Energy Diagnosis: Waking Up The Vehicle

Energy Diagnosis: 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 units. 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 unit" 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 unit.

Brief component description

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

Control unit name Possible reasons for waking (authorized wakings)
CAS Car Access System - Operation of the START-STOP button.
- Ejection of remote control / identification sensor from the slot.
- Operation of the centre lock button.
- Operation of the remote control.
- Bonnet contact switch.
- Door-handle contact, front left and front right.
- Wake-up line.
CA Comfort Access - Comfort access
FRM Footwell module - Consumer unit shutdown.
- Door contact, rear left and rear right.
- Door contact, front left and front right.
- Door lock, front left.
- Interior lighting button.
- Hazard-warning switch.
- Light switch.
- Steering-column lever, flashing left or right.
- Headlight flasher.
JBE junction box electronics - Luggage compartment button and luggage compartment lock.
- Hotel position switch.
- Triggering the acoustic and visual alarm.
- Wake-up wire.
KOMBI Instrument cluster - Coolant temperature data request to engine-management electronics.
CHAMP multimedia platform - Pressing the rotary push button for volume control.
RAD/RAD2 radio - Pressing the rotary push button for volume control.
FZD Roof functions centre - Triggering the acoustic and visual alarm.

Notes for Service department

General notes

Troubleshooting in the event of a problem with too many unauthorized wakings
The vehicle is not permitted to wake any of the control units not mentioned above. In the event of errors 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 errors (frequent unauthorized waking), the following possible causes are to be checked:
- Defective peripherals of the cause (for example defective sensor or switch).
- Defective control unit.
- Wake-up cable for causes connected to the PT-CAN (for example, loose contact).

NOTE: If a number of control units are registered at irregular intervals as wakings at the same kilometer reading, the vehicle was wakened by the customer or work in the workshop: Frequent opening and closing of the vehicle doors, tailgate or engine compartment lid when the vehicle is parked. Do not replace registered control units.

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