Home›Engines›Cummins/Onan KTTA50

Cummins/Onan KTTA50 Engine

The Cummins/Onan KTTA50 is an engine. It powers generator sets from Cummins/Onan, including the DFLC and DFLE. It holds 169 L (44.6 gal) of oil and 386 L (102.0 gal) of coolant.

Also known as: Cummins KTTA50

Part of the Cummins/Onan KTTA50 engine family — 3 variants share parts & fitment.

169.0 L

Oil capacity

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

Engine specifications

Oil capacity	169.0 L
Coolant capacity	386.0 L

Generator sets powered by this engine

Cummins/Onan DFLC Cummins/Onan DFLE

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

Common problems

Engine cranks but fails to start
Cause: Empty fuel tank, fuel leaks, or plugged fuel lines
Fix: Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required.
EEPROM ERROR — Warning 251
Cause: Indicates PCC memory error. Data corruption of noncritical operating parameters.
Fix: Contact an authorized service center.
WEAK BATTERY — Warning 232
Cause: Indicates battery voltage drops below 60% of nominal for two seconds, during starting. Discharged or defective battery.
Fix: See Warning message 230, LOW DC VOLTAGE.
UNDER FREQUENCY — Shutdown 313
Cause: Indicates that engine speed has dropped below 90% of nominal for 10 seconds. NOTE: Five seconds before shutdown, a Load Dump signal is initiated.
Fix: Contact an authorized service center.
SHORT CIRCUIT — Shutdown 322
Cause: Indicates that generator output current has exceeded 175% of rated.
Fix: Contact an authorized service center.
REVERSE POWER — Shutdown 335
Cause: Indicates improper CT or PT phasing. (Non-parallel units only.)
Fix: Contact an authorized service center.
LOW OIL PRESSURE — Shutdown 201
Cause: Indicates engine oil pressure has dropped below the shutdown trip point.
Fix: Check oil level. If oil level is low, replenish. Reset control and restart. Oil pressure limits are listed in Specifications. Contact an authorized service center.
LOW AC VOLTAGE — Shutdown 303
Cause: Indicates that one or more of the phase voltages has dropped below 85% of nominal for 10 seconds.
Fix: Contact an authorized service center.
HIGH COOLANT TEMP — Shutdown 212
Cause: Indicates engine has overheated (coolant temperature has risen above the shutdown trip point).
Fix: Allow engine to cool down completely before proceeding with the following checks: Check coolant level and replenish if low. Look for coolant leakage and repair if necessary; Check for obstructions to cooling airflow and correct as necessary; Check fan belt and repair or tighten if necessary; Reset control and restart after locating and correcting problem. Contact an authorized service center if none of the above.
HIGH AC VOLTAGE — Shutdown 301
Cause: Indicates that one or more of the phase voltages has exceeded 130% of nominal, or has exceeded 110% of nominal for 10 seconds.
Fix: Contact an authorized service center.
Warning, Shutdown, and Non-Automatic lamps are not lit. Digital display shows main menu or selected menu.
Cause: Indicates all engine systems are normal.
Fix: No corrective action required.
The FAULT 1 or FAULT 2 fault lamp lights. Engine shuts down immediately, engine runs for several seconds and then shuts down, or engine continues to run.
Cause: The standard undesignated fault functions are programmed to shut down the set when a fault is sensed. Fault 1 is time delayed while Fault 2 is immediate. The nature of the fault is an optional selection that is determined when the set installation is designed. The undesignated fault functions may also be programmed for non-shutdown or non-time delay.
The BASIN (optional) fault lamp lights. Engine continues to run or is in standby mode. (Engine can be programmed to shut down.)
Cause: Indicates fuel is leaking from inner tank to outer basin or the sensor may be defective.
Fix: Contact an authorized service center for service.
SWITCH OFF lamp flashes.
Cause: Indicates Run/Stop/Remote switch is in the Stop position which will prevent automatic starting if an automatic transfer switch is used.
Fix: Move the Run/Stop/Remote switch to the Remote position for automatic starting.
RUPTURE BASIN — Warning 262
Cause: When any one of these customer defined inputs is closed to ground, the corresponding fault message is displayed. The nature of the fault is an optional customer selection. These fault functions can be programmed to initiate a shutdown or a warning. As indicated by the Warning lamp, a warning response has been preselected.
Fix: Note: Customer fault messages are editable. The message displayed for the code shown (260 thru 263) may have been edited and may not appear as shown in this table.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan KTTA50.

