System Description

SYSTEM DIAGRAM

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OUTLINE

The BCM reads the status of the combination switch and recognizes the status of each switch.
The BCM has a combination of 6 input terminals (INPUT 1 - 6) and 6 output terminals (OUTPUT 1 - 6) and reads a maximum of 22 switch states.

COMBINATION SWITCH MATRIX

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Combination switch INPUT-OUTPUT system list

System	INPUT 1	INPUT 2	INPUT 3	INPUT 4	INPUT 5	INPUT 6
OUTPUT 1	Check diode 1	INT volume 1	Front washer switch	Front wiper LO	INT volume 2	Front wiper OFF
OUTPUT 2	High beam switch	Check diode 2	Rear washer switch	Front wiper HI	INT volume 3	Front wiper MIST
OUTPUT 3	Passing switch	Low beam switch	Check diode 3	Front wiper INT	Rear wiper INT	-
OUTPUT 4	Rear fog switch	AUTO light switch	Turn signal LH	Check diode 4	Rear wiper ON	-
OUTPUT 5	Front fog switch	Tail lamp switch	Turn signal RH	Light OFF switch	Check diode 5	-
OUTPUT 6	-	-	-	-	-	Check diode 6

COMBINATION SWITCH READING FUNCTION

Description

The BCM reads the status of the combination switch at 10 ms intervals normally.

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The BCM operates as follows and judges the status of the combination switch.
- It operates the transistor on INPUT side in the following order: OUTPUT 6-> 5 -> 4 -> 3 -> 2 -> 1, and outputs voltage waveform.
- The voltage waveform of OUTPUT corresponding to the formed circuit is input into the interface on the INPUT side if any (1 or more) switches are ON.
- It reads this change of the voltage as the status signal of the combination switch.
  
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Operation Example

In the following operation example, the combination of the status signals of the combination switch is replaced as follows: INPUT 1 - 6 to " - " and OUTPUT 1 - 6 to " - ". Example 1: When a switch (Turn signal RH) is turned ON

The circuit between INPUT 3 ( ) and OUTPUT 5 ( ) is formed when the Turn signal RH is turned ON.

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The BCM detects the combination switch status signal " " when the signal of INPUT 3 is input to OUTPUT 5.
The BCM judges that the Turn signal RH is ON when the signal " " is detected.

Example 2: When multiple switches (Front fog switch, Turn signal RH) are turned ON

The circuits between INPUT 1 ( ) and OUTPUT 5 ( ) and between INPUT 3 ( ) and OUTPUT 5 ( ) are formed when the Front fog switch and Turn signal RH are turned ON.

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The BCM detects the combination switch status signal " " when the signals of INPUT 1 and INPUT 3 are input to OUTPUT 5.
The BCM judges that the Front fog switch and Turn signal RH are ON when the signal " " is detected.

WIPER INTERMITTENT DIAL POSITION (WITH WIPER INTERMITTENT DIAL POSITION)

The BCM judges the wiper intermittent dial 1 - 5 by the status of INT volume 1, 2 and 3 switches.

Wiper Intermittent Dial Position	Switch Status
Wiper Intermittent Dial Position	INT volume 1	INT volume 2	INT volume 3
1	ON	ON	OFF
2	ON	OFF	OFF
3	OFF	OFF	OFF
4	OFF	OFF	ON
5	OFF	ON	ON

NOTE:

For details of wiper intermittent dial position: Refer to System Description .