TP-6322 9/0420 Section 4 Troubleshooting
Engine Start Circuit Troubleshooting
1. Disconnect all power sources and wait at least five
minutes.
2. Manually operate contactor to the normal position.
3. Disconnect the exerciser switch wiring harness
from connector P2 on the controller assembly.
4. Remove the engine start wires from engine start
terminals ES3 and ES4 on TB3 on the controller
assembly. The engine should shut down after the
generator set’s time delay engine cooldown
(TDEC, if equipped) ends.
5. If the engine continues to run when it is not
supposed to, check for continuity on the engine
start wires. If there is continuity, a short in the wiring
leading to the generator set controller or a short on
the generator set controller or other generator set
problem could be causing the engine to run.
6. If the engine would not start when it was supposed
to, connect the engine start wires together. This
should signal the engine to start. If this doesn’t,
there could be an open circuit in the wiring leading
to the generator set controller, loose wires on the
generator set controller, or other generator set
problem.
7. Tape the ends of the engine start wires.
8. Check for continuity between terminals ES3 and
ES4 on TB3 on the controller assembly. The ES
LED should be off and the engine-start contact
should be closed. If not, check that jumper JP4 is
installed on the circuit board by checking for
continuity between terminals ES3 and ES3D on
TB3 on the controller assembly. If the jumper is not
in place, install a jumper wire between terminals
ES3 and ES3D on TB3. If the jumper is in place and
there is no continuity between terminals ES3 and
ES4, replace the controller assembly.
9. Apply the normal power source and wait for TDEC.
If the NA LED does not light, see Section 4.10. If
the NA LED lights and the ES LED does not light, or
the engine-start contact does not open within
±10% of the TDEC specification, replace the
controller assembly.
After completing troubleshooting in this section and the
ES LED correctly reflects the engine start circuit status:
D See Section 4.6 to troubleshoot engine starting
problems with the exerciser.
D See Section 4.8 to troubleshoot engine starting
problems in the automatic operation sequence.
Note: When engine start circuit troubleshooting is
complete, disconnect all power sources and
reconnect the exerciser switch wiring harness to
connector P2, and the engine start wires to
terminals ES3 and ES4 on TB3 on the controller
assembly.
4.6 Exerciser Circuits
Follow this section when:
D The plant exerciser does not start the engine at the
appropriate time when the exerciser switch is in the
Set or Enable position.
D The engine does not shut off when the exerciser
switch is in the Enable position after the exerciser
period ends.
D The engine does not shut off when the exerciser
switch is in the Disable position.
Within the exerciser switch there are two normally open
contacts which are both open when in the maintained
Enable position. When the switch is in the momentary
Set position, the c ontact from terminal COM to SET on
the main controller circuit board is closed. When the
switch is in the maintained Disable position, the contact
from terminal COM to DISABLE on the main controller
circuit board is closed. See Figure 4-4.
362140
112
111
110
3
SET
COM
DISABLE
J2--1 J2--2 J2--3
S1
21
P2--1 P2--3
P2
-- 2
MAIN CONTROLLER CIRCUIT BOARD
S1
1
2
3
112
111
110
ENABLE
J2
1
2
3
SET
DISABLE
(MOMENTARY)
Figure 4-4 Exercise Circuit
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