Description Of Energy Diagnosis

Description Of Energy Diagnosis

Running the energy diagnosis:
The energy diagnosis is the test module to determine the cause of a flat battery. The energy diagnosis requires that charging the battery via the generator functions as a general principle. A fault in relation to the alternator can be seen from corresponding fault entries or undervoltage with the engine running.

The energy diagnosis distinguishes only the following faults:
- Battery defective / generator defective
(difficult to diagnose)
- Vehicle is continuously wakened
(cause cannot be precisely diagnosed)
- Vehicle does not go to sleep
(as a rule, cause can be diagnosed)
- Excessive closed-circuit current although vehicle asleep
(cause cannot be precisely diagnosed)
- Customer behavior
(as a rule, the result when there is no fault in the vehicle)
The customer behavior fault can be further distinguished as follows:
- Light or hazard warning lights were switched on
- Terminal R or terminal 15 was switched on
- Unfavorable driving profile
- Long immobilization period

Result of the energy diagnosis:
The energy diagnosis assumes that the vehicle had a flat battery. The 3 most likely fault causes are displayed, insofar as they can be determined. The most likely cause of the fault is in the first position. The individual results are also evaluated according to their information content.

***** - corresponds to very good information content
** - corresponds to medium information content
* - corresponds to very low information content

The energy diagnosis only provides a correct result if the fault memory has not been deleted since the fault occurred.

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. 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.

Evaluation of the energy diagnosis:
For analysis of the cause of a flat battery, a variety of diagnosis information is read from the vehicle and evaluated. This information in detail:
- Energy history memory in the SGM-SIM (Safety and Gateway Module)
The energy history memory (NB: not to be confused with the history memory for fault memory entries) stores a variety of information regarding bus messages that can help in searching for the cause of a flat battery. The energy history memory consists of 100 entries in a ring memory. If a new entry is stored, the oldest entry is overwritten. A new entry in the energy history memory is stored under one of the following conditions:
- The vehicle is in the idle state and is wakened.
- After 30 minutes terminal R off, at least one control module prevents the vehicle from going to sleep (a separate entry is made for each control module)
- The vehicle detects that the starting capability limit of the battery has been reached
- The vehicle detects undervoltage

For each entry, the following information is stored:
- The relative time and kilometer reading of the instrument cluster
- Status of terminal R at the moment of the entry
- For a unit preventing the vehicle from sleeping:
- the control module that prevented sleeping at the moment of the entry
- When the vehicle is wakened:

the bus system that wakened at the moment of the entry.

It cannot be identified which control module wakened. The reason is that the SGM-SIM is in the idle state at the moment of the wake-up message.

- Fault memory in the PM (Power Module)
Fault entries are stored in the PM when terminals 30 U and terminal 30 B are disconnected from the battery. For each disconnection reason of the PM, there is a separate fault entry. In addition, in the case of undervoltage, a fault entry with important environment related conditions is stored. The following fault entries are evaluated by the energy diagnosis:
- Power module disconnection due to excessive closed-circuit current
Environmental condition: Level of the closed-circuit current
(disconnected by PM even if the vehicle does not go to sleep)
- Undervoltage
Environmental condition: Status terminal R, status terminal 15, status whether a statutory consumer unit was switched on (e.g. light or hazard warning lights)

- Diagnosis requests to the PM (Power Module)
The PM stores various diagnosis data that is used for the energy diagnosis:
- The last registered battery replacement
- The state of charge of the battery in the last 9 days
- The kilometer readings of the last 9 days