Cummins/Onan DL6T Generator Set

1. Refer to the generator reconnection possibilities when changing voltage.
2. Reconnect lead W12 (inside control box) to the proper H terminal (H2, H3, H4, H5, or H6) depending on voltage selected.
3. Change jumper W12 from TB2-2 to the proper TB2 terminal.

Tools: voltmeter

1. Center the panel-mounted voltage adjustment knob vertically.
2. Start the set and allow it to stabilize at the correct frequency and speed.
3. Standard regulator: turn R18 counterclockwise to decrease voltage, clockwise to increase; set no-load voltage (e.g. 246 volts for 120/240 connection).
4. Standard regulator: turn R26 counterclockwise until voltage hunts, then clockwise until stable.
5. Switching regulator: turn R36 counterclockwise to increase voltage, clockwise to decrease; set no-load voltage.
6. Switching regulator: turn R5 counterclockwise until voltage hunts, then clockwise until stable.

Tools: DC ammeter, voltmeter

1. With engine running, check the battery charge rate DC ammeter; it should show a slight charge tapering to zero.
2. If constant discharge or constant high charge, stop set and check drive belt, terminal connections, and lead wires.
3. Use a voltmeter between output terminal and ground; nominal output should be 13.8 to 14.8 volts.
4. If output high (over 15 volts), check for loose or corroded voltage regulator leads; replace regulator if shorted.
5. If output low, problem could be worn/broken brushes, open regulator, or open field diode.

Tools: voltmeter

1. With the starter motor operating, check voltage drop from battery negative post to cylinder block.
2. Check voltage drop from battery positive post to battery terminal stud on the solenoid.
3. Normally each should be less than 0.3 volt.
4. Clean all connections in any part of the circuit showing excessive voltage drop.

1. To check energized-to-run operation, listen for a click in injection pump when start switch is placed in run position.
2. If no click and there is power to solenoid, the fuel solenoid must be replaced.
3. To check energized-to-stop operation, listen for a click when switch is placed in stop position.
4. If no click and there is no power to solenoid, the fuel solenoid must be replaced.

Tools: voltmeter, 12-volt source

1. Connect 12 volts across relay coil terminals; relay should activate if coil is okay.
2. Connect a 12-volt source to one side of relay contacts.
3. Connect a voltmeter to other side of relay contact and 12-volt source; 12 volts appear when relay energized indicates contact is okay.

Tools: voltmeter, jumper wire

1. Apply battery positive (B+) to the terminal marked S.
2. Jumper a ground wire to the solenoid mounting bracket; solenoid should activate.
3. If contacts are good, 12 volts should be read between terminal I and ground.
4. Voltage drop across the contacts should never exceed one volt in circuit application.

Tools: ohmmeter

1. Remove battery B+ cable.
2. Place ohmmeter leads across switch.
3. Open and close switch while observing ohmmeter.
4. A normally open (NO) switch should show infinite resistance open and continuity closed; NC is opposite.
5. Replace switch if defective.

Tools: ohmmeter

1. Remove reactor leads from terminal board for testing.
2. Measure resistance between coils 1-2 and 3-4; should be 0.031-0.37 and 0.037-0.46 ohms at 77 deg F (25 deg C).
3. Measure resistance between coils and from any terminal to frame; should be infinity.

Tools: Wheatstone Bridge, ohmmeter

1. Use a Wheatstone Bridge for this test.
2. Disconnect main rotor field leads at F1+ and F2- and disconnect leads from diodes CR1-CR6.
3. Test between exciter lead pairs T1-T2, T2-T3, and T1-T3; resistance should be 0.6 to 0.7 ohms at 68 deg F (20 deg C).
4. Connect ohmmeter between each CR lead and rotor laminations; less than one megohm indicates defective ground insulation.

Tools: ohmmeter

1. Disconnect F1+ and F2- exciter field leads from terminal block in generator end bell.
2. Measure resistance between field leads; should be 13.05 to 15.95 ohms at 77 deg F (25 deg C).
3. Connect ohmmeter between either field lead and exciter stator laminations on highest range; resistance must be one megohm or greater.

Tools: accurate ohmmeter

1. Disconnect all leads from assembly to be tested.
2. Connect one test lead to F1+ stud and other lead to CR1, CR2, and CR3 in turn; record resistance of each.
3. Connect one lead to F2- stud and other lead to CR4, CR5, and CR6 in turn; record resistance of each.
4. Reverse ohmmeter leads and record resistance values again.
5. All readings should be high in one test and low in the other; if high or low in both, replace the assembly.