start.

I am puzzled as why the bypass allows clearing but does not fix the issue and it comes back. I checked the BST and it was not showing any resistance. I than bought a used BST that had 2.3 Ohms resistance coming from the BST. I am still not sure why the bypass is permanent fix for some but not for me. Any ideas

Barry Calgary Canada

[spunnn]

I have the same problem. I clean all conections bit the airbag fault only dissapear when i clean with the c110cable. But after restart, the airbag light comes again. The cable looks ok and i dont have An accident before. My error is 98f5 low voltage, open circuit etc, anda sometimes 98f4 short circuit....and the same.
In the e46 is possible to clear the error with bmw scanner in the srs section bit this cant be coded in the z4
Can someone help? Thankss

[Clearancediver]

Read my post in this thread. Clean the connection of the wire (not BST cable) going to the BST. It's this SRS connection which is causing the code. If the code persists it's possible the male/female connectors aren't making a good enough connection. That causes an increase in resistance and the resultant fault code. That was my problem when the problem recurred this year. I moved the male pins just a wee bit (and it wasn't more than a "impression" of movement) towards the correct side of the female connection... to ensure a tight pin to pin connection. That solved the issue.