
102 RENR9348-01
Troubleshooting Section
•
Not OK – The voltage is not 24 ± 3 VDC when
the engine spee
d increases above 75 percent of
the rated engine speed. The secondary output of
the air shutoff relay is not supplying the correct
voltage. Ther
emaybeaproblemwiththerelay.
Proceed to Test Step 10.
Test Step 10.
Check the Supply Voltage
to the Air Shu
toff Relay
A. Remove the wire from the supply to the secondary
circuitofth
e air shutoff relay.
B. Turn the battery disconnect switch to the ON
position.
C. Measure the voltage between the supply wire and
theengineg
round stud.
D. Turn the battery disconnect switch to the OFF
position.
Expected Result:
The voltage is 24 ± 3 VDC.
Results:
•
OK –Thevoltageis24±3VDC.
Repair: The air shutoff relay is not operating
correctly.
Theremaybeaprobleminthegroundcircuit
for the control input of the air shutoff relay. The
problem ma
y be with the air shutoff relay. Perform
the following procedure:
1. Remove the
ground wire from the air shutoff
relay.
2. Turn the ba
ttery disconnect switch to the ON
position.
3. Check the c
ontinuity of the ground circuit from
the relay to the battery.
If continu
ity exists in the ground circuit to the
air shutoff relay, the problem is with the air
shutoff relay. Replace the air shutoff relay.
If continuity does not e xist in the ground circuit
to the air shutoff relay, the problem is in the
ground ci
rcuit. Repair the circuit.
STOP.
•
Not OK – The voltage is not 24 ± 3 VDC .
Repair: The problem is in the supply circuit to the
air shutoff rel
ay. Ensure that the circuit breaker for
the air shutoff relay has not tripped. Repair the
circuit. Replace parts, if necessary. Verify that the
repair resolv
ed the original problem.
STOP.
i02421280
CAN Data Link Circuit - Test
SMCS Code: 1901-038
System Operat
ion Description:
The CAN data link is used to communicate
information
between the Electronic Control Module
(ECM) and other modules. Use this procedure to
troubleshoot any suspect problems with the CAN
data link.
This procedure covers the 247-09 J1939 Data Link
communicat
ions.
This procedure identifies the following problems:
•
Faulty connectors
•
Missing ter
mination resistors
•
Short circuits
•
Open circuits
•
Faulty J193
9 display