KIT- 4551108 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the power to the engine Electronic Control Module (ECM). Use this procedure if any of the diagnostic codes in Table 1 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 ECM detects voltage that is above the acceptable value.
168-4
Battery Potential / Power Input #1 : Voltage Below Normal 168-4
Electrical System Voltage : Voltage Below Normal The ECM detects voltage that is below the acceptable value. The engine ECM requires the keyswitch to be in the ON position in order to maintain communications with Cat® Electronic Technician (ET).Note: The DEF Quality Sensor is only available on 2017models or later.
Table 2
Troubleshooting Test Steps Values Results
1. Determine the Code
A. Establish communication between the Cat ET and the ECM . Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Start the engine. Run the engine until the engine is at normal operating temperature.
C. Observe the "Active Diagnostic" screen on Cat ET. Wait at least 30 seconds so that any codes may become active.
Codes
Result: A -3 or -11 diagnostic code is active.
Proceed to Test Step 2.
Result: A -4 diagnostic code is active.
Proceed to Test Step 3
2. Check the Charging Circuit
A. Check the charging circuit. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting".
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. Make the necessary repairs. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting".
If the problem is not resolved, proceed to Test Step 3.
3. Load Test the Battery
A. Load test the battery. Refer to Systems Operation and Testing and Adjusting, "Battery - Test"
Load Test
Result: The battery voltage is low or the battery did not pass the load test.
Repair: Recharge or replace the faulty batteries. Verify that the repair eliminates the problem.
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.
1. Verify that the "System Operating Voltage Configuration" is correctly configured in the Engine ECM configuration parameters.
2. Check the wiring between the batteries and the ECM. Refer to the application-specific Schematic for pin locations.
3. Check the connectors between the batteries and the ECM for moisture and/or corrosion.
Repair: Repair or replace the wiring and/or the connectors. Verify that the repair eliminates 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).