Information Bus: Description and Operation

How the Circuit Works

The conventional portion of the electrical system carries DC power through separate wires to each component. The multiplex portion of the system, however, sends digital signals between control units through shared wires to reduce the number and weight of wire harnesses. The signals from each switch are converted to digital signals within the receiving multiplex control unit. The digital signals are sent from the multiplex control unit to other control units as serial data over dedicated communication lines. When the appropriate control unit receives the digital signal, it converts the digital signal back to a switch signal and operates the related components.

The multiplex control system schematic shows its power, grounds, and communication lines. The ignition key light and front ceiling light are also shown because they are used to blink DTCs in the system's self-diagnosis function. The rest of the multiplex control system wiring is shown in the following circuit schematics:
- A/T Controls
- Ceiling Lights
- Charging System
- Dash and Console Lights (brightness control)
- Entry Light Control System
- Fans
- Gauges and Indicators
- Headlights
- Horns
- HVAC
- Interlock System
- Key-in Reminder
- Lights-on Reminder
- Power Door Locks
- Spotlights
- Seat Belt Reminder
- SRS
- Wiper/Washers

F-CAN Network
F-CAN information is transmitted across the communication lines at a faster speed for real time functions such as fuel, emissions, and traction control data. The following control units operate on the F-CAN network:
- ECM/PCM
- DLC
- Gauge Control Module
- TPMS Control Unit
- VSA Modulator-Control Unit

Since messages on the F-CAN network are typically of higher importance, a second wire is used for communication circuit integrity monitoring.