DRIVE GP-SWING 8U4978 - Caterpillar

Illustration 1 g00583168
System Schematic For AC Transformer Box + A Wye Connection Is Shown For The Generator.
When the engine-generator, or any source to which the engine-generator is synchronized to, is operating, voltages up to 600V are present in the control panel.Do not short these terminal with line voltage to ground with any part of the body or any conductive material. Loss of life or injury could result from electrical shock or injury from molten metal.
Test Step 1. THE PROBLEM IS WITH AC VOLTAGE OR THE PROBLEM IS WITH AC CURRENT.
Determine if the problem is with AC voltage or with AC current. Check the display of the GSC+ while the genset is running and the load is connected.Results:
AC VOLTAGE - Zero volts are showing on the display of the GSC+ for one or more AC phases. Proceed to Test Step 2.
AC CURRENT - Zero amperes are showing on the display of the GSC+ for one or more AC phases. Proceed to Test Step 7.Test Step 2. CHECK THE FUSES.
Check the three fuses on the AC transformer box + (ATB+).Expected Result:The fuses should not be open.Results:
OK - The fuses are not open. Proceed to Test Step 3.
NOT OK - One or more of the fuses are open.Repair: One or more of the fuses are open. Check for a shorted component or damaged wiring. Troubleshoot and repair the problem. See the Generator Set Wiring Diagram in Testing And Adjusting, "Schematics And Wiring Diagrams". After the problem has been repaired, replace the fuses. Stop.Test Step 3. CHECK THE GENERATOR OUTPUT.
Open the circuit breaker or remove the load.
Start the engine and run the genset.
Measure the voltage between all three fuses on the ATB+. Expected Result:The line to line voltage should measure the rated voltage of the genset. Results:
OK - The voltages are correct and the problem remains. Proceed to Test Step 4.
NOT OK - One or more of the voltages are NOT correct.Repair: The wiring or the connections are damaged. Check for damaged wiring between the ATB+ and the bus. See the Generator Set Wiring Diagram in Testing And Adjusting, "Schematics And Wiring Diagrams". Also, check the electrical connections at the terminal of the ATB+. See Testing And Adjusting, "Electrical Connector - Inspect". Stop.Test Step 4. CHECK THE CONNECTIONS
Shut down the engine.
Check the harness connector and the terminals of the ATB+.
Check the GSC+ harness connector. See Testing And Adjusting, "Electrical Connector - Inspect".
Check for one or more damaged wires between the ATB+ and the GSC+. See the Generator Set Wiring Diagram in Testing And Adjusting, "Schematics And Wiring Diagrams".Expected Result:The wiring and the connectors should have been good.Results:
OK - NO problem was found with the connectors or with the wiring. Proceed to Test Step 5.
NOT OK - The problem was with the connectors or with the wiring.Repair: Repair the connectors or replace the wiring harness. Stop.Test Step 5. CHECK THE OUTPUTS OF THE ATB+
Remove the GSC+ harness connector from the ATB+.
At the terminal of the ATB+, measure the resistance between the following terminals: terminal