Sleep Mode

Sleep Mode
To lower the constant battery draw when the vehicle is parked, the complete ZKE system will go into the "Sleep Mode" 16 minutes after the ignition has been switched off and no further ZKE function is active.

For example, the approximate E39 (528i) Battery draw is:
- Ignition switch off = approx 750 mA.
- One minute after = approx. 560 mA.
- After 16 minutes (sleep mode) = approx. 18 mA.

All modules in the ZKE system will go into the sleep mode. The P-Bus remains active, however no data transfer takes place until a wake-up request is received. The general module, door modules or keyless remote module can wake the system up and put the ZKE back on line. The K-Bus is active (high) in the sleep mode.

Sleep Mode Criteria: KL R, KL 15 OFF and no further function activated for 16 minutes.

Wake Up Criteria: KL R or 15 "ON" or a change in one of the signals listed below.




Battery Status
The GM monitors KL R on a dedicated circuit. If the ignition is switched on and detected via the KL R circuit but the GM does not receive KL R status via the K Bus, the GM monitors the KL R voltage level. If after an additional 0.3 seconds there is no K Bus activity, the GM initiates an emergency running program.

A substitute value for vehicle speed is used to allow the GM to operate certain functions.

The emergency running program will terminate if the GM detects a vehicle speed or KL R status via the K bus.

Diagnosis/Troubleshooting
The GM contains an EEPROM fault memory. Diagnosis and troubleshooting is carried out with the DISplus or MoDiC. The diagnostic link is through the Instrument cluster over the K bus to the GM.




Control Module Locations