3512C Engines for 785C Off-Highway Trucks with Dynamic Gas Blending Caterpillar

Use this procedure to troubleshoot a problem with the power to the engines Electronic Control Module (ECM). Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

Table 1

J1939 Code and Description	CDL Code and Description	Comments
168-3 Battery Potential / Power Input #1 : Voltage Above Normal	168-3 Electrical System Voltage : Voltage Above Normal	The battery supply voltage is less than 18 VDC on 24 VDC systems for 0.5 seconds or the battery supply voltage is less than 9 VDC on 12 VDC systems for 0.5 second. The engine ECM has been powered for 3 seconds. The engine is running for at least 3 seconds.
168-4 Battery Potential / Power Input #1 : Voltage Below Normal	168-4 Electrical System Voltage : Voltage Below Normal	The 24 VDC voltage falls below 18 VDC for .5 seconds. The 24 VDC voltage must return above 18.2 VDC for 3 seconds in order for the diagnostic to reset. The engine is running for at least 3 seconds.

Table 2

Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat® Electronic Technician (ET) to the service tool connector. B. Determine if a code is active or logged.	Codes	Result: A -3 code is active or logged. Proceed to Test Step 2. Result: A -4 code is active or logged. Proceed to Test Step 3.
2. Check the Charging Circuit	Charging Circuit	Result: The charging system is OK. Proceed to Test Step 3. Result: The charging system is NOT OK. Repair: There is a problem with the charging system. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting" for additional information. Verify that the repair eliminated the problem.
3. Inspect the Batteries A. Charge the batteries, if necessary. Refer to Special Instruction, SEHS7633, "Battery Test Procedure" for additional information. B. Load-test the batteries. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6, 8 V and 12 V Lead Acid Batteries" for additional information.	Batteries	Result: The batteries pass the load test. The measured voltage is between 11.5 VDC and 13.5 VDC for a 12 V system. The measured voltage is between 23.0 VDC and 27.0 VDC for a 24 V system. Repair: Verify that the "System Operating Voltage Configuration" is correctly configured in the Engine ECM configuration parameters. Verify that the repair eliminated the problem. Result: The battery voltage is low or the battery did not pass the load test. Repair: Repair or replace the batteries. Verify that the repair eliminated the problem.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).