Service intervals

Item	Action	Hours	Months	Notes
crankcase oil	Change	50 hr		First service — Drain and replace the crankcase oil after the first 50 hours of operation on new generator sets (break-in)
Check Electrolyte Level (batteries)	Check	200 hr		At least every 200 hours of operation
Change Crankcase Oil and Filter	Change	250 hr	12 mo	If used for standby applications, change oil every 12 months or 250 hours, whichever comes first (footnote X6)
Crankcase oil and filter	Change	250 hr	12 mo	Standby applications: change oil every 12 months or 250 hours, whichever comes first
Grease generator bearing (P7)	Lubricate	4000 hr		Table 5-2 explicit interval; grease type Kluber ASONIC GHY72, 75 grams
Generator bearing (P7 only)	Lubricate	4500 hr		Re-lubrication period 4000-4500 hours; 75 grams Kluber ASONIC GHY72
Exercise generator set	Test		1 mo	At least once a month for a minimum of 30 minutes, under not less than 30 percent of nameplate rating
Rupture basin leak detect switch	Test		12 mo	Some areas may require weekly inspections by safety code.

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

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Air cleaner nozzle distance from element	at least 1 (25)	inch (mm)
Clearance	Angular alignment T.I.R. limit	not more than .001	in per inch of radius	center of shaft to indicator axis
Clearance	Angular alignment maximum T.I.R.	0.001	inch per inch of radius (center of shaft to indicator axis)	measuring deflection to bolt heads
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
Clearance	MPU sensor to gear tooth adjustment	back out one quarter turn	turn	after contacting gear tooth
Gap	Float switch lift to test open	1/8	inch	below C-clip stop
Gap	MPU sensor to flywheel ring gear tooth	back it out one quarter turn	turn	sensor threaded in until it just touches gear tooth
Other	AVR Droop setting	5	% at full load, 0 PF
Other	AVR voltage regulation (load regulation)	approximately ±0.5	% RMS
Other	Air cleaner element cleaning air pressure	30 (207)	psi (kPa)	low pressure compressed air through element from clean side
Other	Angular alignment maximum T.I.R.	.001 inches per inch of radius	in/in	center of shaft to indicator axis
Other	B+ output fuse	10	amp	F1, Base board, 12/24 volt
Other	Battery charging current	45	Amps
Other	Battery electrolyte specific gravity	1.260		at 80°F
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	Battery specific gravity - charge threshold (below this, charge battery)	1.215
Other	Battery specific gravity - fully charged (corrected)	1.260
Other	Battery specific gravity, fully charged	approximately 1.260	specific gravity	at 80 F (27 C)
Other	Continuous crank without cycle cranking option (PCC)	up to 75	seconds
Other	Customer Output relay contact rating	2	amps at 30 VDC	TB1 customer outputs 1-4, normally open
Other	Fuel lift height limit	6	feet	(1.8 meters) between fuel lift pump and bottom of dip tube
Other	GOV GAIN default value for paralleling applications	70	%
Other	Ground Fault Relay current setting	5 to 1200	amperes	optional GFR
Other	Ground Fault Relay time delay setting	0 to 1	second	optional GFR
Other	Low oil pressure / high engine temperature fault time delay after starter disconnect	about 10	seconds
Other	Maximum cranking voltage drop	2	volts	difference between battery and starter terminals while cranking
Other	Optional control relay (K11/K12/K13) contact rating	10	amps at 600 VAC
Other	Output frequency adjustment range	+/- 5	%	set running, not in idle mode
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	Overcrank cranking limit (standard control)	75	seconds
Other	Overcrank cycle cranking (Detector, standard)	three 15-second cranking cycles with two 15-second rest periods	seconds
Other	Overcrank cycle cranking (PCC)	3, 4, or 5 cycles; crank and rest times 7 to 20	seconds
Other	Overcrank cycling option	three 15-second cranking cycles with two 15-second rest periods		12-lamp control
Other	Overcrank limit (Detector, optional)	75	seconds
Other	Overcurrent shutdown threshold	110% of rated	% of rated	PCC time/current calculation
Other	Overcurrent warning threshold	110% of rated for 60 seconds	% of rated	generator output current
Other	Overload warning threshold	105% of standby or 115% of prime	% of rating	three-phase power output; load dump after five seconds, warning after 60 seconds
Other	REG VHZ (underfrequency roll-off) adjustable range	1 through 50; normal range 7 through 21
Other	Short circuit shutdown threshold	175% of rated	% of rated	generator output current
Other	Start delay (PCC, remote start in Auto)	0 to 300	seconds
Other	Start delay adjustment range	0 to 300	seconds
Other	Stop delay (PCC, remote stop in Auto)	0 to 600	seconds
Other	Stop delay adjustment range	0 to 600	seconds
Other	Switched B+ output fuse	5	amp	F2, Base board, 12/24 volt
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
Other	Under-frequency roll-off threshold (UFRO)	typically 59 Hz for 60 Hz applications and 49 Hz for 50 Hz applications	Hz	AVR UFRO pot preset
Other	Weak battery warning threshold	below 60% of nominal for two seconds	% of nominal	during starting
Pressure	Air cleaner element cleaning, compressed air pressure	30	psi (207 kPa)	blow through element from clean side; nozzle at least 1 inch (25 mm) away
Pressure	Detector oil pressure normal range after reset	25 to 40	psi (172 to 275 kPa)
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

