TP-5936 7/04 21Section 6 Controller Troubleshooting
6.3.2 High Water Temperature (HWT)
and High Exhaust Temperature
(HET) Shutdown Switch
When a high temperature is encountered at one (or
both) of these sources, the shutdown switch contacts
close and energize the K4 relay (LED4 lights).
The normally closed K4 contacts open to deenergize the
K25 relay. The K25 normally open contacts open to
deenergize the fuel solenoid.
The normally open K4 contacts close to maintain ground
to the K4 relay.
As the generator set shuts down, the K1 relay
deenergizes (LED1 goes out). The normally open K1
(A) contacts open to deenergize the K2 relay (LED2
goes out). The normally closed K2 contacts close to
ground circuit to the K4 relay until the generator set
comes to a complete stop.
6.3.3 Controller Circuit Board
Some controller circuit board components can be tested
without removing the component from the circuit board.
Perform these checks prior to installing a new circuit
board and attempting startup. Refer to Figure 6-3,
troubleshooting flow chart.
The controller circuit board has light-emitting diodes
(LEDs) which indicate relay coil power and aid in the
circuit board and the generator fault detection. When
any of relays K1--K5 receive power, the corresponding
LED lights. See Figure 6-2. The LED does not indicate
whether the relay coil is energized. Determine if the
relay coil is energized by analyzing the generator faults
by performing a continuity test on the relay coil.
H-239563-
Relay Schematic
14
5
678910
11
12
23
1. Engine crank control relay (K3)
2. P1 connector
3. P2 connector
4. Time delay relay (K5)
5. LED5
6. LED2
7. Engine run relay (K2)
8. AC crank disconnect relay (K1)
9. LED1
10. Fault shutdown relay (K4)
11. LED4
12. LED3
Figure 6-2 Controller Circuit Board
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