System Components

System Components

General Module (GM): The GM is reponsible for the operation and central coordination of body electronics. The GM is a micro-computer that is the central component (heart) of the Central Body Electronics. The GM is located behind the glove box.




The main objectives for using the GM are:
- Increase Overall Reliability
- Centralize Electronic Systems
- Decrease Assembly and Service Repairs
- Centralized Diagnosis of all ZKE Components
- Individualization of Features (Coding)

The GM requires input commands to perform Central Body Electronics functions. The inputs are supplied by digital switched signals such as:







- Trunk Lock Microswitch - supplies voltage (KL 30) to the GM when switched. A path to ground is provided by the GM (internally).The GM monitors the switched input voltage.
- Central Lock Button - supplies a ground circuit to the GM when switched. The GM supplies and monitors a reference voltage (5v) that is "pulled" low when the switched ground path is provided.







The GM processes the input information and contains "coded" instructions that allow a specific output control of functions.

The GM will produce output functions using internal transistors to switch current flow (providing voltage or ground) through circuits and actuators. Actuators are the final controlling devices used by the GM to operate or control various output functions such as relays and motors.

The ZKE III system offers an overall reduction in vehicle wiring particularly in the areas subject to wear from movement such as doors, seats and the steering column. To accomplish this, the "P-Bus" is used to interface (signaling) with peripheral modules over a single wire. The ZKE III modular system consisting of the following components:
- General Module III = Main controller for ZKE functions
- PM - SB/FT = Driver's door switch block and door module
- PM - BT = Passenger's door module
- PM - SHD = Sunroof module
- PM - SM = Seat/Mirror/Steering Column memory module
- AIC = Rain Sensor (if equipped)




All modules communicate through the P-Bus and GM III onto the K-Bus for diagnosis.

The following is an overview of new or changed features found on the E53 ZKE III variant:
- Passenger's door module is incorporated into the passenger's door's switch block
- Sunroof module (SHD) is located on the P-Bus.
- The Central Locking system uses a door lock actuators with hall effect sensors.
- The GM III is responsible for the Key Memory feature.

The E53 ZKE III system continues to be a modular system consisting of the following:
- General Module III = Main controller for ZKE functions
- PM - SB/FT = Driver's door switch block and door module
- PM - SB/BT = Passenger's door module/Window switch
- PM - SHD = Sunroof module
- PM - SM = Seat/Mirror/ Steering Column memory module
- AIC = Rain Sensor (if equipped)




All of these modules communicate over the "K-Bus and P-Bus" for signaling purposes and diagnosis.