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	Standard	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).
Coolant	water/antifreeze mixture (permanent type antifreeze)	Clean, low mineral content water free of chloride, sulphate or acid			Mix water and antifreeze per supplier recommendation for lowest expected ambient temperature; do not use antifreeze containing anti-leak additives
Engine oil	SAE 5W synthetic	API class CC/CD; sulphated ash content not exceeding 1.85 percent; pour point 9°F (5°C) below lowest expected temperature; viscosity 10,000 mPa.s maximum at -31°F (-35°C) and 4.1 mm2/s minimum at 212°F (100°C)	above -25°C		Recommended when ambient temperature is consistently below -13°F (-25°C) and there is no provision to keep the engine warm; do not use petroleum base 5W grade oil
Engine oil	multigrade / multiviscosity	API Class CC/CD; maximum sulphated ash content 1.85 percent	-25°C to 35°C		Specifications section lists ambient ranges -13°F to 95°F (-25°C to 35°C), 14°F (-10°C) and above, and 32°F (0°C) and above; single grade oil not recommended; do not mix oils of another classification or brand
Fuel	ASTM No. 2 diesel	ASTM			Alternate diesel fuels per Cummins engine O&M Manual specifications
Fuel	Diesel				Day tank fuel transfer pump maintains reservoir of diesel fuel in the day tank.
Fuel	No. 2 diesel				Engine will also operate on No. 1 fuel or other similar fuels if they meet certain specifications
Grease	Kluber, type ASONIC GHY72			75.0 grams	P7 generator bearing re-lubrication grease fill quantity; fill period 4000-4500 hours. Must not be mixed with any other type.
Grease	Lithium based grease	Mobilux No. 2 or Shell Alvania R3		2.74 oz (81 ml)	Generator end bearing. Temperature range -22F to +248F (-30C to +120C). Grease should be equally divided between the bearing, bearing cap cavity, and bearing cartridge cavity.
Grease	Lithium based		-30°C to 120°C	81.0 ml	Mobilux No. 2 or Shell Alvania R3; generator end bearing; temperature range -22 F to +248 F (-30 C to +120 C); grease divided between bearing, bearing cap cavity and cartridge cavity.
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.
Other	Donaldsons D1400 solvent (or equivalent)				Air cleaner element cleaning: soak filter at least 15 minutes in water and Donaldsons D1400 solvent.

