770G and 772G Off-Highway Truck/Tractors Caterpillar

CAN Data Link - Test

Usage:

770G ECM

Chassis ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the CAN datalink of the machine.

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Table 1
Chassis ECM (MID 87)
DTC	Code Description	System Response
247-9	SAE J1939 Data Link: Abnormal update rate	Communication loss between engine and chassis control only. The only companion code supported is the engine control. Transmission shifting will be harsher. A level 2 code will be generated after a 6 second delay.
533-9	Brake Control: Abnormal update rate	Companion code for 248-9. With loss of CDL network, park brake status cannot be communicated. Park brake will remain in previous state. Compression brake outputs are disabled. Level 1 code after 30 seconds.
533-14	Brake Control: Special Instruction	Brake control will have reduced functionality. Compression brake outputs are disabled. Level 1 diagnostic after 5 seconds.
590-9	Engine Electronic Control Module: Abnormal update rate	Controlled throttle shifting (CTS) is disabled, throttle lock is disabled, speed limit is disabled, and auto lube solenoid is de-energized if it was energized.
590-14	Engine Electronic Control Module: Special Instruction	Unavailable parameters will show with "*****" in Messenger/Advisor and as unavailable in ET.
800-9	VIMS Main Module: Abnormal update rate	VIMS parameters will be flagged as Invalid, and VIMS functions (snapshots, datalogger, event chronological list) will not work.
800-14	VIMS Main Module: Special Instruction	VIMS parameters will be flagged as Invalid, and VIMS functions (snapshots, datalogger, event chronological list) will not work.
967-9	Machine Application Abnormal Update: Abnormal update rate	The machine system will use the last good product ID. If no known product ID, system will default to driving no outputs. Starter will not crank.
1089-9	VIMS Analysis Control Module: Abnormal update rate	Payload system will not operate.
1089-14	VIMS Analysis Control Module: Special Instruction	Reduced Machine Functionality.
1960-9	Key Reader: Abnormal update rate	MSS will never be installed in the factory, so this CID can be removed.
2448-9	Graphic Display Module: Abnormal update rate	Information may show as "*****" on display if the parameters are not known.
2448-14	Graphic Display Module: Special Instruction	No system response to this DTC.

Possible causes for an FMI 9 diagnostic code are:

Terminating resistors on the J1939 Data Link are faulty.
An open or a poor connection in the circuit.
A short in the circuit.
An ECM or smart device is not powering up or powering down properly.
Lack of key switch input to an ECM or smart device.
Excessive noise on the circuit.
Software configuration mismatch.
One of the ECM modules has failed. This condition is unlikely.

Possible causes for an FMI 14 diagnostic code are:

Incorrect software is installed.
Incompatible software may be installed.
Interference across the data link wires.
A control module has failed. This situation is unlikely.

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Illustration 1	g03433898
Schematic of the CAN Datalink

Note: The diagram above is a simplified schematic of the CAN Datalink 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.

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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. FMI 14, proceed to Test Step 7.
Begin Process For FMI 9 Troubleshooting HERE
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 8. 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 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 8.
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 CAN data link. C. At the machine harness for the ECM, measure the resistance between frame ground and connector contacts CAN Datalink (+) and CAN Datalink (-).	The resistance measurement should be greater than 5k Ω.	OK - The resistance is greater than 5k Ω. The harness circuit resistance is correct. Proceed to Test Step 5. NOT OK - The resistance is less than 5k Ω. Repair: Repair or replace the machine harness. Proceed to Test Step 8.
5. Check For A Short To Battery A. Turn the keyswitch and the disconnect switch to the OFF position. B. All related control modules remain disconnected from the machine harness. C. At the machine harness for the ECM, measure the resistance between (+) battery and connector contacts CAN Datalink (+) and CAN Datalink (-).	The resistance measurement should be greater than 5k Ω.	OK - The resistance is greater than 5k Ω. The harness circuit resistance is correct. Proceed to Test Step 6. NOT OK - The resistance is less than 5k Ω. Repair: Repair or replace the machine harness. Proceed to Test Step 8.
6. Check For An Open Harness A. The key start switch and disconnect switch remain OFF. B. All related control modules remain disconnected from the machine harness. C. Check the continuity of the CAN datalink circuit in the machine harness. D. At the machine harness for the ECM, measure the resistance between the connector contacts CAN Datalink (+) and CAN Datalink (-).	The reading is less than 5 Ω.	OK - The reading is less than 5 Ω. Proceed to Test Step 8. NOT OK - The resistance is greater than 5 Ω. Repair: Repair or replace the machine harness. Proceed to Test Step 8.
Begin Process For FMI 14 Troubleshooting HERE
7. Check For Proper Software Versions A. Use the Caterpillar Electronic Technician (Cat ET) service tool in order to verify that the versions of software are compatible.	The proper versions of software are installed.	OK - The versions of software are compatible. Proceed to Test Step 8. NOT OK - The proper software is not installed. Repair: Flash the proper software to the appropriate ECM. Cycle the keyswitch in order to initialize the new software. Ensure that the diagnostic code is no longer active. Proceed to Test Step 8.
8. Check If The Diagnostic Code Remains A. Inspect the harness connectors and clean the contacts of the harness connectors. B. Reconnect all harness connectors. C. Turn key switch and disconnect switch ON. D. Operate the machine. E. Check if diagnostic code is active.	Diagnostic code is no longer present.	OK - Diagnostic code does not exist at this time. Initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation. STOP NOT OK - Diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement. Prior to replacing this component, always contact the Technical Communication at your dealership for possible consultation with Caterpillar. This consultation may greatly effect repair time. Follow the steps in Troubleshooting, "Electronic Control Module (ECM) - Replace" if the ECM needs to be replaced. STOP