Yamaha XP500 Service Manual page 303

• [C-3] ABS warning light flashes
With the engine off, check the front and rear brake switches.
Check if the brake light comes on when the front or rear brake is applied.
1) The light does not come on for only one brake.
→ The corresponding brake switch connector is disconnected. (Refer to "CIRCUIT DIAGRAM".)
→ The corresponding brake switch is defective.
2) The light does not come on for either brake.
→ The wire harness (ABS system circuit) may be disconnected or the fuse may be blown. Check
the fuse and make sure the wire harness (ABS system circuit) (brown lead) is connected to the
power source end of the brake switch. (Refer to "CIRCUIT DIAGRAM".)
3) The brake light comes on.
→ The wire harness (ABS system circuit) couplers may be disconnected.
4) Adjust the rear brake switch to the specified setting.
• [C-4] ABS warning light flashes every 0.5 second
If the ABS warning light flashes every 0.5 second, the malfunction code of a past malfunction has
not been stored in the memory of the ECU (ABS). If a malfunction code is displayed on the multi-
function display, the ABS warning light flashes. Make sure that the customer understands the possi-
ble conditions when the ABS warning light comes on.
1. Warning light flashes
The following are probable causes to explain why the ABS warning light flashed while riding and
then stopped flashing or stopped flashing when the main switch was set to "OFF", then to "ON".
1) The rear wheel was rotated with the vehicle on the centerstand. → The system is normal.
2) The rear wheel raced. → The system is normal.
3) The vehicle was ridden on the rear wheel with the front wheel elevated. → The system is normal.
4) The vehicle was ridden on extremely uneven roads continuously. → The system is normal.
5) The brake switch is defective or improperly adjusted. → Replace or adjust.
2. Voltage drop
For the ABS to operate correctly, the voltage should be always higher than the specified voltage.
If the voltage drops to lower than 10 V, the ABS warning light comes on and the ABS does not
operate. When the voltage recovers to higher than 10 V, the ABS operates. However, the mag-
neto, battery and rectifier/regulator must be checked. Follow the regular procedures for service of
the power supply system.
3. ABS is stopped by the ECU (ABS)
The ECU (ABS) may stop the ABS operation if it is exposed to extremely strong electromagnetic
waves or static electricity.
When the ECU (ABS) is no longer exposed to the electromagnetic waves, static electricity, and
the ABS warning light is not flashing, there is no effect on the operation of the ABS. Explain to the
customer that the ABS will operate normally.
ANTI-LOCK BRAKE SYSTEM (XP500A)
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CHAS