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	Engine operating in idle mode	Info	Remove ground from engine idle input to return to normal speed and voltage.
102	EMERGENCY STOP	Local or remote Emergency Stop activated	Shutdown	Pull button out or turn clockwise to pop out; move Run/Off/Auto switch to Off; press Reset; select Run or Auto. Reset only at PCC front panel.
121	SPEED SIGNAL LOST	Mag pickup speed indication is not being sensed.	Shutdown	Restart and check RPM on the digital display.
135	OIL PRESSURE SENSOR H	Engine oil pressure sender signal is shorted high.	Warning	Check sender/connectors/wires.
141	OIL PRESSURE SENSOR L	Engine oil pressure sender signal is shorted low.	Warning	Check sender/connectors/wires.
143	PRE-LOW OIL PRES	Engine oil pressure has dropped to an unacceptable level.	Warning	If critical loads, wait until next shutdown period and follow code 415.
144	COOL SENSOR HIGH	Engine coolant temperature signal is shorted high.	Warning	Check sender/connectors/wires.
145	COOL SENSOR LOW	Engine coolant temperature signal is shorted low.	Warning	Check sender/connectors/wires.
146	PRE-HIGH COOL TMP	Engine has begun to overheat.	Warning	Reduce load; check air inlets/outlets; follow code 151 if engine can be stopped.
151	HIGH COOLANT TEMP	Engine has overheated above the shutdown trip point.	Shutdown	Allow cool down; check coolant level, cooling airflow, fan belt, blower fan and circulation pumps.
197	LOW COOLANT LEVEL	Engine coolant level has fallen below the warning trip point.	Warning	Check coolant level and replenish if low; reset control.
200	LOW OIL PRESSURE	Engine oil pressure dropped to an unacceptable level	Warning	Follow 201 Low Oil Pressure procedure.
201	LOW OIL PRESSURE	Engine oil pressure below shutdown trip point	Shutdown	Check oil level, replenish if low, reset control and restart; contact authorized service center.
204	OIL PRES SENDER	Engine oil pressure sender not functioning correctly	Warning	Check sender connection; contact authorized service center.
210	LOW COOLANT TEMP	Engine coolant temperature 70 F (21 C) or lower	Warning	Check coolant heater power, fuse and cord; check coolant level and leaks.
211	HIGH COOLANT TEMP	Engine operating near cooling system capacity	Warning	Review 212 correction list; increase in load or higher ambient may cause shutdown.
212	HIGH COOLANT TEMP	Engine overheated; coolant above shutdown trip point	Shutdown	Cool engine; check coolant level, airflow obstructions and fan belt; reset and restart.
213	COOLANT SENDER	Resistance of coolant temperature sender out of range	Warning	Contact authorized service center.
214	LOW COOLANT LVL	Engine coolant level below trip point	Warning	Cool engine; check coolant level and leaks; reset control and restart.
215	LOW COOLANT LVL	Engine coolant level below trip point	Shutdown	Cool engine; check coolant level and leaks; reset control and restart. Shutdown will not occur in Idle mode.
220	MAG PICKUP	Mag pickup speed indication not sensed or does not match output frequency	Shutdown	Restart and check RPM on digital display; contact authorized service center.
221	FAIL TO CRANK	Possible fault with control or starting system	Shutdown	Clean and tighten battery cables; recharge or replace battery; contact service center.
222	OVERCRANK	Possible fuel system problem	Shutdown	Check fuel tank, leaks, plugged lines, fuel filter and air filter; reset control and restart.
