Komatsu 830E-AC Shop Manual page 220

RELAY BOARDS
The auxiliary control cabinet contains eight relay
boards to provide control for many of the 24VDC cir-
cuits. Two types of boards are used. One type of
board contains circuit breakers in addition to 24VDC
relays and a PC board for special functions. The sec-
ond type of board contains relays only.
All relays are interchangeable. The circuit breakers
are interchangeable, providing that the circuit
breaker capacity is the same.
Do not interchange or replace any circuit breaker
with one of a different capacity than specified for
the circuit. Serious damage or a fire may result if
the wrong capacity breaker is used.
The relay boards are identified as follows:
• Relay Board 1 . . . . . . .Clearance/Turn Signal
• Relay Board 3 . . . . . . .Stop, Retard, Backup
. . . . . . . . . . . . . . .Lights
• Relay Board 4 . . . . . . .Parking Brake, Horn,
• Relay Board 5 . . . . . . .Head Lights
• Relay Board 6 . . . . . . .Backup Lights & Horn
. . . . . . . . . . . . . . .Engine Functions,
. . . . . . . . . . . . . . .Ether Start,
. . . . . . . . . . . . . . .5 Minute Idle System
• Relay Board 7 . . . . . . .Auto Lube System,
. . . . . . . . . . . . . . .Starter Failure System
. . . . . . . . . . . . . . .Bleeddown Relay
• Relay Board 8 . . . . . . .Mid/Full Load Signals
. . . . . . . . . . . . . . .Shutters,
. . . . . . . . . . . . . . .Load Light Power
. . . . . . . . . . . . . . .Red, Yellow & Green PLM
. . . . . . . . . . . . . . .Lights
• Relay Board 9 . . . . . . .Park Brake Off Signal,
. . . . . . . . . . . . . . .Engine Start
. . . . . . . . . . . . . . .Start Lockout
. . . . . . . . . . . . . . .Engine Start
Refer to Figure 3-1 for the location of each relay
board. Refer to the Circuit Breakers chart at the end
of this section for electrical circuit identification num-
bers.
D3-10
Body-up, Engine Cranking
24VDC Electrical System Components
Relay Boards RB1, RB3, RB4, RB5
Each relay board of this type is equipped with four
green lights (9, Figure 3-6) and one red "breaker
open" light (7). Each relay board has a fifth green (8)
light that has a different function on each board.
Four green lights (9) are labeled K1, K2, K3, or K4.
These lights will be on only when that particular con-
trol circuit has been switched ON and the relay coil is
being energized. The light will not turn on if the relay
board does not receive the 24 volt signal to turn on a
component.
If illuminated, red "breaker open" light (7) indicates
that a circuit breaker on that relay board is in the OFF
position. A light on the overhead display panel will
also illuminate, informing the operator that a circuit
breaker is in the OFF position. The red "breaker
open" light will turn ON whenever there is a voltage
difference across the two terminals of a circuit
breaker.
If a control switch has been turned ON and a green
(K) light is on, but that component is not operating,
check the following on the relay board for that circuit:
If a circuit breaker light is on, press all the
circuit breakers to make sure that they are
all on. There is no visual indication as to
which circuit breaker has been tripped.
Check the operation of the component. If it
trips again, check the wiring or component
for the cause of the overload.
The contacts inside the relay may not be
closing, or the contacts may be open,
preventing an electrical connection. Swap
relays and check again. Replace defective
relays. Relays may take one minute to trip
and 30 seconds before they can be reset.
Check the wiring and all of the connections
between the relay board and the
component for an open circuit.
The component may be defective. Replace
the component.
There is a poor ground at the component.
Repair the ground connection.
10/06 D03036