BMW puts a pyrotechnic disconnect on the battery positive cable, and 0X930991 reports that safety battery terminal circuit shorted to ground. The device cuts the main power feed in a serious crash to reduce fire risk.
The safety battery terminal, sometimes called the battery safety terminal, is a small charge built into the positive cable clamp. When the ACSM decides a crash is severe enough, it fires that charge and physically separates the high current feed from the starter and alternator cables. Because it is a pyrotechnic device on a monitored circuit, the module watches it and stores 0X930991 when it reads ground on that circuit.
The terminal sits right on the battery, which on many BMW models is in the trunk or under the rear seat. Battery replacements, jump starts, trunk work, and corrosion at the post all happen in that exact spot. A control wire grounded against the battery tray or the body while somebody was working on the battery is a common way for this code to appear.
0X930991 reports a condition the module is measuring right now, which puts it in the live fault group. Repair the circuit and the entry goes away. A crash record is written only when the restraint system fires, it describes an event instead of a reading, and it stays in the module permanently until the module is reset or replaced.
The reset is not the answer to a shorted control wire. Repair the wiring at the battery, then clear. If the safety terminal already fired in a collision, the terminal is single use and has to be replaced with a new one before the system will read correctly. In that situation the ACSM is normally holding crash data as well, and our mail-in reset clears that record after the terminal and other parts are replaced.
BMW is the make for 0X930991. The pyrotechnic battery disconnect is a BMW design feature, and the hex code comes from BMW diagnostic software.
Go straight to the battery and look at the positive terminal, because the wire and connector on the safety terminal are right there and easy to inspect. Check whether the device has already fired, which usually shows as a separated or discolored clamp body. Corrosion at the connector gets cleaned and the wiring gets repaired before any code clearing, and we can help identify a replacement terminal at 501-988-0611. Related codes: 0X930985, 0X9309A9, B1656.
Trace the wiring and connectors first. If the module still holds the fault after the repair, mail it to us and we will clear it.
Genuine OEM, tested, and shipped ground from Jacksonville, Arkansas.
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