Ecm-To-Combination Meter Two-Way Serial Communication (Nc700X/Xa/S/Sa) - Honda NC700XA Service Manual

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GENERAL INFORMATION

ECM-to-COMBINATION METER TWO-WAY SERIAL COMMUNICATION (NC700X/XA/S/SA)

This motorcycle is equipped with the ECM-to-combination meter two-way serial communication system.
ECM sends the following information to combination meter:
– Engine speed signal
– HISS indicator signal, MIL signal, Engine oil pressure indicator signal, High coolant temperature indicator signal
Combination meter sends the following information to the ECM.
– VS sensor signal
– EOP switch line open circuit information
• The combination meter detects a problem in the VS sensor and EOP switch line.
• The combination meter diagnosis the VS sensor failure, then send the DTC 11-1 to the ECM and ECM send the MIL signal to
the combination meter.
• The combination meter send the EOP switch line open circuit information to the ECM, then ECM diagnosis the EOP switch line
failure and send the DTC 87-1 signal to the combination meter.
These signals are forwarded to the combination meter or ECM by asynchronous communication via one wire. This wire is called the
TXD/RXD line (serial communication line).
ECT SENSOR
EOP SWITCH
ECM
CKP SENSOR
IMMOBILIZER
RECEIVER
WHEN THERE IS A PROBLEM IN THE TXD/RXD LINE
When an open or short circuit occurs in the TXD/RXD line, the combination
meter indicate the following:
– MIL [1] come on.
– Engine oil pressure indicator [2] come on.
– Tachometer go off.
– High coolant temperature indicator go off.
– HISS indicator go off.
When the ECM did not receive the meter information, the ECM store the
DTC 86-1. Check the DTC 86-1 with the HDS pocket tester (page 4-12).
Check the ECM by ECM communication diagnostic mode (page 22-11).
Check the combination meter by combination meter communication
diagnostic mode (page 22-11).
1-88
TXD/RXD LINE
To COMBINATION METER:
– Engine speed signal
– HISS indicator signal
– MIL signal
– Engine oil pressure indicator signal
– High coolant temperature indicator signal
To ECM:
– VS sensor signal
– EOP switch line open circuit information
COMBINATION
METER
VS SENSOR
[1] [2]