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Cummins/Onan Cummins DFFB Engine

Name: Cummins/Onan Cummins DFFB Engine
Brand: Cummins/Onan

The Cummins/Onan Cummins DFFB is an engine. It powers generator sets from Cummins/Onan, including the DFFB.

Also known as: Cummins Cummins DFFB

Part of the Cummins/Onan Cummins engine family — 4 variants share parts & fitment.

On this pageSpecs Generator sets FAQ Torque & specs Fluids Fault codes Procedures Wiring

Engine specifications

Generator sets powered by this engine

Cummins/Onan DFFB

How to read your Cummins/Onan engine serial & model number →

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Float switch assembly float lift clearance below C-clip stop	1/8	inch (3 mm)	use a feeler gauge
Clearance	Generator-to-engine angular alignment (T.I.R.)	.001 in. per inch of radius (center of shaft to indicator axis), maximum	in	750 kW gensets and larger
Other	AVR Droop setting	5	% at full load, 0 PF
Other	AVR voltage regulation (load regulation)	approximately ±0.5	% RMS
Other	Battery specific gravity (high ambient, above 95F/35C)	1.225		recommended to reduce electrolyte loss
Other	Battery specific gravity (recharge threshold)	below 1.260
Other	GOV GAIN default value for paralleling applications	70	%
Other	Over/Under Frequency Sensor Module - Over Hz Set, 50 Hz nominal	55	Hz	reset 53 Hz
Other	Over/Under Frequency Sensor Module - Over Hz Set, 60 Hz nominal	65	Hz	reset 63 Hz
Other	Over/Under Frequency Sensor Module - Under Hz Set, 50 Hz nominal	45	Hz	reset 47 Hz
Other	Over/Under Frequency Sensor Module - Under Hz Set, 60 Hz nominal	55	Hz	reset 57 Hz
Other	Over/Under Voltage Sensor Module time delay	typically 25 percent, approximately 2.5	seconds
Other	Overcrank cranking limit	75	seconds	three 15-second cranking cycles with two 15-second rest periods
Other	REG VHZ (underfrequency roll-off) adjustable range	1 through 50; normal range 7 through 21
Other	Start delay adjustment range	0 to 300	seconds
Other	Stop delay adjustment range	0 to 600	seconds
Other	Under Frequency Roll Off (UFRO) knee point, 50 Hz units	48 to 49	Hz
Other	Under Frequency Roll Off (UFRO) knee point, 60 Hz units	58 to 59	Hz
Pressure	Engine oil pressure - K19 normal	50-70	psi (345-482 kPa)	run mode
Pressure	Engine oil pressure - K38 normal	45-65	psi (310-448 kPa)	run mode
Pressure	Engine oil pressure - K50 normal	50-70	psi (345-482 kPa)	run mode
Pressure	Engine oil pressure - L10/M11 normal	30-50	psi (207-345 kPa)	run mode
Pressure	Engine oil pressure - NTA 855 normal	35-50	psi (241-345 kPa)	run mode
Pressure	Engine oil pressure - V28 normal	50-90	psi (345-620 kPa)	run mode
Pressure	Engine oil pressure shutdown limit - L10/M11	20	psi (138 kPa)	run mode value
Pressure	Engine oil pressure shutdown limit - L10/M11	8	psi (55 kPa)	idle mode value
Pressure	Engine oil pressure warning limit - L10/M11	12	psi (83 kPa)	idle mode value
Pressure	Engine oil pressure warning limit - L10/M11	25	psi (172 kPa)	run mode value
Pressure	K19 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K19 engine normal oil pressure	50-70	psi (345-482 kPa)	normal run
Pressure	K19 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	K38 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K38 engine normal oil pressure	45-65	psi (310-448 kPa)	normal run
Pressure	K38 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	K50 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	K50 engine normal oil pressure	50-70	psi (345-482 kPa)	normal run
Pressure	K50 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Pressure	L10/M11 engine idle oil pressure	15	psi (103 kPa)	idle
Pressure	L10/M11 engine normal oil pressure	30-50	psi (207-345 kPa)	normal run
Pressure	L10/M11 oil pressure shutdown limit	20	psi (138 kPa)	run mode value
Pressure	L10/M11 oil pressure shutdown limit	8	psi (55 kPa)	idle mode value
Pressure	L10/M11 oil pressure warning limit	12	psi (83 kPa)	idle mode value
Pressure	L10/M11 oil pressure warning limit	25	psi (172 kPa)	run mode value
Pressure	Low oil pressure shutdown	below 14	psi (97 kPa)	time delayed ~10 seconds following starter disconnect
Pressure	NTA 855 engine normal oil pressure	35-50	psi (241-345 kPa)	normal run
Pressure	NTA 855 oil pressure shutdown limit	25	psi (172 kPa)	run mode value
Pressure	NTA 855 oil pressure shutdown limit	8	psi (55 kPa)	idle mode value
Pressure	NTA 855 oil pressure warning limit	12	psi (83 kPa)	idle mode value
Pressure	NTA 855 oil pressure warning limit	30	psi (207 kPa)	run mode value
Pressure	Pre-low oil pressure warning	20 or less	psi (138 kPa)
Pressure	V28 engine idle oil pressure	20	psi (138 kPa)	idle
Pressure	V28 engine normal oil pressure	50-90	psi (345-620 kPa)	normal run
Pressure	V28 oil pressure shutdown/warning limits	shutdown 35 psi (241 kPa) run; warning 40 psi (276 kPa) run; shutdown 10 psi (69 kPa) idle; warning 15 psi (103 kPa) idle	psi (kPa)
Resistance	Circuit breaker insulation resistance (ground indication)	less than 100,000	ohms	tested with 500V insulation resistance meter
Resistance	Coolant temperature sender resistance	500 to 2k	ohms
Resistance	Current transformer (PT) primary	1K-2.5K	ohms
Resistance	Current transformer (PT) secondary	140-225	ohms
Resistance	Exciter rotor winding resistance (per pair)	approximately 0.136	ohms
Resistance	Exciter stator winding - frame size 4C/4D/4E/4F	0.136	ohms	at 68°F (20°C) + 10%
Resistance	PMG stator resistance (HC4)	4.6	ohms

