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Product: TRACK-TYPE TRACTOR
Model: D6T TRACK-TYPE TRACTOR LKJ
Configuration: D6T TRACK-TYPE TRACTOR XW, LGP Differential Steering LKJ00001-UP (MACHINE) POWERED BY C9 Engine
Troubleshooting
C7 and C9 Engines for Caterpillar Built Machines
Media Number -RENR9345-20 Publication Date -01/07/2015 Date Updated -08/07/2015
i02444803
Cat Data Link Circuit - Test
SMCS - 1901-038
System Operation Description:
Use this procedure to troubleshoot any suspect problems with the Cat Data Link.
Use this procedure to troubleshoot the system when one of the following diagnostic codes is active or
easily repeated:
• 296-09 Unable to communicate with Transmission ECM
• 296-12 Transmission ECM Failed
• 1639-09 Machine Security System Module not communicating on link
Note: This procedure checks for an open circuit or for a short circuit in the Cat Data Link. If you are
experiencing problems with communications between the Caterpillar Electronic Technician (ET) and
the Electronic Control Module (ECM), refer to the troubleshooting without a diagnostic code
procedure Troubleshooting, "Electronic Service Tool Will Not Communicate with ECM" before you
use this procedure.
The Cat Data Link is the standard Data Link that is used by the ECM to communicate with Cat ET.
The ECM communicates with Cat ET in order to share status information and diagnostic information.
Cat ET can also be used to configure the ECM parameters. This information will not be available if
communication fails between the ECM and Cat ET.
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Illustration 1 g01222915
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Schematic for the "Cat Data Link"
Test Step 1. Inspect the Electrical Connectors and the Wiring
A. Remove the electrical power from the ECM.
Illustration 2 g01167488
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Engine view (typical example)
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(1) J1/P1 connectors
B. Thoroughly inspect connector (1). Refer to the diagnostic functional test Troubleshooting,
"Electrical Connectors - Inspect".
Illustration 3 g01104274
P1 terminals that are associated with the "Cat Data Link"
(P1-8) Cat Data Link +
(P1-9) Cat Data Link −
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Illustration 4 g01222949
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Terminals that are associated with the "Cat Data Link" on the machine connector
(P1-40) Cat Data Link +
(P1-39) Cat Data Link −
C. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the "Cat Data
Link".
D. Check the allen head screw on each ECM connector for the proper torque. Also, check the allen
head screw on the customer connector for the proper torque. Refer to the diagnostic functional
test Troubleshooting, "Electrical Connectors - Inspect".
Expected Result:
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All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are
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free of corrosion, of abrasion, and of pinch points.
Results:
• OK - The harness and the connectors appear to be OK. Proceed to Test Step 2.
• Not OK - The connectors and/or the wiring are not OK.
Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Ensure that all of
the seals are properly in place and ensure that the connectors are completely coupled. Verify
that the original problem is resolved.
STOP
Test Step 2. Check for a Short Circuit
A. Disconnect the P1 ECM connector.
B. Disconnect Cat ET from the service tool connector.
C. Disconnect any other control modules from the "Cat Data Link". Refer to Illustration 1.
D. Measure the resistance between the points that are listed in Table 1. Be sure to wiggle the wires
in the harnesses as you make each resistance measurement.
Table 1
Resistance Measurements for the Cat Data Link
Connector and Terminal Terminal
All of the other terminals on the P1 connector
P1-8 (Cat Data Link +)
Ground stud
All of the other terminals on the P1 connector
P1-9 (Cat Data Link -)
Ground stud
Expected Result:
Each check of the resistance indicates an open circuit.
Results:
• OK - Each check of the resistance indicates an open circuit. Proceed to Test Step 3.
• Not OK - At least one check of the resistance does not indicate an open circuit. There is a short
circuit in the harness or in a connector.
Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Verify that the
original problem is resolved.
STOP
Test Step 3. Check for an Open Circuit
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A. Fabricate a jumper wire. Use the jumper wire in order to create a short circuit between
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terminals D (Cat Data Link +) and terminal E (Cat Data Link −) on the service tool connector.
B. Measure the resistance between P1-8 (Cat Data Link +) and P1-9 (Cat Data Link −).
C. Measure the resistance between the terminals at the connector for each control module that was
connected to the "Cat Data Link". Refer to Illustration 1.
Expected Result:
Each check of the resistance indicates a short circuit.
Results:
• OK - Each check of the resistance indicates a short circuit.
Repair: Perform the following procedure:
1. Connect the J1/P1 connectors. Connect Cat ET to the service tool connector.
2. Check the "Cat Data Link" for proper operation. If the data link does not operate
correctly, there may be a problem with the ECM.
Temporarily install a new ECM. Check the "Cat Data Link" again. If the new ECM
solves the problem, install the original ECM and verify that the original problem returns.
If the new ECM operates correctly and the original ECM does not operate correctly,
replace the original ECM. Verify that the problem is resolved.
STOP
• Not OK - At least one check of the resistance does not indicate a short circuit. There is an open
circuit or excessive resistance in the harness. There may be a problem with a connector.
Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Verify that the
original problem is resolved.
STOP
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