223	OVERSPEED	Engine exceeded normal operating speed (2070 rpm @ 60 Hz; 1800 rpm @ 50 Hz)	Shutdown	Contact authorized service center.
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	Battery voltage below 24 VDC	Warning	Check battery charger fuse; recharge or replace battery; clean and tighten cable terminals.
231	HIGH DC VOLTAGE	Battery voltage exceeds 32 VDC	Warning	Contact authorized service center.
232	WEAK BATTERY	Battery voltage drops below 60% of nominal for two seconds during starting	Warning	See warning message 230 LOW DC VOLTAGE.
234	OVERSPEED	Engine has exceeded normal operating speed.	Shutdown	Check for large block load removal, flammable vapors or leaking turbocharger seals.
235	LOW COOLANT LEVEL	Engine coolant level has fallen below the shutdown trip point.	Shutdown	Check coolant level and replenish if low; reset control.
240	LOW FUEL - DAY	Day tank fuel supply running low	Warning	Check fuel supply and replenish as required.
241	LOW FUEL	Fuel supply running low	Warning	Check fuel supply and replenish as required.
250	EEPROM ERROR	PCC memory error; data corruption of critical operating parameters	Shutdown	Contact authorized service center.
251	EEPROM ERROR	PCC memory error; data corruption of noncritical operating parameters	Warning	Contact authorized service center.
252	EEPROM ERROR	PCC memory error; data corruption of noncritical operating parameters	Warning	Contact authorized service center.
260	CUSTOMER FAULT 1	Customer defined input closed to ground		Shutdown or warning preselected; message is editable; contact authorized service center.
261	GROUND FAULT	Customer defined input closed to ground		Shutdown or warning preselected; message is editable; contact authorized service center.
262	RUPTURE BASIN	Customer defined input closed to ground		Shutdown or warning preselected; message is editable; contact authorized service center.
263	HIGH GEN TEMP	Customer defined input closed to ground		Shutdown or warning preselected; message is editable; contact authorized service center.
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 110% of nominal for 10 seconds	Shutdown	Contact authorized service center.
303	LOW AC VOLTAGE	One or more phase voltages dropped below 85% of nominal for 10 seconds	Shutdown	Contact authorized service center.
313	UNDER FREQUENCY	Engine speed dropped below 90% of nominal for 10 seconds	Shutdown	Load Dump signal initiated five seconds before shutdown; contact authorized service center.
320	OVERCURRENT	Generator output current exceeded 110% of rated for 60 seconds	Warning	Contact authorized service center.
321	OVERCURRENT	Generator output current exceeded 110% of rated; PCC time/current calculation initiated shutdown	Shutdown	Contact authorized service center.
322	SHORT CIRCUIT	Generator output current exceeded 175% of rated	Shutdown	Contact authorized service center.
330	OVERLOAD	Three-phase power output exceeds 105% of standby (or 115% of prime) rating	Warning	Load Dump output activated after five seconds; warning activated after 60 seconds; contact authorized service center.
335	REVERSE POWER	Improper CT or PT phasing (non-parallel units only)	Shutdown	Contact authorized service center.
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.
359	FAIL TO START	Engine cranks but fails to start after last crank time.	Shutdown	Check fuel tank, leaks, fuel lines, fuel filter, air filter; check fuel solenoid and actuator.
