Part 2

Diagnosis instruction

Energy diagnosis
A breakdown due to a flat battery or problems in the vehicle electrical system can have wide variety of causes. In most cases, the cause does not lie with the battery itself. For this reason, replacing the battery will only rarely provide a sustained solution to the problem. Instead, a systematic diagnosis of the source of the fault is necessary.

Faults are often no longer present when the vehicle comes to the workshop. This is why data stored in the vehicle is the basis for diagnosis. Information on the battery status as well as functional processes in the various bus systems are stored in the corresponding control modules.








This information can be called up and evaluated by the BMW diagnosis system. The BMW diagnosis system has a test module for this. The test module for energy diagnosis reads all the relevant data from the corresponding control modules.

The following information is displayed:
- Conspicuous information
An entry is only made when a fault is presumed.
- Standard information
This information can always be displayed.

The energy detects the following faults:
- Operating faults
- Fault on the vehicle

- Operating faults
- Sidelights, parking lights or hazard warning lights were switched on for too long with the vehicle parked.
- Terminal R or terminal 15 were switched on for too long while the engine was off.
- Immobilization period of the vehicle was too long.
- Frequent short distance driving with a number of current consumer units switched on

- Faulton the vehicle
- Battery defective
- Alternator defective
- Excessive closed-circuit current, at times greater than 80 Milliampere mA) with inactive bus systems
- Vehicle does not "go to sleep": the vehicle does not reach the idle state; the bus systems remain active.
- Vehicle keeps being woken up

Notes on coding / programming
The data of the battery is coded in the Car Access System (CAS). The data can be read out using the BMW diagnosis system.

No liability can be accepted for printing or other faults. Subject to changes of a technical nature

Description of the energy diagnosis

Running the energy diagnosis
A breakdown due to a depleted battery or problems in the vehicle energy system can have a wide variety of causes which, in most cases, are not caused by the battery itself. For this reason, replacing the battery will only rarely provide a sustained solution to the problem. The energy diagnosis test module helps find the cause of the problem.

Result of the energy diagnosis
The test module reads all the necessary data from the corresponding control modules (see below). After evaluating this data, it displays the following information:
- Conspicuous information: this information is only displayed if there was a problem in the vehicle energy system. For example: the vehicle does not 'go to sleep' (sleep inhibitor); the vehicle is wakened time and again; the position light was switched on for too long, etc.
- Standard information: this information can always be displayed (evaluation of the closed-circuit current monitoring, information on the battery, for example battery charge statuses of the last 5 days, driving profile, stationary profile).

On the basis of this information, it can then be decided what the real cause of the fault is.

Overview of possible causes
A breakdown due to a depleted battery or a problem in the vehicle energy system is not necessarily the result of a defective battery. However, in some cases the battery can be damaged- no matter what the cause. The various causes can be placed in two main categories:
- Vehicle faults:
- The vehicle does not "go to sleep".
- The vehicle keeps being woken up.
- Excessive closed-circuit current.
- Defective generator.
- Defective battery.

- Unfavorable customer behavior:
- Position light, parking light or hazard warning lights were switched on for too long.
- Terminal R or terminal 15 was switched on for too long.
- Long immobilization period.
- Unfavourable driving profile.

Data from the vehicle that is read and evaluated
For energy diagnosis, the evaluated data in the vehicle is not changed.The energy diagnosis can be run a number of times and normally always provides the same result.

The energy diagnosis normally provides the same result after repairs, as the data is still present in the vehicle. The waking registration section is only deleted from the energy history memory when a waking analysis has been carried out. Even after deleting the fault memory, the data from the energy history memory is still stored. However, at the latest when the energy history memory is overwritten with new data, the repaired fault cause is no longer displayed as result of the energy diagnosis.

This data in detail:
- Energy history memory in the JBE (Junction Box Electronics)
The energy history memory (NB: not to be confused with the history memory for fault memory entries) stores a variety information that can help in searching for the cause of problems in the vehicle energy system. The stored information of the energy history memory in detail:
- The maximum number of wakings within an off-load phase (terminal R off within the last 5 weeks
- The last 5 control modules that prevented the vehicle from going to sleep (with frequency and last kilometre reading of each event)
- The driving profile of the last 5 weeks
- The last 50 CAN messages that woke the K-CAN bus (with kilometre reading of each event)

- Fault memory in the JBE
The causes for the 'power down' command or the reset or the cutoff of terminal 30 g-f are stored in the JBE. There are the following fault cases:
- The battery reached the starting capability limit at terminal R off.
- The vehicle is not yet in the idle state 10 minutes after cutoff of terminal 30 g.
- The vehicle was awakened unexpectedly more than 20 times after cutoff of terminal 30 g.

