Honda Accord 2008 Manual page 2139

07/11/02 09:30:22 61TA0000_220_0109
Multiplex Integrated Control System
System Description (cont'd)
Wake-up and Sleep Function
The multiplex integrated control system has ''wake-up'' and ''sleep'' functions to decrease parasitic draw on the
battery when the ignition switch is to LOCK (0).
• In the sleep mode, the multiplex integrated control system stops functioning (communication and CPU control)
when it is not necessary for the system to operate.
• As soon as any operation is requested (for example, a door is unlocked), the related control units in the sleep mode
immediately wake up and begin to function.
• When the ignition switch is turned to LOCK (0), and the driver's door is opened, then closed, there is a delay about
40 seconds before the control unit goes from the wake-up mode to the sleep mode.
• The sleep mode will not function if any door is opened or if a key is in the ignition.
• The draw is reduced from 200 mA to less than 35 mA when in the sleep mode.
NOTE: Sleep and Wake-up Mode Test (see page 22-127).
Fail-safe Function
To prevent improper operation, the MICUs have a fail-safe function. In the fail-safe mode, the output signal is fixed
when any part of the system malfunctions (for example, a faulty control unit or communication line).
Each control unit has a hardware fail-safe function that fixes the output signal when there is a CPU malfunction, and a
software fail-safe function that ignores the signal from a malfunctioning control unit , which allows the system to
operate normally.
Hardware Fail-safe Control
Fail-safe function
When a CPU problem or a abnormal power supply voltage is detected, the MICUs move to the hardware fail-safe
mode, and each system output load is set to the pre-programmed fail-safe value.
Software Fail-safe Control
When any of the data from the B-CAN circuit cannot be received within a specified time, or an unusual combination of
the data is recognized, the MICUs move to the software fail-safe mode. The data that cannot be received is forced to a
pre-programmed value.
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