Preheating Circuit - Komatsu WA250-6 Shop Manual

920 Electrical system, Part 2

Preheating circuit

Preheating circuit

1. Battery
2. Battery relay
3. Slow-blow fuse
4. Fuse box 1
5. Starting switch
6. Engine controller
7. Machine monitor
8. Electrical intake air heater relay
9. Electrical intake air heater
10. Boost pressure and temperature sensor
Outline
The automatic preheating system is installed
q
so that the engine will start easily in a cold dis-
trict.
The automatic preheating system is capable of
q
cutting the preheating time short as the starting
switch is set to "ON". This system is also capa-
ble of automatically setting the preheating
duration referencing temperature of intake air.
Setting the starting switch to "ON" lights the
q
preheater pilot lamp of the machine monitor
and starts preheating of intake air with the
electrical intake air heater.
The engine controller sets the preheating dura-
tion referencing the intake air temperature
being sent from the boost pressure sensor and
temperature sensor.
The pilot lamp remains turned on as long as
q
preheating is continued. Keep the starting
switch in the "ON" position during this time.
Setting the starting switch to "START" from this
state resets preheating.
WA250, 250PZ-6
Operation
Set the starting switch to "ON" to start the
q
engine controller. At this time, if intake air tem-
perature is -4°C or below, the engine controller
starts up the electrical intake air heater imme-
diately after the starting switch is turned "ON"
to initiate preheating by the electrical intake air
heater.
The preheating time is set as shown below.
q
SEN03834-01
1
27
10-920