John Deere 6068HFG08 Engine

1. Turn the overfrequency adjustment potentiometer fully clockwise (CW).
2. Place master switch in RUN to start the generator set.
3. Adjust governor per engine operation manual, engine service manual, or governor section of this manual.
4. Slowly turn overfrequency potentiometer counterclockwise (CCW) until the LED starts flashing; after about 10 seconds the set shuts down on auxiliary fault.
5. Place master switch to OFF/RESET to reset the controller.
6. Place master switch to RUN to start the generator set.
7. Readjust the governor to the desired frequency as required.
8. Place master switch to OFF/RESET to stop the generator set.

⚠ Hazardous voltage. Moving parts. Will cause severe injury or death. Operate the generator set only when all guards and electrical enclosures are in place.

⚠ Disconnecting the electrical load. Hazardous voltage will cause severe injury or death.

1. Disconnect generator set from load by opening line circuit breaker or disconnecting and taping output leads.
2. Determine overvoltage shutdown value based on user requirement; factory setting is 15% above nominal line-to-neutral voltage.
3. Remove the controller cover.
4. Place master switch in RUN to start the generator set.
5. Observe AC voltmeter; turn voltage adjustment potentiometer CW until generator set shuts down.
6. If the shutdown point is correct, go to step 12; otherwise continue.
7. Turn controller circuit board R42 adjustment potentiometer fully CW.
8. Place master switch to OFF/RESET to reset; then to RUN to start.
9. Observe AC voltmeter while turning voltage adjustment potentiometer to desired overvoltage shutdown point.
10. Turn R42 adjustment potentiometer slowly CCW until the generator set shuts down.
11. Turn controller voltage adjustment potentiometer slightly CCW.
12. Place master switch OFF/RESET then RUN to start; adjust for correct voltage and phase.
13. Place master switch OFF/RESET to stop.
14. Disconnect battery negative lead first; reconnect generator set to load; reconnect battery negative lead last.

Tools: Voltmeter, Wattmeter

1. Remove any load; start each generator set with master switch in RUN.
2. Set reactive droop compensator rheostat on generator set no. 1 to minimum CCW; record rpm/frequency and voltage at 1/4 load steps to full load.
3. Repeat for generator set no. 2.
4. Compare readings; adjust voltage within 1 volt and speed within 3 rpm (or 0.1 Hz) at each load step.
5. Check droop compensation on each unit with an inductive load 1/2 to full load.
6. Adjust rheostat to approximately 4% below rated voltage at full load.
7. Repeat for unit no. 2.

Tools: Voltmeter

1. Turn reactive droop compensator rheostat on generator set no. 1 to minimum setting.
2. Remove controller cover; move voltage sensing lead from V7 to V9 at the AC fuse terminal block.
3. Remove any load connected to the generator set.
4. Start the generator set with master switch in RUN.
5. Use controller or remote voltage adjusting potentiometer to fine adjust voltage.
6. Apply resistive load (1.0 power factor) until reaching rated current.
7. Adjust reactive droop compensator rheostat to achieve a 4% droop in voltage.
8. Remove the resistive load and stop the generator set.
9. Return voltage sensing lead from V9 to V7 at the AC fuse terminal block.
10. Replace the controller cover and repeat for generator set no. 2.

1. Turn underfrequency adjustment potentiometer fully clockwise (CW).
2. Place master switch in RUN to start the generator set.
3. Adjust governor per engine operation manual, engine service manual, or governor section of this manual.
4. Slowly turn underfrequency potentiometer counterclockwise (CCW) until LED starts flashing; after about 10 seconds the set shuts down on auxiliary fault.
5. Place master switch to OFF/RESET to reset the controller.
6. Place master switch to RUN to start the generator set.
7. Readjust the governor to the desired frequency as required.
8. Place master switch to OFF/RESET to stop the generator set.

⚠ Hot engine and exhaust system can cause severe injury or death. Do not work on the generator set until it cools.

⚠ Hazardous voltage. Moving parts. Will cause severe injury or death. Operate the generator set only when all guards and electrical enclosures are in place.