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Ambient	Capacity	Notes
Coolant	soft water / E.G. / DCA mixture			Cooling system to be filled with soft water/E.G./DCA mixture (on-site review checklist).
Fuel	Diesel			Day tank fuel transfer pump maintains reservoir of diesel fuel in the day tank.
Grease	Lithium based grease, Mobilux No. 2 or Shell Alvania R3	-30°C to 120°C	2.74 oz (81 ml)	End bearing lubricant; grease equally divided between bearing, bearing cap cavity and bearing cartridge cavity.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Fault codes

Code	Name	Meaning	Severity	Action
101	IDLE MODE	Indicates that the engine is operating in idle mode. Grounding the engine idle input causes generator build-up to be inhibited and the engine to be governed at 800 RPM.	Warning	Remove ground from engine idle input to return to normal speed and voltage.
102	EMERGENCY STOP	Indicates local or remote Emergency Stop.	Shutdown	Turn the switch clockwise and allow it to pop out (local only). Move the Run/Off/Auto switch to Off. Press the Reset switch. Select Run or Auto, as required.
200	LOW OIL PRESSURE	Indicates engine oil pressure has dropped to an unacceptable level.	Warning	If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow 201-SHUTDOWN procedure. Access the Oil Pressure menu prior to clearing the fault.
201	LOW OIL PRESSURE	Indicates engine oil pressure has dropped below the shutdown trip point.	Shutdown	Check oil level, lines and filters; replenish if low; reset control and restart.
204	OIL PRES SENDER	Indicates that the control has sensed that the engine oil pressure sender is out of its working range.	Warning	Check that the engine oil pressure sender is properly connected.
210	LOW COOLANT TEMP	Warning occurs when engine coolant temperature is 70°F (21°C) or lower.	Warning	Indicates engine coolant heater is not operating or is not circulating coolant. Check coolant heater power supply, low coolant level, and heater element current draw.
211	HIGH COOLANT TEMP	Indicates the engine coolant temperature is getting close to the recommended maximum temperature limit: 215° F (102° C) − standby or 207° F (97° C) − primary.	Warning	Reduce load if possible; check air inlets and outlets and remove obstructions to airflow.
212	HIGH COOLANT TEMP	Indicates engine has overheated (coolant temperature above 215° F (102° C) − standby or 207° F (97° C) − primary).	Shutdown	Allow engine to cool; check airflow, fan belt, coolant mixture, blower fan and circulation pumps.
213	COOLANT SENDER	Resistance of the coolant temperature sender is out of range.	Warning	Check the resistance of the sender; should be 500 to 2k ohms.
214	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Warning	Check coolant level in radiator and coolant recovery bottle; replenish if low; look for leaks.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Shutdown	Allow engine to cool; check coolant level and leakage points; reset control and restart.
220	MAG PICKUP	Mag pickup speed indication is not being sensed or does not match generator set output frequency.	Shutdown	Restart and check RPM; check PCC model setting; inspect and test MPU.
221	FAIL TO CRANK	Possible fault with control or starting system.	Shutdown	Check fuse F3 on the Engine Interface board. Check for poor battery cable connections; clean battery cable terminals and tighten. Recharge or replace a discharged or defective battery.
222	OVERCRANK	Possible fuel system problem.	Shutdown	Check for empty fuel tank, leaks, plugged fuel lines; replace dirty fuel or air filter; reset and restart.
223	OVERSPEED	Indicates engine has exceeded normal operating speed. (115% ±1% of nominal).	Shutdown	Check mechanical fuel linkage and actuator; check governor output module (A38) and digital board (A32).
224	FAIL TO SYNCHRONIZE	Generator set has not synchronized to the system bus within the allowable time frame.	Warning	Check governor system stability; adjust governing and synchronizer parameters; check fuel system.
226	FAIL TO CLOSE	Paralleling breaker has been given a signal to close, but has not closed properly.	Shutdown	Verify breaker charging mechanism; check close signal; verify auxiliary contact signals.
230	LOW DC VOLTAGE	Indicates battery voltage is below 10 VDC.	Warning	Recharge or replace the battery; check the battery charger fuse. Clean and tighten battery cable connections. Check engine DC alternator; replace if normal charging voltage is not obtained. Check float level if applicable.
231	HIGH DC VOLTAGE	Indicates battery voltage exceeds 32 VDC.	Warning	Lower battery charger float level if applicable; check engine DC alternator.
232	WEAK BATTERY	Indicates battery voltage drops below 60% of nominal for two seconds, during starting.	Warning	See LOW DC VOLTAGE 230.
