Yamaha MTN850-A 2017 Service Manual page 481

Self-diagnosis and servicing
The ABS ECU has a self-diagnosis function. By utilizing this function, quick problem identification and
service are possible. Previous malfunctions can be checked since the ABS ECU also stores the mal-
function history.
The fault codes recorded in the ABS ECU can be checked using the Yamaha diagnostic tool. When the
service is finished, check the normal operation of the vehicle, and then delete the fault code(s). For in-
formation about deleting the fault codes, refer to "[B-3] DELETING THE FAULT CODES" on page
8-147. By deleting the fault codes stored in the ABS ECU memory, it is possible to pursue the cause
correctly if another malfunction occurs.
TIP
The ABS performs a self-diagnosis test for a few seconds each time the vehicle first starts off after the
main switch was turned to "ON". During this test, a "clicking" noise can be heard from under the seat,
and if the brake lever or brake pedal are even slightly applied, a vibration can be felt at the lever and
pedal, but these do not indicate a malfunction.
Self-diagnosis using the ABS ECU
The ABS ECU performs a static check of the entire system when the main switch is turned to "ON". It also
checks for malfunctions while the vehicle is ridden. Since all malfunctions are recorded after they are
detected, it is possible to check the recorded malfunction data by utilizing the Yamaha diagnostic tool when
the ABS ECU has entered the self-diagnosis mode.
Special precautions for handling and servicing a vehicle equipped with ABS
ECA17620
NOTICE
Care should be taken not to damage components by subjecting them to shocks or pulling on
them with too much force since the ABS components are precisely adjusted.
• The ABS ECU and hydraulic unit are united assemblies and cannot be disassembled.
• The malfunction history is stored in the memory of the ABS ECU. Delete the fault codes when the ser-
vice is finished. (This is because the past fault codes will be displayed again if another malfunction
occurs.)
EAS30529
BASIC INSTRUCTIONS FOR TROUBLESHOOTING
EWA17420
WARNING
• Perform the troubleshooting [A][B][C] in order. Be sure to follow the order since a wrong
diagnosis could result if the steps are followed in a different order or omitted.
• Use sufficiently charged regular batteries only.
[A] Malfunction check using the ABS warning light
[B] Use the Yamaha diagnostic tool and determine the location of the malfunction and the cause from
the recorded fault code.
Determine the cause of the malfunction from the condition and place where the malfunction occurred.
[C] Servicing the ABS
Execute the final check after disassembly and assembly.
ABS (ANTI-LOCK BRAKE SYSTEM)
8-124