Unfavourable customer behaviour with vehicle faults is a possible cause of breakdowns due to a depleted battery. In detail, the following individual causes can be determined:
If the vehicle does not reach the idle state after terminal R Off, i.e. the bus systems remain active, the causing control unit is normally determined by the energy diagnosis.
The troubleshooting must be continued in the peripherals (e.g. defective sensor or switch) of each control unit. If no fault is determined, replace the control unit.
If a number of control units on the PT CAN bus with the same kilometre reading are entered as cause in the energy history memory (e.g. EKP, DSC and SZL on diesel model or DME, DSC and SZL on vehicles with petrol engines), the wake-up line should be checked:
For vehicles produced before 12/2006:
If terminal 15 can no longer be switched using the START-STOP button or the electrical steering interlock (ELV) cannot be unlocked, check the installation location of the battery for traces of dampness and examine the fault code memory entries regarding the IBS: IBS can be defective due to moisture and keep the wake-up line at high level. In this case, replace the IBS.
In this case, replace the IBS. For vehicles produced after 12/2006, a new water-tight IBS is used.
Important!
Operation by the customer can also lead to an entry in some control units: e.g. listening to the radio with terminal R OFF leads to the registration of the head unit (M-ASK or CHAMP with the same kilometre reading as cause in the energy history memory.
If the vehicle is wakened time and again, the maximum number of wakings in an off-load phase (terminal R off) for the last 5 weeks in each case and the IDs of the last 26 waking messages of the K CAN are determined by the energy diagnosis. In some cases, the causing control unit is determined by the energy diagnosis.
If it is possible to determine the waking control unit, troubleshooting must then be continued in the peripherals (e.g. defective sensor or switch, loose contact) of the control unit. If no fault is determined, the control unit must be replaced.
Note: In exceptional cases, it is possible that the result ”Vehicle keeps being woken up” is generated by unfavourable customer behaviour. (E.g. frequent waking of the vehicle at terminal R off by opening and closing the luggage compartment lid or doors.)
The result ”Excessive closed-circuit current” means that the vehicle, occasionally at least, has had a closed-circuit current greater than 80 mA. Here, the vehicle was in the idle state, that is, the bus systems were inactive. A possible cause of this could be defective control units. As troubleshooting, run a closed-circuit current measurement and identify possible causes by disconnecting fuses or disconnecting the corresponding control units step by step.
Procedure for external closed-circuit current measurement: see Service Information number 61039947.
Even though the battery was not the cause of the complaint, it might have been damaged beforehand due to deep discharge for a longer period. For this reason, check the battery condition if you suspect that the battery might have been damaged beforehand.
See ”Master document, battery” BMW Service Technology:
TIS -> Document -> Service Information -> Enter Number
SI number: 610702875
If there is a suspicion that the alternator is defective, it must be determined whether the DME/DDE has relevant fault code memory entries. Fault code memory entries with regard to the IBS must also be taken into account.
If the vehicle comes to a standstill and will not start during or shortly after a journey, the cause probably lies in the charge balance of the alternator. A requirement here is that the charged battery was still able to deliver adequate current for the starting operation.