C7.1 Marine Engine Caterpillar

This procedure tests that the correct voltage is being supplied to the Electronic Control Module (ECM).

This procedure covers the following codes:

Table 1

Diagnostic Trouble Codes
J1939 Code	Code Description	Comments
168-3	Battery Potential / Power Input #1 : Voltage Above Normal	The ECM detects voltage that is above the acceptable value.
168-4	Battery Potential / Power Input 1 : Voltage Below Normal	The ECM detects voltage that is below the acceptable value.
Follow the troubleshooting procedure in order to identify the root cause of the fault.

Illustration 1	g06081282
(1) 70 Way Connector

Illustration 2	g06081623
70 Way Connector

Table 2

Troubleshooting Test Steps	Value	Results
1. Determine the Diagnostic Code A. Establish communication between the electronic service tool 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 the electronic service tool. Wait at least 30 seconds so that any codes may become active.	Diagnostic code	Result: One of the diagnostic codes listed in Table 1 is active. Proceed to Test Step 2. Result: The electronic service tool will not communicate with the ECM. Repair: Refer to Troubleshooting, "Electronic Service Tool Does Not Communicate".
2. Check the Charging Circuit A. Check the charging circuit. Refer to Systems Operation, Testing and Adjusting, "Charging System - Test".	Charging circuit	Result: The charging system is OK. Proceed to Test Step 3. Result: The charging system is not OK. Repair: There is a fault in the charging system. Make the necessary repairs. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
3. Load Test the Batteries A. Use a suitable battery load tester to test the batteries. Refer to Systems Operation, Testing and Adjusting, "Battery - Test" for the correct procedure.	Load test	Result: The batteries pass the load test. Proceed to Test Step 4. Result: The batteries do not pass the load test. Repair: Recharge or replace the faulty batteries. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
4. Inspect Electrical Connectors and Wiring A. Ensure that the battery disconnect switch is in the CLOSED position. B. Thoroughly inspect all connectors associated with the electrical power supplies. C. Check all fuses. D. Perform a 45 N (10 lb) pull test on each of the wires in the connectors associated with the electrical power supplies. E. Check all of the wiring associated with the electrical power supplies for abrasions and pinch points. F. Verify that the "System Operating Voltage Configuration" is correctly configured in the Engine ECM configuration parameters.	Damaged wire or connector. Blown fuse.	Result: A damaged wire or damaged connector was found. A blown fuse was found. Repair: Repair the damaged wire or the damaged connector. Replace all blown fuses. Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault. Result: The "System Operating Voltage Configuration" is configured incorrectly. Repair: Program the parameter with the correct system voltage. Result: A damaged wire or damaged connector was not found. The fuses are OK. Contact the Dealer Solutions Network (DSN).

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).