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ON-BOARD DIAGNOSTIC SYSTEM EXTERNAL TESTER COMMUNICATION FUNCTION

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• The external tester communication function communicates diagnostic information (reading DTCs, reading input/output signal, driving output parts) by sending and receiving signals between the ABS HU/CM and external tester.

Connection and communication information

| External tester
--- | ---
WDS or equivalent
Connection | Communication method
On-board diagnostic (malfunction detection) function | Input/output: KLN signal | Serial communication
Data monitor function | Input/output: KLN signal | Serial communication
Active command modes function | Input/output: KLN signal | Serial communication

## Serial Communication

• Serial communication (synchronous communication) is a method of communication in which many pieces of information are sent and received instantaneously through a single wire.
• By connecting the WDS or equivalent to DLC-2, diagnostic information can be sent and received between the WDS or equivalent and the ABS HU/CM via the KLN terminal.
• The ABS HU/CM receives signals for the malfunction detection function, data monitor function, and active command modes function from the WDS or equivalent, and sends information about DTCs and input/output part operating conditions to the WDS or equivalent.

Diagnostic function | Signal received | Signal sent
--- | --- | ---
Malfunction detection function | DTC verification signal | DTC
Data monitor function | Request signal to read selected monitor item | Monitor information for requested monitor item
Active command modes function | Request signal to read selected active command modes item | Output part drive signal