Yamaha F400A 2022 - Engine Control Unit and Component; Checking the Main Relay; Checking the Engine ECM Circuit

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Engine control unit and component
Engine control unit and
component
Checking the main relay
The main relay cannot be removed for testing
or replaced as a single unit because it is a
component part of the electrical management
box.
1. Check:
•Main relay
a. Connect the YDIS to display “Main re-
lay”.
b. Turn the main switch or power switch
to ON, and then check that “ON” is dis-
played for the main relay on the YDIS
screen.
c. Measure the input voltage between the
main fuse “a” and ground.
d. Turn the main switch or power switch
to OFF.
e. Install the fuse cover.
Checking the engine ECM circuit
1. Check:
•Engine ECM
a. Disconnect the engine ECM couplers
“a” and “b”.
b. Check the wire harness for continuity.
Continuity between the engine ECM
coupler “b” and ground:
c. Measure the input voltage between the
terminal 26 of engine ECM coupler “a”
and ground.
d. Turn the main switch or power switch
to ON, and then measure the input volt-
age between the terminal 36 of engine
ECM coupler “b” and ground.
Input voltage
12 V
Main fuse “a”–Ground
a
a b
Terminal of coupler
“b”
4 – Ground
5 – Ground
6 – Ground
7 – Ground
Input voltage
12 V
Terminal 26 of engine ECM cou-
pler “a”–Ground
7 6 5 4
b
<B>
26
a
<A>