Vehicle Power Supply Cutoff Via the Power Module

Vehicle Power Supply Cutoff Via The Power Module

Customer complaints
As of model year 03/05, the following additional functional description with regard to disconnecting terminal LM is to be observed:

TIS -> Document -> SI Technology -> SBT Number 610105125

Disconnection from the vehicle electrical system by the power module can lead to the following customer complaints. These complaints are usually attributed by the customer to precisely the control module with the unusual behavior:
- Navigation system has long initialization phase (can take up to 20 minutes, loss of location data and thus strange behavior)
- Telephone loses data of number lists (TOP 8 list and list of last numbers dialed)
- ASK loses last settings (e.g. volume, last station, last function)
- CDC / DCDC runs initialization (loud noises, loss of last position and function)
- System Comfort Access is without function (vehicle can only be opened using the radio-control key or integrated key every time the power supply is cut)
- Independent heating and ventilation lose their programmed settings

Reasons for battery disconnection by the power module
The following can cause a vehicle power supply cutoff by the power module:
- Activated storage mode
- Current too high after disconnecting terminal R
- Excessive closed-circuit current
- Short circuit
- Exceeded immobilization period
- Endangered starting capability
- Execution of the diagnosis command
- Vehicle has been wakened too frequently

Storage mode
By switching over the battery switch to the OFF position, the power module goes into storage mode function 30 minutes after Terminal R switches off. The vehicle electrical system is cut off.

Current too high after disconnecting terminal R
If the current is over 120 A after disconnecting terminal R, the vehicle electrical system is shut down.

Excessive standby current
If the closed-circuit current 60 minutes after terminal R Off is over 80 mA, the vehicle electrical system is shut down.

Short circuit
If the power module detects a short circuit, the vehicle electrical system is shut down (short-circuit current 250 A).

Immobilization period exceeded
After 3 weeks' immobilization period, the vehicle electrical system is shut down. This function can be coded.

Endangered starting capability
If starting capability is endangered, the vehicle electrical system is shut down.

The starting capability depends on the mean temperature in the past few days.

Starting capability limit

Temperature Charge condition
Above 30 degrees C 30%
Below -10 degrees C Above 40%

Diagnostic command
Vehicle electrical system cut off by diagnostic command.

Vehicle has been wakened too frequently
If the vehicle is wakened too frequently after terminal R Off, the power module cuts off the vehicle electrical system. The number of wake operations can be coded and is currently set at 30. Waking can be caused by the customer or a defective component.