Circuit Description

Multiplex Integrated Control System

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 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) transmits information at 33.33 kbps and the fast controller area network (F-CAN) transmits information at 500 kbps. Both networks share information among 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.

The driver's door lock switch links directly to the driver's MPCS unit and the front passenger's door lock switch links directly to the front passenger's MPCS unit. All lock and unlock commands from this switch are communicated across the multiplex integrated control system to the MICU.

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:
- AcuraLink Control Unit (XM Receiver)
- Adaptive Front Lighting Control Unit
- Gauge Control Module
- Driver's MPCS Unit
- Combination Switch Control Unit
- Climate Control Unit
- HandsFreeLink Control Unit
- MICU
- Power Seat Control Unit
- Relay Control Module
- Keyless Access Control Unit

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

For safety reasons, a backup circuit is 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.

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:
- AcuraLink Control Unit (XM Receiver)
- Adaptive Cruise Control Unit
- DLC
- E-pretensioner Unit
- Gauge Control Module
- Navigation Unit
- PCM
- SH-AWD Control Unit
- 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.