415	LOW OIL PRESSURE	Engine oil pressure has dropped below the shutdown trip point.	Shutdown	Check oil level, lines and filters; replenish if low; reset control.
421	OIL TEMP	Engine oil temperature has exceeded the warning threshold.	Warning	Reduce load; check air inlets/outlets; check engine oil level.
441	LOW BAT VOLTAGE	Battery voltage supply to the control is approaching a low level.	Warning	Recharge or replace battery; check charger fuse, connections and DC alternator.
442	HIGH BAT VOLTAGE	Battery voltage supply is approaching a high level.	Warning	Check battery charger float level; check battery wiring/calibration.
1122	Rated/Idle Trans		Info
1123	SHUTDOWN AFTER BS	Shutdown fault occurred while Battle Short was enabled and then disabled.	Shutdown	Review Fault History and perform corrective action.
1124	DELAYED SHUTDOWN	Shutdown fault became active while Delayed Shutdown feature was enabled.	Warning	Review Fault History and perform corrective action.
1131	BATTLE SHORT ACTIVE	Control is in Battle Short mode.	Warning	Bypasses several critical fault shutdowns for emergency operation.
1311	Customer Input #1			Optional customer selection (e.g. Low Fuel Day Tank, Water In Fuel, Ground Fault). Programmable via service tool: enable/disable, status/warning/shutdown, active open/closed, display name.
1311, 1312, 1317, 1318	CUSTOMER INPUT #1 - #4	Optional customer-selected fault input is active.	Warning	Check external wiring and active input (closed/open) selection.
1312	Customer Input #2			See code 1311.
1313-1316	Network Fault 1 thru 4
1317	Customer Input #3			See code 1311.
1318	Customer Input #4			See code 1311.
1334	CRIT SCALER OR	Incorrect feature or calibration entered into control.	Shutdown	Reload correct calibration.
1335	NONCRIT SCALER OR	Incorrect feature or calibration entered into control.	Warning	Reload correct calibration.
1337	No Message		Info
1416	FAIL TO SHUTDOWN	Genset continues to run after shutdown command.	Warning	Check Battle Short feature enabled condition.
1417	POWER DOWN ERROR	Controller cannot power down.	Warning	Check for possible battery drain.
1433	EMERGENCY STOP	Local Emergency Stop.	Shutdown	Pull button out; move switch to O; press Fault Acknowledge/Reset; select Manual or Auto.
1434	REMOTE E-STOP	Remote Emergency Stop.	Shutdown	See code 1433 to reset.
1435	Engine Cold	Warning LED illuminates when engine jacket water coolant temperature falls below 70°F (21°C); per NFPA 110 requirement, indicates engine may not accept load within 10 seconds	Warning	Check coolant heaters for proper operation; other precautions may be necessary to warm engine before applying load
1438	FAIL TO CRANK	Engine failed to crank after PCC received a start signal.	Shutdown	Check starter, fuse F3, K4 relay, E-Stop switch and MPU circuit.
1442	WEAK BATTERY	Battery voltage at or below weak battery warning trip point during cranking.	Warning	See code 441 for corrective action.
1443	BATTERY FAILED	Dead battery - engine will not start.	Shutdown	See code 441 for corrective action.
1444	KW OVERLOAD	Generator output power exceeded 105% of genset rating.	Warning	Check load and load lead connections; check CTs.
1445	SHORT CIRCUIT	Generator output current has exceeded 175% of rated.	Shutdown	Check load and load lead connections.
1446	HIGH AC VOLTAGE	One or more phase voltages exceeded 130% of nominal.	Shutdown	Check fault simulation, load removal, threshold settings, Base board/generator.

