Yanmar 4BY - Replacing Engine Control Unit (ECU); Replace Coolant Temperature Sensor

ELECTRICAL AND ECU
BY Service Manual
12-25
Repair
REPAIR
Replacing Engine Control Unit (ECU)
IMPORTANT
The ECU may be damaged if it is powered
when you unplug it. Turn the key switch OFF
and disconnect the battery before
disconnecting the ECU from the electrical
harness.
1. Disconnect the electrical panel power cables
from the battery, negative (-) cable first.
2. Remove the electrical panel cover.
Figure 12-23
3. Disconnect two electrical connectors
(Figure 12-23, (1)) from ECU.
4. Remove screws securing the upper ECU
retainer (Figure 12-23, (2)).
5. Loosen the lower attaching screws
(Figure 12-23, (3)) and remove the ECU.
6. Install the new control unit and tighten the
screws.
7. Connect the electrical connectors to the ECU.
8. Connect the electrical panel power cables to
the battery
9. Check and delete any trouble codes that are
registered in the ECU after the work has been
completed.
Replacing Coolant Temperature
Sensor
1. Drain engine coolant.
2. Remove intake manifold.
Figure 12-24
3. Remove electrical connector
(Figure 12-24, (1)) from sensor.
4. Remove sensor (Figure 12-24, (2)) from
cylinder head.
5. Installation is in reverse of removal.
6. Tighten sensor to 13.4 N·m (119 in.-lb)
7. Check and delete any trouble codes that are
registered in the ECU after the work has been
completed.
(
1
)
(
2
)
(
3
)
0003799
000
3767A
(
1
)
(
2
)