240	LOW FUEL−DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.
241	LOW FUEL	Low fuel signal received.	Warning	Check fuel supply and replenish; check for short to ground in external wiring.
250	EEPROM ERROR	PCC memory error; data corruption of critical operating parameters.	Shutdown	Perform initial start setup procedure; replace digital board (A32) if fault repeats.
251	EEPROM ERROR	PCC memory error; data corruption of noncritical operating parameters.	Warning	Perform adjustment and calibration procedures; replace digital board (A32) if fault repeats.
252	EEPROM ERROR	PCC memory error; data corruption of noncritical operating parameters.	Warning	Verify selected values; repeat save operation; replace digital board (A32) if fault repeats.
260	CUSTOMER FAULT 1	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Isolate source of false signal; repair external wiring or replace A34.
261	GROUND FAULT	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Isolate source of false signal; repair external wiring or replace A34.
262	RUPTURE BASIN	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Isolate source of false signal; repair external wiring or replace A34.
263	HIGH GEN TEMP	When a customer defined input is closed to ground, the corresponding fault message is displayed. Default message; editable for customer site requirements.	Warning	Isolate source of false signal; repair external wiring or replace A34.
270	PHASE ROTATION	The phase relationship between the generator set and the system bus is not matched.	Shutdown	Verify genset phase rotation matches bus; verify control wiring to bus PT module.
272	FIRST START	PowerCommand control is not receiving a proper signal from the system master first start sensor.	Warning	Verify Master First Start Sensor and interconnection wiring.
301	HIGH AC VOLTAGE	One or more phase voltages exceeded 130% of nominal, or exceeded 110% of nominal for 10 seconds.	Shutdown	Check PCC, alternator, excitation circuit, and PT/CT module wiring.
303	LOW AC VOLTAGE	One or more phase voltages dropped below 85% of nominal for 10 seconds.	Shutdown	Check PMG/field wiring, rotating rectifier, load and connectors.
313	UNDER FREQUENCY	Indicates that engine speed has dropped below 90% of nominal for 10 seconds. Five seconds before shutdown, a Load Dump signal is initiated.	Shutdown	Check fuel supply, intake air supply and load.
320	OVERCURRENT	Indicates that generator output current has exceeded 110% of rated for 60 seconds.	Warning	Check load and load lead connections.
321	OVERCURRENT	Indicates that generator output current has exceeded 110% of rated, and that a PCC time/current calculation has initiated an overcurrent shutdown.	Shutdown	Check load and load lead connections.
322	SHORT CIRCUIT	Indicates that generator output current has exceeded 175% of rated.	Shutdown	Check load and load lead connections.
330	OVERLOAD	Three-phase power output exceeds 105% of standby (or 115% of prime) rating.	Warning	Check load and load lead connections.
335	REVERSE POWER	Power is flowing into the generator set rather than out from the unit.	Shutdown	Verify CT connections, load sharing lines, and generator set frequency/voltage.
337	LOSS OF EXCITATION	Alternator excitation system is improperly adjusted or has failed.	Shutdown	Check output voltage calibration, load sharing lines, and leading power factor loads.
FAULT 1	Fault 1	Undedicated customer-defined fault; may be programmed as timed or non-timed shutdown or fault light only.
FAULT 2	Fault 2	Undedicated customer-defined fault, same features as Fault 1.
HI ENG TEMP	High Engine Temperature	Engine shut down due to critically high coolant temperature (above 215F/102C).	Shutdown
LO FUEL	Low Fuel	Fuel supply is marginally low, if equipped (Detector-12).	Warning
LO OIL PRES	Low Oil Pressure	Engine shut down due to critically low oil pressure (below 14 psi/97 kPa).	Shutdown
LOW ENG TEMP	Low Engine Temperature	Engine water jacket temperature is 70F/21C or lower; indicates possible inoperative coolant heater (Detector-12).	Warning
OVERCRANK	Overcrank	Starter locked out because of excessive cranking time (limited to 75 seconds).	Shutdown
OVERSPEED	Overspeed	Engine shut down because of excessive speed.	Shutdown
PRE HI ENG TEMP	Pre-High Engine Temperature	Coolant temperature is marginally high (205F/97C or higher).	Warning	Attend to when generator set is shut down.
PRE LO OIL PRES	Pre-Low Oil Pressure	Engine oil pressure is marginally low (20 psi/138 kPa or less).	Warning	Attend to when generator set is shut down.
RUN	Run	Green lamp comes on when both primary and secondary starter circuits open after unit starts.	Info
SWITCH OFF	Switch Off	Generator set is not in automatic start operation mode (flashing red).	Info