Showing the first 80 of 133 codes.

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 adjustment

⚠ Accidental starting of the generator set during this procedure presents the hazard of severe personal injury or death. Make sure to disconnect the negative (-) battery cable(s) before beginning.

Tools: Dial indicator, Wooden shims

Disconnect the negative (-) battery cable(s) before beginning.
Fasten a dial indicator to the generator shaft or cooling fan with sensing point on capscrew head or flat surface of drive disc at 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.
Record maximum positive and negative dial indicator readings as the engine completes one revolution.
T.I.R. equals the sum of the maximum positive and negative readings.
Maximum T.I.R. should not be more than .001 inch for each inch of radius.
Remove equal shims from under both generator mounting feet to lower the generator.

Angular Alignment Procedure (750 kW gensets and larger) adjustment

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

⚠ Do not bar engine over by prying on fan blade

Tools: dial indicator

Disconnect negative battery cable(s) before beginning
Fasten dial indicator to generator shaft or cooling fan, sensing point on capscrew head or drive disc flat surface
Bar engine over in clockwise rotation as viewed from flywheel, do not allow roll-back at end of travel
Record total indicator reading (T.I.R.) as sum of max positive and negative readings over one revolution
Calculate shim correction using ratio of generator shaft-to-indicator distance vs generator mounting bolt distance
Add or remove shims from both generator mounting feet as calculated

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 (750 kW gensets and larger) adjustment

Tools: dial indicator

Check axial alignment only when objectionable vibration is present after angular alignment
Fasten dial indicator holding device to skid base/engine block/generator shell, sensor on generator shaft hub
Bar engine over clockwise through a couple of rotations, recording readings at eight equally spaced points
If out of tolerance, remove capscrews connecting drive discs and flywheel, mark discs, reposition holes 180 degrees
Reinstall capscrews and retorque; recheck alignment; try 30/60/90 degree repositioning if unchanged

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.

Gain Adjustment adjustment

Close the main line circuit breaker and apply approximately 1/4 of the rated load.
Make sure the engine speed is constant.
Turn the GAIN potentiometer clockwise slowly until the engine speed is not constant.
Slowly turn the potentiometer counterclockwise until a constant speed is achieved, then an additional 1/2 division.

Governed Speed Adjustment adjustment

For 60 Hz full load, set engine no-load governed speed to 60.0 Hz (1800 RPM) isochronous, 61.8 Hz (1854 RPM) for 3% droop, or 63.0 Hz (1890 RPM) for 5% droop.
For 50 Hz full load, set engine no-load governed speed to 50.0 Hz (1500 RPM) isochronous, 51.5 Hz (1545 RPM) for 3% droop, or 52.5 Hz (1575 RPM) for 5% droop.
Use the SPEED ADJUST potentiometer on the engine instrument panel for fine speed adjustments of less than ±100 RPM.

Governor Calibration Checks adjustment

Tools: Frequency meter or tachometer, Jumper wire

Start the generator set.
Adjust engine no-load speed to the desired allowable speed droop using the Run Speed potentiometer.
With no load, turn GAIN clockwise slowly until engine speed oscillates.
Reduce GAIN slowly counterclockwise until engine speed is stable.
Upset the governor by momentarily shorting terminals 7 and 10 on the governor control.
Apply and remove loads to check generator set response.

HC4-7 Axial Alignment Procedure adjustment

Tools: Dial indicator with magnetic base or clamp

Check only when an objectionable vibration is present.
Fasten dial indicator holding device to skid base, engine block, or generator shell with magnetic base or clamp.
Position sensor point on the generator shaft hub.
Bar the engine over in a clockwise rotation as viewed from engine flywheel through a couple of rotations.
Record indicator readings in eight equally spaced points around the shaft diameter.
Remove the capscrews connecting drive discs and flywheel and mark discs and flywheel.
Rotate engine or generator so drive disc holes are repositioned 180 degrees from original location.
Put capscrews back in and retorque. Recheck shaft alignment.
If runout unchanged, rotate discs to 30, 60 or 90 degrees from original location.
If T.I.R. does not improve, inspect flywheel pilot and drive disc runouts.

P7 Axial Alignment Procedure adjustment

Check only when an objectionable vibration is present.
Remove the capscrews connecting drive discs and flywheel.
Mark the drive discs and flywheel with respect to each other.
Rotate engine or generator so drive discs holes are repositioned two bolt holes from original location.
Put capscrews back in and retorque. Recheck/record vibration levels.
Repeat this test until drive disc holes are repositioned 180 degrees from original location.
Review vibration data and position drive disc in lowest recorded level location.

