Jacobsen Eclipse 322, Repair Manual

Page: 149 / 336

ELECTRICAL
4222983 Second Edition 4-75
4
Fault: Engine RPM Fluctuates (Hunting) –
Gas and Diesel Hybrid Units Only
1. Fault: Under stable loads, engine behaves erratically
with engine RPM changes from Low-High and
High-Low. Traction speed does not fluctuate.
2. Possible root cause(s) and troubleshooting
procedure:
a. Fuel filter or system clogged.
b. Generator Control Unit (GCU) is reacting to
abrupt changes in system voltage.
i. Visually inspect buffer batteries and cables
for proper torque or damaged terminals.
Check condition of buffer batteries.
ii. Visually inspect PDU studs 1 and 3 and
switched contactor terminals for proper
torque. Refer to service manual.
iii. Visually inspect connections for proper
torque in rectifier box on generator.
c. Faulty throttle actuator or connection (Unlikely)
i. Visually inspect throttle actuator for
damaged wires or loose connections and
damaged or loose mechanical linkage.
ii. Verify proper operation of actuator linkage.
iii. Measure voltage approximately 8VDC with
no load between J38-pin1 and J38-pin2.
d. Faulty GCU or connectors
i. Visually inspect GCU and connectors for
damaged wires or loose connections.
ii. Measure voltage approximately 8VDC
between J36-pinH1 and J36-pinH2.
3. Fixes:
a. For issue 2.a: Verify proper operation of fuel
system. Replace fuel filter.
b. For issue 2.b: Tighten connections to 80 lb-in. (9
N·m).
c. For issue 2.c.i: Repair damaged wires or
connectors.
d. For issue 2.c.ii: If voltage is 8VDC and engine
still hunts, replace throttle actuator. If issue is
corrected, reinstall old throttle actuator to verify
fault returns. If voltage is not steady, go to 2.d.
e. For issue 2.d.i: Repair damaged wires or
connectors.
f. For issue 2.d.ii: If voltage is 8VDC and engine
still hunts, replace generator harness. If voltage
is not steady and both of the following readings
are correct, check generator coupler. Replace
GCU. If issue is corrected, reinstall old GCU to
verify fault returns.
i. Measure continuity: DMV-Ohms should be
less than 0.5 Ohms and no crossover
between J35-pinC1 and J37-pin1 and
J35-pinC2 and J37-pin8.
ii. Measure continuity: DMV-Ohms should be
less than 0.5 Ohms and no crossover
between J35-pinA1 and J37-pin4.
4. If unit still does not operate after performing all the
above procedures, please contact Technical Support
immediately.
Fault: Engine RPM Does Not Increase With
Load Changes – Gas and Diesel Hybrid
Units Only
1. Fault: Engine RPM stays constant (low idle) even
though load is increased.
2. Possible root cause(s) and troubleshooting
procedure:
a. Verify Voltage output on LDU.
b. Vehicle is in “Whisper” mode.
i. Visually inspect system power indicator
green LED is not flashing in LDU.
c. Faulty throttle actuator or connection
i. While turning key switch ON, verify throttle
actuator goes through full cycle by fully
extending and fully retracting. If not, visually
inspect throttle actuator for damaged wires,
loose connections or damaged, loose or
binding mechanical linkage.
d. Faulty GCU or connectors
i. Visually inspect GCU and connectors for
damaged wires or loose connections.
ii. Measure voltage approximately 8VDC
between J36-pinH1 and J36-pinH2.
3. Fixes:
a. For issue 2.b: Return vehicle to “Operating”
mode.
b. For issue 2.c: If throttle actuator does not cycle
and visual inspection of wires, connections and
linkages are correct, measure voltage
approximately 8VDC between J38-pin1 and
J38-pin2. If voltage is correct, replace throttle
actuator. If issue is corrected, reinstall old throttle
actuator to verify fault returns. If voltage is not
correct, go to step 2.d.
c. For issue 2.d.i: Repair damaged wires or
connectors.
d. For issue 2d.ii: If voltage is not 8VDC, replace
GCU. If issue is corrected, reinstall old GCU to
verify fault returns.
4. If unit still does not operate after performing all the
above procedures, please contact Technical Support
immediately.