BODY 2Y2173 - Caterpillar

Chassis ECM
The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the Cat data link of the machine.
Table 1
Chassis ECM (MID 87)
DTC Code Description System Response
248-9 CAT Data Link: Abnormal update rate Loss of CDL network between any controls. Used with companion code to indicate where failure occurred. Possible causes for an FMI 9 diagnostic code are:
The wrong software is installed on an ECM.
An improper key was used.
The ECM is operating intermittently.
Terminating resistors on the J1939 data link are faulty.
An open or a poor connection in the data link circuit.
There is a short in the data link circuit.
An ECM or smart device is not powering up or powering down properly.
Excessive noise on the data link circuit.
One of the ECMs or smart devices has failed. This condition is unlikely.
Illustration 1 g03201944
Schematic of the Cat Data Link
Note: The diagram above is a simplified schematic of the Chassis ECM and the Cat Data Link connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR1138 for the complete schematic.Diagnostic Trouble Code Procedure
Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. Check the wiring for pinch points or abrasions. Look for and repair areas that indicate wires are exposed. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing a troubleshooting procedure.
Table 2
Troubleshooting Test Steps Values Results
1. Identify The Active FMI Code Associated With The Data Link Code present FMI 9, proceed to Test Step 2.
2. Check For Other Codes
A. Check for similar diagnostic codes that are logged against other electronic control modules.
B. If a similar diagnostic code is found, exit this test and perform the corresponding procedure for the other diagnostic code that is shown.
Another diagnostic code is showing. OK - Exit this procedure and perform the diagnostic procedure for the diagnostic codes that are shown.
Proceed to Test Step 7.
NOT OK - There are no other related diagnostic codes.
Proceed to Test Step 3.
3. Inspect The Harness Connections
A. Turn key start switch and disconnect switch OFF.
B. Inspect all harness connections related to the CAT data link. Make sure that the connectors are clean and tight.
The machine harness is correct. OK - The machine harness is correct.
Proceed to Test Step 4.
NOT OK - The machine harness is not correct.
Repair: Repair or replace the machine harness.
Proceed to Test Step 7.
4. Check For A Short To Ground
A. Turn the keyswitch and the disconnect switch to the OFF position.
B. Disconnect the machine harness from all the electronic control modules that use the Cat data link.
C. At the machine harness for the ECM, measure the resistance between frame ground and connector contacts Cat Datalink (+) and Cat Datalink (-).
The resistance measurement should be greater