How to determine the fault of J1939 to J1708 cable?
To determine the fault of the J1939 to J1708 cable, it is necessary to combine communication abnormalities, physical inspection, and professional tool testing to gradually identify the problem points. The following are specific judgment methods and steps:
Cable faults are usually manifested through abnormal device communication, and can be preliminarily judged from the following phenomena:
The device is unable to communicate
The two end devices (such as J1939 diagnostic instrument and J1708 ECU) cannot establish a connection or disconnect immediately after connection.
Possible reasons: cable breakage, poor interface contact, protocol conversion module malfunction.
Data transmission error
Data loss, garbled or error codes (such as checksum errors) occur during communication.
Possible reasons: Damage to the cable shielding layer may cause electromagnetic interference, internal wire short circuits, or poor contact.
Unstable communication speed
The data transmission speed fluctuates between fast and slow, or cannot reach the nominal rate.
Possible reasons: Excessive cable length can cause signal attenuation, oxidation of internal wires, or increased contact resistance.
Equipment abnormality error
The diagnostic tool prompts "communication timeout", "protocol mismatch", or abnormal device indicator lights (such as J1939 CAN bus light flashing abnormally).
Possible reasons: reversed cable polarity, incorrect pin definition, conversion module malfunction.
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