Replacing The Ecu (Engine Control Unit); Checking And Charging The Battery; Checking The Relays - Yamaha MT-09 2021 Service Manual

ECA27250
NOTICE
• Be careful not to lose or damage the fuse
box cover. If the fuse box cover is lost or
damaged, replace it with a new one.
• Be sure to install the fuse box cover. Water
may get inside the fuse box and cause mal-
function.
EAS31006

REPLACING THE ECU (Engine Control Unit)

1. Turn the main switch to "OFF".
2. Replace the ECU (Engine Control Unit).
TIP
Fix the ECU "1" with the claw of air filter case
cover "2" properly.
2
1
3. Clean the throttle bodies and reset the ISC
(idle speed control) learning value.
Refer to "CHECKING AND CLEANING THE
THROTTLE BODIES" on page 7-7.
4. Check:
• Engine idling speed
Start the engine, warm it up, and then mea-
sure the engine idling speed.
Engine idling speed
1200–1400 r/min
EAS30552

CHECKING AND CHARGING THE BATTERY

TIP
Refer to "CHECKING AND CHARGING THE
BATTERY" in "BASIC INFORMATION" (sepa-
rate volume).
1. Remove:
• Rider seat
Refer to "GENERAL CHASSIS (1)" on
page 4-1.
2. Disconnect:
• Battery lead
(from the battery terminals)
ELECTRICAL COMPONENTS
ECA13700
NOTICE
First, disconnect the negative battery lead,
and then the positive battery lead.
3. Remove:
• Battery
Refer to "GENERAL CHASSIS (1)" on
page 4-1.
4. Check:
• Battery charge
5. Charge:
• Battery
6. Install:
• Battery
Refer to "GENERAL CHASSIS (1)" on
page 4-1.
7. Connect:
• Battery lead
(to the battery terminals)
ECA26980
NOTICE
First, connect the positive battery lead, and
then the negative battery lead.
8. Check:
• Battery terminal
Dirt → Clean with a wire brush.
Loose connection → Connect properly.
9. Lubricate:
• Battery terminal
Recommended lubricant
Dielectric grease
10.Install:
• Rider seat
Refer to "GENERAL CHASSIS (1)" on
page 4-1.
EAS30553

CHECKING THE RELAYS

Check each switch for continuity with the digital
circuit tester. If the continuity reading is incor-
rect, replace the relay.
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with ta-
chometer
YU-A1927
1. Disconnect the relay from the wire harness.
8-56