Enerpro Document No: OP-0116; Rev.
A
Page 2 of 3
ECO #19-11073; Release Date: 07/23/2019
Troubleshooting
1. General.
For any abnormal AuxGen issues on AC AuxGen locomotives, verify AuxGen AC
outputs. Measure the 3 AuxGen phase to phase AC voltages (AC1 to AC2, AC2 to AC3, and AC1
to AC3). If measurements are not equal, troubleshoot AuxGen.
2. Current Sensor Fault.
Current sensor fault is indicated by the Current Sensor Fault and Stage 3
LEDs being illuminated. RP voltage should be 72-72.8 VDC. If fuse CP1 is open, RP will read 0
VDC even with good output.
a.
Verify EBCS-3 current sensor wiring on back panel: white wire to Pin 3, red wire to Pin 9,
black wire to Pin 14.
b.
If wiring incorrect, correct per above, check fuse CP1, restart engine and re-evaluate
VR31.
c.
If wiring correct, check fuse CP1 and replace EBCS-3.
3. No LEDs and no Output.
Temporarily increase engine RPM. If VR31 begins operation as
indicated by Stage 1 LED illuminating, note idle RPM. If idle RPM is below normal range, correct
idle. If idle RPM is normal, replace VR31 with one that has the low-idle upgrade modification. The
low idle upgrade is identified by components R11 and R2 on the upper back of the circuit board.
On a standard VR31, R11 is light blue and RT2 is small. On a modified VR31, R11 is tan and
RT2 is larger as shown below.
Standard VR31
Low-Idle Upgrade VR31
Low-Idle Upgrade Marking
4. Tripped Circuit Breaker.
A tripped circuit breaker is caused by RP overvoltage or field over
current. An overvoltage may be caused by a locomotive wiring fault, excessive load dump, or a
faulty VR31. Shut down engine, reset circuit breaker and restart engine. If circuit breaker trips
again, verify back panel wiring AC1, AC2, and AC3 inputs. These inputs (pins 4, 6, and 10)
should only have the singe AC inputs connected. If back panel wiring is correct, remove and
replace VR31.
