Effects Of Disconnection Or Total Discharge Of Battery On Electrical Systems In The Vehicle And Precautions To Be Taken
Information
Control unit memories
Values and faults stored in the control units can be deleted if the battery is disconnected or completely discharged.
- If possible, a VAL (Vehicle Analysis Log) should be created and stored before disconnecting the battery.
Information
Supply voltage fault entry
The entry "supply voltage" may be stored in various control units if the battery has been completely discharged.
- Delete the "supply voltage" entry from the control units in question.
Information
Ready status
In some countries (presently the USA and Canada), after disconnecting the battery, it is necessary to reach the Ready status by performing a test drive and/or by using the Porsche System Tester (DME control unit menu). If in doubt, contact the relevant importer.
Information
DME control unit
With all DME systems, the engine must run fur several minutes before the engine control module can relearn the idle speed and mixture adaptation values!
After disconnection of the power supply, the idle speed might change or fluctuate briefly until the throttle valve adjusting unit has been readapted.
The mixture adaptation is also lost.
After the battery is connected:
With the DME, it is necessary to carry out a teaching and adaptation routine as described below:
- Switch ignition on for 30 seconds without starting the engine.
- Do not actuate accelerator pedal.
This completes the adaptation of the throttle valve adjusting unit.
Information
Tyre Pressure Monitoring (TPM)
When the battery is disconnected and connected, the tyre pressure is first displayed as "- - -".
- Once the battery has been disconnected and work is complete, the vehicle must be driven for a short distance.
The actual pressures will then be displayed again.
Information
6452 Power windows
The limit positions of the power windows are deleted from the control unit when the battery is disconnected and connected.
Perform the following procedure for all power windows:
- Pull rocker switch and fully close window once.
- Pull rocker switch once more.
The upper end position of the window is stored.
- Press rocker switch and fully open window once.
- Press rocker switch once more.
The lower end position of the window is stored.
- Erase error messages from the control units.
- Perform the required initialisation steps, depending on vehicle equipment.