
RENR9348-01 105
Troubleshooting Section
Test Step 2. Check for Active Diagnostic
Codes
A. Connect the Caterpillar Electronic Technician
(ET) to the service tool connector. Refer to
Troubleshoot
ing, “Electronic Service Tools”.
B. Turn the keyswitch to the ON position.
C. Observe the active diagnostic code screen on
Cat ET. Wait at least 15 seconds so that any
diagnostic c
odes may become active. Check for a
247-09 diagnostic code.
Expected Res
ult:
No diagnostic codes are active.
Results:
•
OK –Nocodesa
re active.
Repair: The problem may be intermittent. If the
problem is i
ntermittent, refer to Troubleshooting,
“Electrical Connectors - Inspect”.
STOP.
•
Not OK – A 247-09 diagnostic code is active.
Proceed to T
est Step 3.
Test Step 3. Verify the Proper Installation
of the CAN Data Link
A. Disconnect the J1939 display.
B. Disconnec
t the P1 connector and measure the
resistance between terminals P1-50 (CAN data
link +) and P1-34 (CAN data link -).
Expected Result:
The resist
ance is between 57 and 63 Ohms.
Results:
•
OK – The resistance is between 57 and 63 Ohms.
Proceed to Test Step 6.
•
Not OK – The resistance is between 114 Ohms
and 126 Ohms. A terminating resistor is missing.
Repair: Verify that two terminating resistors exist
on the data link. One resistor must be located on
each end o
f the data link. The engine is shipped
with one terminating resistor that is installed
between the ECM and the customer connector.
Refer to the appropriate electrical schematic in
order to determ
ine the missing resistor. Replace
the missing resistor. Verify that the problem is
resolved.
STOP.
•
Not OK – The res
istance is less than 57 Ohms.
ProceedtoTestStep4.
•
Not OK – The res
istance is greater than 126
Ohms. Proceed to Test Step 5.
Test Step 4. C
heck for a Short Circuit
A. Disconnect the J1/P1 ECM connector.
B. Remove the terminating resistors from the CAN
data link.
C. If a J1939 display is installed, disconnect the
display.
D. Measure the resistance between the points that
are listed in Table 18. Be sure to wiggle the wires
in the harne
sses as you make each resistance
measurement.
Table 18
Resistance Measurements for the CAN Data Link
Connector and
Terminal
Terminal
All of the other terminals on
the P1 connector
P1-50(CANdatalink+)
Engine ground
All of the other terminals on
the P1 connector
P1-34(CANdatalink-)
Engine gro
und
Expected R
esult:
Each check of the resistance indicates an open
circuit.
Results:
•
OK – Each check of the resistance indicates an
open circuit. Proceed to Test Step 5.
•
Not OK – At least one check of the resistance
does not indicate an open circuit. There is a short
circuit i
n a harness. There may be a problem with
a connector.
Repair: R
epair the wiring and/or the connector .
Replace part, if necessary. Verify that the problem
is resolved.
STOP.