- Diagnosis requests of the DME/DDE
The DME/DDE stores various data that is used for the energy diagnosis:
- The last 32 cycles of the closed-circuit current monitoring or the closed-circuit current histogram are stored
- The last registered battery replacement
- The state of charge of the battery in the last 5 days
- The kilometer readings of the last 5 days
- The auxiliary consumer units switched on during the last 32 cycles: for example, light or independent heating.

- Fault memory in the DME/DDE
The DME/DDE stores a fault memory entry in the event of a closed-circuit current fault and total battery discharge.

- Fault memory in the FRM (footwell module)
The FRM is responsible for control of the lights. At terminal R off, the FRM switches the sidelight or parking light off if the voltage falls below approx. 11 Volts. On cutoff, a fault memory entry is stored.
At undervoltage, the LM stores a fault memory entry. The environment related conditions can be used to determine whether terminal R, terminal 15 or a statutory consumer unit (e.g. light or hazard warning lights) was switched on.

Possible causes- vehicle faults
Unfavorable customer behavior with vehicle faults is a possible cause of breakdowns due to a depleted battery. In detail, the following individual causes can be determined:

Vehicle does not "go to sleep"
If the vehicle does not reach the idle state after terminal R Off, i.e. the bus systems remain active, the causing control module is normally determined by the energy diagnosis. The troubleshooting must be continued in the peripherals (e.g. defective sensor or switch) of each control module. If no fault is determined, replace the control module.

If a number of control modules on the PT-CAN bus are entered as cause in the energy history memory at the same kilometre reading, the wake-up line should be checked:
- Short circuit to ground or positive
- Loose contact
- First, check the connections of the wake-up line on the IBS, CAS and JBE

Important! Operation by the customer can also lead to an entry in some control modules: 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.

Vehicle keeps being woken up
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 50 waking messages of the K CAN are determined by the energy diagnosis. The causing control module is normally determined by the energy diagnosis. If it was possible to determine the waking control module, troubleshooting must then be continued in the peripherals (e.g. defective sensor or switch, loose contact) of the control module. If no fault is determined, the control module 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. frequently waking the vehicle at terminal R OFF by opening and closing the luggage compartment lid or doors.

Excessive standby current
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 modules. As troubleshooting, run a closed-circuit current measurement and identify possible causes by disconnecting fuses or disconnecting the corresponding control modules step by step.

Procedure for external closed-circuit current measurement: see Service Information number 61039947.

Battery or generator defective
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 -> SI Technology -> Enter SI number

SI number: 610702875

If there is a suspicion that the generator is defective, it must be determined whether the DME/DDE has relevant fault memory entries. Fault 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 generator. A requirement here is that the charged battery was still able to deliver adequate current for the starting operation.

Possible causes - unfavorable customer behavior
Unfavorable customer behavior with vehicle faults is a main cause of breakdowns due to a depleted battery. In detail, the following individual causes can be determined:

Position light, parking light or hazard warning lights were switched on
The position light, parking light or hazard warning lights were switched on for too long with the vehicle parked. If possible, point out these facts to the customer.

Terminal R or terminal 15 was switched on
Terminal R or terminal 15 were switched on for too long while the engine was off. The current consumption of the vehicle is then, depending on the equipment, 10-15 A. This discharges the battery very quickly. If possible, point out these facts to the customer.

Long immobilization period
The vehicle was parked for a very long period. The vehicle has a standard closed-circuit current consumption of 10-40 mA, depending on the equipment fitted. This leads to slow but continuous battery discharge. Depending on the state of charge of the battery when the vehicle is parked, the residual capacity necessary to start the vehicle is reached after an immobilization period of approx. 4- 12 weeks. If possible, point out these facts to the customer.

Unfavorable driving profile

The battery can be depleted due to unfavorable driving characteristics of the customer:-
- In the case of extreme short-distance driving, it is possible that starting the engine takes more energy from the battery than is charged in the subsequent trip. The charge balance deteriorates if a great many current consumers are switched on during the subsequent trip.
- Very few trips: If the vehicle is moved very infrequently and the individual trips are not sufficiently long, it is possible that during the immobilization period more energy is taken from the battery by normal closed-circuit current than is charged while the vehicle is being driven. If possible, point out these facts to the customer.

