
120 RENR9348-01
Troubleshooting Section
Expected Result:
No intermittent problems were indicated during the
“Wiggle Test”.
Results:
•
OK –Nointermi
ttent problems were found. The
harness and connectors appear to be OK. If you
were sent from another procedure, return to the
procedure and
continue testing. If this test has
resolved the problem, return the engine to service.
STOP.
•
Not OK – At least one intermittent problem was
indicated.
Repair: Repair the harness or the connector. Verify
that the repair eliminates the problem.
STOP.
i02412583
Electrical Power Su pp ly Circuit
-Test
SMCS Code: 1401-038
System Oper
ation Description:
Use this procedure to troubleshoot any suspect
problems wi
th the electrical power supply.
This procedure covers the following diagnostic codes:
•
168-00 System Voltage High
•
168-01 Syst
em Voltage Low
•
168-02 System V oltage intermittent/erratic
This procedure tests whether proper voltage is being
supplied to the Electronic Control Module (ECM).
The ECM is continuously powered with +Battery
voltage that is supplied to inputs P1-48, P1-52,
P1-53, P1-
55, and P1-57 and P1-70 (keyswitch). If
an emergency stop condition is initiated, the ECM
relay will be energized and battery voltage will be
removed fr
om the ECM.
Power to the ECM is provided by a set of normally
closed contact
s that are in ECM relay. The ECM relay
is controlled by a set of normally open contacts in the
emergency stop switch. When the emergency stop
switch is plac
ed in the STOP position, the contacts in
the emergency stop switch are closed and +24 VDC
is supplied to the control circuit for the ECM relay.
This opens th
e contacts in the relay and power is
removed from the ECM.
Opening the b
attery disconnect switch will also
remove power from the ECM. When the battery
disconnect switch is placed in the OFF position, the
ground conn
ection to inputs P1-61, P1-63, P1-65,
P1-67, and P1-69 of the ECM is removed.
During an en
gine start sequence, the Starting Motor
Magnetic Switch (SMMS) is used by the ECM to
engage the starting motor. Voltage for the control
solenoid fo
r the SMMS is supplied by the ECM.
When the ECM supplies the signal, the SMMS is
energized. This powers the starting solenoid and the
starter is
engaged. Refer to the diagnostic functional
test Troubleshooting, “Start Relay Circuit - Test” for
information that is related to troubleshooting the
circuit f
or the SMMS.
Circuit protection is provided by circuit breakers for
the ECM re
lay, the SMMS, and the emergency stop
switch.