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Aligning Generator with Engine (Angular Alignment) adjustment

⚠ Accidental starting of the generator set during this procedure presents the hazard of severe personal injury or death.

Tools: Dial indicator, Shims

Disconnect the negative (-) battery cable(s) before beginning.
Fasten a dial indicator to the generator shaft or cooling fan with the sensing point on the capscrew head or flat surface of the drive disc at the bolt circle diameter.
Bar the engine over in a clockwise rotation as viewed from engine flywheel; do not allow it to roll back on compression.
Determine the total indicator reading (T.I.R.) as the sum of the maximum positive and negative dial indicator readings over one revolution.
Measure the distance from the center of the generator shaft to the indicator measuring point.
Measure the distance from the generator side of the flex discs to the center of the generator mounting bolt.
Compare the distances; multiply this ratio times one half the T.I.R. to approximate the amount of shims to remove or add.

Angular Alignment Procedure (Generator to Engine) adjustment

⚠ Accidental starting during this procedure presents the hazard of severe personal injury or death.

⚠ Do not bar engine over by prying on fan blade.

Tools: dial indicator

Disconnect the negative (-) battery cable(s) before beginning.
Fasten a dial indicator to the generator shaft or cooling fan with sensing point resting on the drive disc capscrew head/flat surface at the bolt circle diameter.
Bar the engine over in a clockwise rotation as viewed from the engine flywheel; do not allow it to roll back on compression at the end of travel of each reading.
Record the total indicator reading (T.I.R.) as the sum of the maximum positive and negative dial indicator readings over one engine revolution.
Compare the measured T.I.R. to the maximum allowed (.001 in. per inch of radius from center of shaft to indicator axis); add or remove shims under the generator mounting feet to correct.