Preliminary Governor Adjustments adjustment

Idle Speed potentiometer: turn screw counterclockwise 20 turns then clockwise 10 turns to set mid position.
Run Speed potentiometer: turn screw counterclockwise 20 turns then clockwise 10 turns to set mid position.
Gain potentiometer: turn the screw fully counterclockwise.
Droop potentiometer: turn fully counterclockwise for isochronous operation; approximately 40 for 3 percent droop; approximately 80 for 5 percent droop.

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

Voltage	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	CT21 – U load leads	A phase	CT dot must face the generator; CT terminal 1 connects to metering circuit; terminal 2/3 connects to ground.
	A (U)	Bus PT module TB1 A	bus A phase	Bus PT module A39.
	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	CT22 – V load leads	B phase	CT dot must face the generator; CT terminal 1 connects to metering circuit; terminal 2/3 connects to ground.
	B (V)	Bus PT module TB1 B	bus B phase	Bus PT module A39.
	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	CT23 – W load leads	C phase	CT dot must face the generator; CT terminal 1 connects to metering circuit; terminal 2/3 connects to ground.
	C (W)	Bus PT module TB1 C	bus C phase	Bus PT module A39.
	C (W)	CT23	W load leads (C phase)	CT dot must face the generator; terminal 1 to metering circuit, terminal 2/3 to ground.
	N	Bus PT module TB1 N	bus neutral	Bus PT module A39.
110 V - 120 V L-N	1	Single phase, 2-wire		PTC module jumper locations
190 V - 240 V L-L	3	Three phase		Use PTC module 0300-5382-01; 50/60 Hz
200 V - 240 V L-L	1	Single phase, 3-wire		PTC module jumper locations
380 V - 600 V L-L	3	Three phase		Use PTC module 0300-5382-02; 50/60 Hz
high voltage genset		12-lead CT secondary wire marked 2/3 to pin 2	2/3	For high voltage gensets.
low voltage genset		12-lead CT secondary wire marked 2/3 to pin 3	2/3	For low voltage gensets.

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 KTTA50 family

Part #	Description	Category
140-2503	Bracket, Mounting	Air filter
140-3163	Cleaner, Air (No Replaceable Element)	Air filter
140-3230	Cleaner, Air (Includes Elements - See Ref. No. 25 and 26)	Air filter
0300-4623-33	DFLE (600V)	Current transformer
0300-4623-57	DFLE BR (0-480V)	Current transformer
140-1260	Fitting, Safety Filter	Service part / kit
140-2395	Tube, Air Inlet	Service part / kit
140-2504-01	Bracket - Right Side	Service part / kit
140-2504-02	Bracket - Left Side	Service part / kit
140-2509	Tube, Air Inlet	Service part / kit
140-2528	Shield – Air In Heat	Service part / kit

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

Common questions

What is the oil capacity of the Cummins/Onan KTTA50?

The Cummins/Onan KTTA50 engine has an oil capacity of 169.0 liters.

Which generators use the Cummins/Onan KTTA50 engine?

The Cummins/Onan KTTA50 powers 2 generator set(s), including Cummins/Onan DFLC, Cummins/Onan DFLE.

What is a common problem with the Cummins/Onan KTTA50 engine?

A commonly reported issue on generators using the Cummins/Onan KTTA50 is: Engine cranks but fails to start. Cause: Empty fuel tank, fuel leaks, or plugged fuel lines. Fix: Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required..

Cummins/Onan KTTA50 Engine

Engine specifications

Generator sets powered by this engine

Common problems

Repair guides

Service intervals

Service specifications

Recommended fluids

Fault codes

Procedures

Voltage reconnection

Parts cataloged across the Cummins/Onan KTTA50 family

Common questions