The Bus Transformer Box (BTB +) reduces the AC line to neutral voltages of phase A and phase C from the bus to usable signal levels for the GSC+P. The GSC+P uses these reduced signals for detecting the phase sequence of the bus. The GSC+P will utilize the signal of phase A in order to measure the amplitude of the voltage on the bus. The GSC+P will utilize the signal of phase C in order to measure the frequency of the voltage on the bus.
The possible cause of CID 1170 FMI 04 diagnostic code is an open neutral connection to the input of the BTB +. An open neutral will cause a phase angle of approximately 180°.
Test Step 1. CHECK THE VOLTAGE OF THE INPUTS TO THE BUS TRANSFORMER BOX (BTB +)
- Turn the Engine Control Switch (ECS) to "STOP".
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| Illustration 1 | g00603288 |
Bus transformer box | |
- Locate the input wires of the BTB +.
- Start the engine and run the engine at rated speed.
- Close the breaker in order to energize the bus.
- Measure the voltage from phase A to the neutral lead. Also, measure the voltage from phase C to the neutral lead. Record the voltage readings.
- Measure the voltage from Phase A to Phase B.
- Compare the voltages measured in the previous two steps.
Expected Result:
The voltage measured from Phase A and Phase C to the neutral lead should be greater than 55% to 60% of the voltage measured from Phase A to Phase B.
Results:
- OK - The voltage measured from Phase A and Phase C to the neutral lead is greater than 55% to 60% of the voltage measured from Phase A to Phase B. Proceed to Test Step 2.
- NOT OK - The voltage measured from Phase A and Phase C to the neutral lead is NOT greater than 55% to 60% of the voltage measured from Phase A to Phase B.
Repair: The neutral wire is open. Use the System Schematic for the BTB + and the AC schematic in Testing And Adjusting, "Schematics And Wiring Diagrams" section to troubleshoot the wiring and find the exact cause of the diagnostic code.
STOP
Test Step 2. CHECK VOLTAGE ON GSC+P INPUT.
- Stop the engine. Turn the ECS to "STOP".
- Install cable probes on the GSC+P 40-pin connector pins 17 and 18.
- Start the engine and run the engine at rated speed.
- Close the breaker in order to energize the bus.
- On the GSC+P, measure the voltage from connector pin 17 to the negative battery terminal, and from connector pin 18 to the negative battery terminal. Record the voltage measurements.
- Measure the voltage between the GSC+P connector pin 17 and the GSC+P connector pin 18. Record the voltage measurements.
- Compare the voltages measurements with the voltage measurements recorded from the previous two steps.
Expected Result:
The voltage measured from pin 17 and 18 to the negative battery terminal should be greater than 55% to 60% of the voltage measured between pin 17 and pin 18.
Results:
- OK - The voltage measured from pin 17 and pin 18 to battery negative is greater than 55% to 60% of the voltage measured between pin 17 and pin 18. The GSC+P may have failed.
Repair: The GSC+P may have failed. It is unlikely that the GSC+P has failed. Exit this procedure and perform this entire procedure again. If the cause of the problem is the same, replace the GSC+P. Refer toTesting and Adjusting, "EMPC Electronic Control (Generator Set) - Replace".
STOP
- NOT OK - The voltage measured from pin 17 and 18 to the negative battery terminal is NOT greater than 55% to 60% of the voltage measured between pin 17 and pin 18.
Repair: The AC ground wire is open between the BTB+ and the GSC+P, or the jumper between terminals "B21" and "B22" on the BTB+ is broken or damaged. Repair the wire or replace the wire. Use the System Schematic for the BTB + and the AC schematic in to troubleshoot the wiring and find the exact cause of the diagnostic code. Refer to Testing And Adjusting, "Schematics And Wiring Diagrams". If none of these repairs corrects the problem, replace the BTB +. Refer to Testing and Adjusting, "EMPC Electronic Control (Bus Transformer Box) - Replace".
STOP