How the Circuit Works

Multiplex Integrated Control System (MICS)

How the Circuit Works
The multiplex integrated control system sends digital signals between control units through shared wires to reduce the number of wires in order to make harnesses lighter.

The input signals from each switch are converted to digital signals within the receiving control unit. The digital signals are sent from one control unit to another as serial data over dedicated communication lines. When the appropriate control unit receives the digital signal, it converts the signal back to an operational command, such as operating a relay. The multiplex integrated control system schematic shows its' power, grounds, and communication lines. The ignition key light and roof console are shown because they are used to blink DTC's when the system is in the self-diagnostic mode.

There are two different networks within the multiplex integrated control system, they are:
- Body Controller Area Network (B-CAN)
- Fast Controller Area Network (F-CAN)

The body controller area network (B-CAN) and fast controller area network (F-CAN) share information between multiple electronic control units and work together to form the multiplex integrated control system. The gauge control module translates information from B-CAN to F-CAN and from F-CAN to B-CAN to allow the networks to share information.

B-CAN Network
B-CAN information is transmitted across the communication lines at a slower speed for convenience related operations that do not require a high process speed. The following control units operate on the B-CAN network:
- Combination Switch Control Unit
- Display Panel Control Unit
- Gauge Control Module
- HandsFreeLink Control Unit
- MICU
- Power Seat Control Unit
- Power Window Master Switch Relay Control Module

The following Systems are related to the B-CAN network:
- DPMS
- Entry Light Control System
- Exterior Lights
- Gauges and Indicators
- HandsFreeLink System
- Horns
- HVAC
- Interior Lights
- Interlock System
- Key Light Timer System
- Moonroof
- Oil Pressure Indicator System
- Power Door Locks/Keyless Entry/Security Alarm
- Power Windows
- Rear Window Defogger
- Reminder Systems
- Safety Indicator
- Wiper/washer

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
- Gauge Control Module
- Navigation Unit (Navigation)
- VSA Modulator-Control Unit
- TPMS Receiver Unit ('06)

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

For safety reasons, a backup circuit is also added to the headlight and wiper/washer circuits of the B-CAN network in the event of a network wire, or control unit failure that would effect the system operation.