Terminal control and terminal assignment
For more information; see general functional description of the power supply:
Function selection -> Complete vehicle -> Body -> Power supply

Brief description
The power supply for the consumer units is delivered via various terminals. The terminal control is distributed across various control modules:





- Terminal 30: Continuous +
Terminal 30 is routed from the battery terminal via the safety battery terminal to the front








- Terminal 30 g: Switched continuous +
Terminal 30 g is controlled by the CAS. When the vehicle is wakened by an operation of the user, terminal 30 g is switched on. Terminal 30 g is switched off automatically after a codable after-run time (e.g. 30 minutes). As in the case of terminal 15, the CAS activates a relay in the rear distribution box and in the front distribution box across semiconductor switches. Control modules supplied by terminal 30 g (rear distribution box):








Control modules supplied by terminal 30 g (front distribution box):





- Terminal 30 g-f: Cutoff in the event of faults
Terminal 30 g-f is a terminal 30 that is only switched off if faults are detected. The JBE controls terminal 30 g-f via a bistable relay in the rear distribution box. The bi-stable relay can be switched on and off. As a rule, the bistable relay is always switched on. Control modules supplied by terminal 30 g-f (rear distribution box):





- Terminal 15:
The CAS controls terminal 15 depending on actuation of the start-stop button (with remote control inserted or identification sensor in the insert compartment). Terminal 15 is activated in the CAS via semiconductor switches. A relay in the rear distribution box is activated via the output of a semiconductor switch. Control modules supplied by terminal 15 (rear distribution box):

- Terminal R:
The CAS controls terminal R.

Waking up the vehicle

Registration of the waking in the JBE
K-CAN bus wakings can be recognized by the JBE and allocated to the individual control modules. The last 50 CAN messages that woke the K-CAN bus are stored in the energy history memory in the JBE. The relative time from the instrument cluster and the kilometer reading are also stored as marginal conditions.

However, no distinction can be made between authorized and unauthorized wakings.

Note:
If the test module is unable to interpret the waking CAN message, "unknown control module" is displayed as waking. This can have the following possible causes:

- JBE was unable to recognize the waking CAN message properly.
- The stored CAN message cannot be allocated to any control module.

Brief description of components

Waking registration in the junction box electronics
The JBE contains another processor, a so-called co-processor. As the JBE itself 'goes to sleep in the idle state, thus switching off the main process, the JBE would not notice a brief waking. With the other processor, the K-CAN bus can be permanently monitored and the waking attempts stored in the energy history memory.

System functions
The wakings are recorded in the time span between terminal "R off" and terminal "R on". Due to the electrical processes in the idle state of the vehicle, wakings also occur when the vehicle is fully intact. This means that when these wakings are evaluated the wakings that normally occur are to be taken into account:








Authorized waking





Recording wakings
Difference between normal case A and failure frequent waking B (see illustration above).
1. Terminal R OFF
2. Waking FRM (8 minutes after terminal R Off): Consumer shutdown only if the vehicle is not locked.
3. Waking instrument cluster (KOMBI) (40 minutes after terminal R Off): Query of the coolant temperature. Waking does not always occur, only under certain conditions.
4. Waking instrument cluster (KOMBI) (80 minutes after terminal R Off): Query of the coolant temperature. Waking does not always occur, only under certain conditions.
5. Authorized wakings: see table above.

Notes for Service department

General information

Troubleshooting in the event of a problem with too many unauthorized wakings
The vehicle is not permitted to wake any of the control modules not mentioned above. In the event of faults in the energy diagnosis test module or in the service function for analysis of the waking, they are recognized as unauthorized wakings. In the event of faults (frequent unauthorized waking), the following possible causes are to be checked:
- Defective peripherals of the cause (for example defective sensor or switch).
- Defective control module.
- Wake-up cable for causes connected to the PT-CAN (for example, loose contact).

Diagnosis instructions
Observe the instructions in the diagnosis system: energy diagnosis test module and service function for the analysis of wakings.

Failure: inhibited sleeping








The events in the case of an inhibited waking are described below. In the event of a fault, all the measures serve to ensure the starting capability of the vehicle and for diagnosis if the fault has caused a flat battery.

Failure: too many wakings








The events in the case of too many wakings are described below. In the event of a fault, all the measures serve to ensure the starting capability of the vehicle and for diagnosis if the fault has caused a flat battery.

In the top example, only two authorized wakings are shown:
- Waking FRM (8 minutes after terminal R Off): Load deactivation
- Waking instrument cluster (KOMBI) (40 minutes after terminal R Off): Query of the coolant temperature. Waking does not always occur, only under certain conditions.

Terminal 30 g-f: bi-stable relay
For more information; see general functional description of the power supply:
Function selection -> Complete vehicle -> Body -> Power supply

Brief description
In the event of a fault, the relay terminal 30 g-f switches the connected consumer units off.
The relay terminal 30 g-f is a bi-stable relay and is fitted on the rear board of the distribution box.
The relay is activated by the junction box electronics (JBE). The bi-stable relay has two relay coils that open or close the relay contact on activation. The relay persists in the last activated position (contact open or closed).
In the normal case, terminal 30 g-f is always switched on. With terminal R or terminal 15, terminal 30 g-f is always switched on.