Axial Alignment Procedure (Generator to Engine) adjustment

Tools: dial indicator

Fasten a dial indicator holding device to the skid base, engine block, or generator shell with the sensor point resting on the generator shaft hub.
Bar the engine over in a clockwise rotation through a couple of rotations, recording indicator readings at eight equally spaced points around the shaft diameter to obtain axial T.I.R.
Reduce the measured T.I.R. runout by one half if excessive vibration remains after angular alignment.

Generator/PCC Control Isolation Procedure diagnostic

⚠ HIGH VOLTAGE. Touching uninsulated high voltage parts inside the control box can result in severe personal injury or death.

Tools: Voltmeter, Jumpers, 12 volt battery

Throw the line circuit breaker OFF and shut down the set.
Remove accessory box cover; remove plug P10 from A37 J10.
Prepare to measure output voltage across generator terminals.
Connect 12V battery jumpers to X (P10-6 red) and XX (P10-3 brown).
Check polarity; incorrect polarity makes the test inconclusive.
Start set and connect battery negative to the XX lead.
Rated or higher balanced voltage means generator circuitry is OK.
Unbalanced voltage: troubleshoot main stator; low voltage: exciter/field.

Insulation Resistance (Megger) & Polarization Index (PI) Testing diagnostic

⚠ The windings of medium-voltage (601 through 15,000 volts) generator sets must be dry before the generator is operated.

Tools: Megger or insulation resistance meter, Grounding cluster, High voltage gloves

Perform the Generator Set Grounding Procedure.
Disconnect plug J10 from A37 and AC control leads 4,5,6,7,8.
If RTD option installed, ground all six RTD temperature leads (18 leads).
Perform Insulation Resistance Test and PI Test for desired windings.
Megger test: apply voltage for up to one minute.
PI test: apply voltage for ten minutes; record 1-minute and 10-minute readings.
PI ratio of 2 or greater is good for new and in-service sets.
Investigate and correct low readings before returning set to service.

Megger and PI Test diagnostic

⚠ Medium-voltage (601 to 15,000 volts) windings must be dry before the generator is operated.

Tools: Megger or Insulation Resistance Meter, Wheatstone bridge or digital ohmmeter, Grounding Cluster

Perform the Generator Set Grounding Procedure.
Disconnect plug J10 from the voltage regulator output module and the AC control leads (marked 4, 5, 6, 7, 8).
If RTD option installed, ground all six RTD temperature leads (18 leads total).
Perform the Winding Resistance Test for the desired windings.
Perform the Insulation Resistance (Megger) Test and PI Test for the desired windings.
Megger test: apply voltage for up to one minute.
PI test: apply voltage for ten minutes; record resistance at one minute and ten minutes.
PI is the ten-minute reading divided by the one-minute reading; ratio of two or greater is good.

Testing Diodes diagnostic

⚠ Layers of dust can cause diodes to overheat and fail. Brush dust off regularly.

Tools: Ohmmeter

Disconnect the diode pigtails from the terminal posts.
Using an ohmmeter, measure resistance between pigtail and mounting plate.
Reverse meter test probes and repeat the tests.
Resistance should be high in one direction and low in the other.
If high or low in both directions, replace the diode.

Testing the Float Switch Assembly diagnostic

Tools: Ohmmeter, Feeler gauge

Remove the fuel pump control cover, disconnect the wiring jack and unscrew the assembly from the top of the day tank.
With an ohmmeter, test for electrical continuity between each pair of colored leads while holding the assembly vertical; all readings should be zero.
Lift each float, in turn, to 1/8 inch (3 mm) below the C-clip stop above it and test for continuity; all readings should be infinity.
Use pipe thread sealant when replacing the assembly.

Testing the PMG diagnostic

⚠ HAZARDOUS VOLTAGE. Touching uninsulated parts inside the control housing and power output boxes can result in severe personal injury or death.