Tools: DC voltmeter

1. Measure DC voltage between lead 31A (+) and ground (- ) with sender submerged in coolant; voltmeter indicates approximately 12.5 VDC.
2. Measure DC voltage between lead 31A (+) and ground (- ) with sender removed from coolant for at least 5-15 seconds; voltmeter indicates a drop to approximately 7 VDC.

⚠ Hot engine and exhaust system can cause severe injury or death. Do not work on the generator set until it cools.

⚠ Hazardous voltage. Moving parts. Will cause severe injury or death.

Tools: Ohmmeter

1. Measure resistance between lead 31 and ground with sender submerged in coolant; ohmmeter indicates a high resistance reading.
2. Measure resistance between lead 31 and ground with sender removed from coolant for at least 5-15 seconds; ohmmeter indicates a low resistance reading.

⚠ To prevent reverse polarity damage to the battery equalizer, remove the ground (GND) connection first and attach the ground connection last when disconnecting the battery equalizer.

Tools: 12-volt test light with alligator clips, Voltmeter with 0.01 volt resolution, Battery load tester

1. Remove the ground (GND) connections from the battery equalizer; do not allow contact with other connections.
2. Verify a differential of 12 volts between the +12 volt and +24 volt terminals using a 12-volt test light; the light will illuminate on a functional unit. Remove the test light.
3. Connect the test light between the +12 volt and GND terminals; the light will illuminate on a functional unit.
4. With the test light connected, measure and record the voltage between the +12 volt and +24 volt terminals.
5. With the test light connected, measure and record the voltage between the +12 volt and GND terminals.
6. Remove the test light.
7. Compare the values from steps 4 and 5; the difference should be - 0.5 and +0.13 volts on a functional unit.

Tools: Ohmmeter, Mechanical oil pressure gauge

1. Disconnect the oil pressure sender lead 7C.
2. Check the sender resistance with an ohmmeter.
3. Compare resistance values when the generator set is shut down and when running at operating temperature to Section 1, Specifications.
4. Use a mechanical oil pressure gauge to further verify correct readings.

1. On gas-fueled sets, disconnect the coil wire at the distributor cap and ground it or disconnect the ignition system.
2. On diesel-fueled sets, unplug the fuel injector harness from ECM or disconnect wire no. 70 from the injector pump solenoid.
3. Place unit in RUN mode; observe 15-second on-off cranking cycles and maximum 75-second elapsed time to overcrank shutdown.
4. Observe controller fault lamp and display for an overcrank shutdown.
5. Place unit in OFF/RESET mode.
6. Reconnect the ignition coil wire/ignition system, or reconnect the fuel injector harness/wire no. 70.

⚠ Keep leads connected to the speed sensor terminals during the test; do not disconnect the leads.

Tools: DC voltmeter

1. Connect a DC voltmeter between positive (+) lead (wire 24) at the speed sensor and ground (wire 2) with master switch OFF/RESET; read approximately 8- 12 volts DC.
2. Place master switch in RUN to start the generator set.
3. Connect DC voltmeter negative probe to 0 terminal (wire 16 white) and positive probe to positive (+) terminal (wire 24 red); read approximately 7- 12 volts DC.
4. Place master switch in OFF/RESET to stop the generator set.
5. If sensor emits a signal, check continuity of speed sensor leads (wires 2, 16, 24) between controller P1 connector and sensor terminals.

Tools: DC voltmeter, 12-volt battery or DC power supply, Flat piece of iron or steel

1. Place master switch in OFF/RESET position.
2. Disconnect the speed sensor leads.
3. Connect speed sensor, DC voltmeter, and DC voltage source as shown.
4. Touch sensing surface with a flat piece of iron or steel at least 4.1 cm (1/4 cu. in.) in size.
5. DC voltmeter reading should equal the source voltage, approximately 12 VDC.
6. Remove the iron or steel piece and observe a voltmeter reading of 0 VDC.
7. If the sensor passes, it is functional; replace if it fails.
8. Connect the speed sensor leads and adjust the air gap.