This dead bus sensor provides an additional indication of the state of the bus. The bus can be live or dead. The input of the dead bus sensor is compared to the reading of the bus voltage, and the diagnostics are produced if the measurements differ.
When the input of the dead bus sensor is inactive, the input will float to approximately 10.5 DCV. An inactive state indicates that the bus is live. When the input of the dead bus sensor is active, the bus will be dead.
The possible cause of a CID 1168 FMI 04 is a short from the input signal of the dead bus sensor to negative battery terminal ("BATT-").
A CID 1168 FMI 04 is detected under the following condition.
- The voltage of the Phase A of the bus is greater than 50% of the rated voltage and the input of the dead bus sensor is floating. The voltage of the Phase A is determined by the "BTB+" input to the GSC+P.
The GSC+P treats a CID 1168 FMI 04 as an alarm fault. The dead bus paralleling function will be stopped when this diagnostic code is detected. No other synchronization processes will be affected.
Test Step 1. CHECK THE INACTIVE VOLTAGE LEVEL OF THE INPUT OF THE DEAD BUS SENSOR .
- Turn the Engine Control Switch (ECS) to STOP.
- Locate the wire that is connecting pin 29 of the GSC+P to terminal "DBR-9" of the Dead Bus Relay (DBR). Remove this wire at terminal "DBR-9" of the DBR only. Pin 29 of GSC+P will remain connected to the wire.
- Use a cable probe to measure the voltage at pin 29 of the GSC+P.
Expected Result:
The voltage should measure 10.5 ± 1.0 DCV.
Results:
- OK - The voltage level is 10.5± 1.0 DCV. Proceed to Test Step 2.
- NOT OK - The voltage level is not within the correct range.
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 problem remains, replace the GSC+P. Refer to Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace".
STOP
Test Step 2. CHECK THE FUNCTION OF THE BUS RELAY.
- Reconnect the wire that is connecting pin 29 of the GSC+P to terminal "DBR-9" of the DBR.
- Use a cable probe to monitor the voltage on pin 29 of the GSC+P.
- Ensure that the bus is dead, or carefully disconnect power from the relay coil of the DBR.
Expected Result:
The voltage of pin 29 of the GSC+P should measure 0.0 ± 0.5 DCV.
Results:
- OK - The voltage is 0.0 ± 0.5 DCV. Proceed to Test Step 3.
- NOT OK - The voltage is incorrect.
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 problem remains, replace the GSC+P. Refer to Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace".
STOP
Test Step 3. CHECK THE FUNCTION OF THE BUS RELAY.
- Carefully reconnect any power wires of the DBR that may have previously been removed.
- Ensure that the bus is live.
- Use a cable probe to measure the voltage at pin 29 of the GSC+P.
Expected Result:
The voltage should measure 10.5 ± 1.0 DCV.
Results:
- OK - The voltage is 10.5 ± 1.0 DCV.
Repair: The GSC+P is functioning properly. The problem is in the wiring or the component that is connected to the input of the dead bus sensor of the GSC+P. Use the FMI information and the Dead Bus Sensor input System Schematic to find the exact cause of the diagnostic code.
STOP
- NOT OK - The voltage is incorrect.
Repair: The GSC+P has failed. Replace the GSC+P. Refer to Testing and Adjusting, "EMPC Electronic Control (Generator Set) - Replace".
STOP