Tools: Digital multimeter, Wheatstone bridge or digital ohmmeter

Disconnect PMG leads PMG 2, PMG 3, PMG 4 from connectors in AC harness.
Start the engine and let speed stabilize.
Measure voltage across lead pairs PMG 2&3, 3&4, 4&2.
Voltage should be at least 150 VAC for 50 Hz sets, 180 VAC for 60 Hz.
Stop set; measure resistance across the lead pairs with a Wheatstone bridge.

Current Transformer (CT) Installation installation

⚠ Improper installation of CTs will cause a “335 Reverse Power” shutdown error.

Orient CT dot toward the generator (conventional current into dot).
Route U/A, V/B, W/C load leads through CT21, CT22, CT23.
6 lead sets: route generator output leads through the CTs.
12 lead sets: route load wires through the CTs.
Connect CT secondary wire 1 to CT pin 1; 2/3 to pin 2 (high voltage) or pin 3 (low voltage).

Fuel Transfer Pump Motor Connections installation

Remove the end bell cover for access to the motor wiring terminals.
Disconnect the brown lead from motor terminal P103-3 and connect it to terminal P103-6.
Disconnect the red lead from motor terminal P103-2; reconnect to the piggy-back terminal on the lead at motor terminal P103-3.
Cut the white lead from its ring connector at motor terminal P103-4 and strip 1/2 inch (12 mm) of insulation for splicing to harness lead P103-WHITE.
Connect each lead of the five-lead wiring harness to the motor terminal or lead marked on it.
Connect the red motor lead to the piggy-back terminal at motor terminal P103-3.
Secure the end bell cover.

Magnetic Speed Pickup Unit (MPU) Installation installation

⚠ Do not use fan blade to bar over engine. That can damage blades and cause property damage and personal injury.

Bar the engine until a flywheel gear tooth lines up in center of mounting hole.
Thread the sensor in gently by hand until it just touches the gear tooth.
Back it out one quarter turn.
Set the locknut.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

Phase	Connection	Leads	Notes
	12 lead generator sets	Load wires are routed through the CTs	Reconnectable gensets (12 leads) have dual secondary CTs (3 pins); CT wire 2/3 to pin 2 (high voltage) or pin 3 (low voltage).
	6 lead generator sets	Generator output leads are routed through the CTs	Non-reconnectable gensets (6 leads) have single secondary CTs (2 pins).
	Cummins PowerCommand generic AC Reconnect Wiring Diagram 625-2755 (Rev. D) and 625-3100 (Rev. F)		Applies to models DFAA, DFAB, DFAC, DFBF, DFCB, DFCC, DFEB, DFEC, DFFB, DFGA, DFGB, DFJA, DFJB, DFJC, DFJD, DFLB, DFLC, DFLD, DFMB (625-2755) and models DFAA-DFMB plus DFCE, DFED, DQAA, DQAB, DQBA, DQBB (625-3100).
A (U)	CT21	U load leads (A phase)	CT dot must face the generator; CT terminal 1 connects to metering circuit, terminal 2/3 to ground.
B (V)	CT22	V load leads (B phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
C (W)	CT23	W load leads (C phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Parts cataloged across the Cummins/Onan Cummins family

