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 units (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. The number of items of information varies.
  For example: the vehicle does not 'go to sleep' (sleep inhibitor); the vehicle is wakened time and again; the sidelights were 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 alternator.
    
  • Defective battery.
    
• Unfavourable customer behaviour:
  
  • Sidelights, parking light or hazard warning lights were switched on for too long.
    
  • Terminal R or terminal 15 was switched on for too long.
    
  • Long immobilisation 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 code 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 code 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 units 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 code memory in the JBE
  The causes for the 'power down' command or the reset or the cutoff of terminal 30g-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 30g.
    
  • The vehicle was awakened unexpectedly more than 20 times after cutoff of terminal 30g.
    
• 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 kilometre readings of the last 5 days
    
  • The auxiliary consumer units switched on during the last 32 cycles: for example, light or independent heating.
    
• Fault code memory in the DME/DDE
  The DME/DDE stores a fault code memory entry in the event of a closed-circuit current fault and total battery discharge.
  
• Fault code memory in the FRM (footwell module)
  The FRM is responsible for control of the lights. At terminal R off, the FRM switches the sidelights or parking light off if the voltage falls below approx. 11 Volts. On cutoff, a fault code memory entry is stored.
  At undervoltage, the LM stores a fault code 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.