103

Part #	Description	Category
140-2097	Cleaner, Air (Includes Elements)	air_filter
140-2463	140-2464 3 98-5822 4 309-0436 505-0117 5 309-0437 SOS- SOS 503 8 501 9 1 SO- lO 130 11 98	air_filter
140-2464	Air Cleaner - Safety Standard	air_filter
502-0942	Elbow - 90 °	hose
503-0189	Clamp, Hose	hose
870-0257	Nut, Locking (5/16−18) * − Parts Used On Heat Exchanger Installations With Automatic Water Regulator # − Cut Off And Discard Swivel Connector End Of Hose So That 1/8 NPT Connector End Measures Length As Indicated Above + − Parts Used On Heat Exchanger Installations Without Automatic Water Regulator	hose
130-3729		other_service
130-3730		other_service
130-3731		other_service
130-3732		other_service
130-3734		other_service
130-3736		other_service
130-3737		other_service
130-3738		other_service
130-3739		other_service
130-3740		other_service
130-3744		other_service
140-1260	Fitting, Safety Filter	other_service
140-1548	Indicator, Service	other_service
140-2052	Band	other_service
140-2098	Hood, Air Inlet (Includes Mounting Clamp)	other_service
140-2099	Band	other_service
140-2459	13racket	other_service
140-2472	Tube	other_service
140-2474	Tube	other_service
155-0658		other_service
155-2437		other_service
159-1208		other_service
159-1231		other_service
159-1232		other_service
193-0029		other_service
193-0128	Gauge, Fuel Pressure (0-200 Lbs)	other_service
300-4111-02	Board, Relay - Alarm (Includes Relay)	other_service
300-4111-04		other_service
303-1704	EIbow	other_service
308-0916	821-OCJIO	other_service
309-0180		other_service
309-0437	(222"F)	other_service
319-0489		other_service
319-0490		other_service
323-1304	tiotming, Umector	other_service
333-2947	OFAA. OFAB, WAC	other_service
333-2948	OFOF. OFCB. OFCC	other_service
338-2446	Harness	other_service
338-2538	Harness	other_service
415-0565-02		other_service
416-0444	Cable, Battery - Negative	other_service
416-0446	Cable, Battery - Jumper	other_service
416-0960		other_service
501-0084	Line, Fuel - Flexible "FUEL OUT" (45' 7/8-14 Female Swivel x	other_service
501-0216	Line, Fuel	other_service
501-0552		other_service
502-0034	Tube	other_service
502-0080	F1ange	other_service
503-0881	Element	other_service
503-0882	Elbow	other_service
503-1487		other_service
503-1731		other_service
505-0004	Nipple, Pipe (1.0 x 1.50)	other_service
505-0050	Elbow, Street (1/2' x 90 ° )	other_service
505-0084		other_service
505-0098	Band	other_service
505-0151	S26-0238	other_service
505-0166	Tee, Pipe (3/4º)	other_service
505-0356	Elbow	other_service
505-1384	Bushing	other_service
508-0015	Washer, Insulating - Fiber (#8)	other_service
670-0517-902	standoff(wlbw)(q	other_service
800-0052	Screw	other_service
800-0065		other_service
800-0071	Part 800-0071	other_service
800-0088	Elbow	other_service
800-0215		other_service
800-0236		other_service
800-0270	DCA4 Service Pre-Charging Complete System	other_service
821-0010	Screw, Self -1ocking - Hex Washer Head (1/4-20 x 1/2')	other_service
821-0016	Screw, Self-locking - Hex (5/16-18 X 3/4')	other_service
821-0029	Screw, Self–Locking – Hex Washer Head (3/8–16 x 3/4")	other_service
821-0033	Screw, Self–Locking – Hex Washer Head (7/16–14 x 3/4")	other_service
850-0055	Washer, Lock - Spring (7/16")	other_service
850-0060	Screw, Cap - Hex Head (5/16-18 X 7-1/2" )	other_service
850-2008	Washer, Lock (M8)	other_service
856-0008	Washer, Lock - EIT (5/16'1)	other_service
856-0010	Washer, Lock - EIT (3/8')	other_service
856-0013	Washer, Lock - W/EIT (1/2)	other_service
862-0035		other_service
870-0212	Nut, Locking (1/4-20)	other_service
870-0221	Harness, Wiring - Remote Control - Spec S (Includes Parts Marked +) Cable - 10 Feet Cable - 30.Feet Housing, Connector Pin Pin, Connector - Male Control	other_service
870-0281	Nut, Self-Locking – Hex Washer Head (3/8–16)	other_service
870-0437		other_service
921-0018		other_service
960-0138		other_service
960-0139		other_service
960-0240		other_service
399-0117	Pump, Fuel Transfer	pump
509-0272	Seal	seal
509-0272-02	Seal	seal
193-0244	Sender, Pressure - 0i1	sensor
193-0322	Sender, Level - Coolant	sensor
193-0353	Sender, Temperature - Oil	sensor
309-0269	Switch, Low Engine Temperature (S4)	sensor
416-0632	Cable, Electrical - Starter To Ground	starter
333-0468	Thermostat	thermostat

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Common questions

Which generators use the Cummins/Onan Cummins DFFB engine?

The Cummins/Onan Cummins DFFB powers 1 generator set(s), including Cummins/Onan DFFB.