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Cummins/Onan KTTA50 Engine

Name: Cummins/Onan KTTA50 Engine
Brand: Cummins/Onan

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 — 2 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

Warning Status Indicator: This yellow lamp is lit whenever the control detects a warning condition.
Fix: After the condition is corrected, warning indicators can be reset by pressing the Reset switch. (It is not necessary to stop the generator set.) In auto mode, warning indicators can also be reset by cycling the remote reset input after the condition is corrected.
Warning lamp lights. 210
Fix: Indicates set is in standby mode but is not operating. Warning occurs when engine coolant temperature is 70 F (21 C) or lower. NOTE: In applications where the ambient temperature falls below 40F (4C), Low Engine Temp may be indicated even though the coolant heaters are operating. Indicates engine coolant heater is not operating or is not circulating coolant. Check for the following conditions: a. Coolant heater not connected to power supply. Check for blown fuse or disconnected heater cord and correct as required. b. Check for low coolant level and replenish if required. Look for possible coolant leakage points and repair as required. c. Contact an authorized service center if none of the above.
Shutdown Status Indicator: This red lamp is lit whenever the control detects a shutdown condition.
Fix: After the condition is corrected, shutdown indicators can be reset by turning
Shutdown lamp lights. 200
Fix: Indicates engine oil pressure has dropped to an unacceptable level. If generator is powering critical loads and cannot be shut down, wait until next shutdown period then follow 201 Low Oil Pressure procedure. If engine can be stopped, follow 201 procedure. To check oil pressure, access Oil Pressure menu prior to clearing the fault.
PCC memory error. Data corruption of noncritical operating parameters. Warning lamp lights. 251
Fix: Contact an authorized service center.
PCC memory error. Data corruption of critical operating parameters. Shutdown lamp lights. 250
Fix: Contact an authorized service center.
One or more of the phase voltages has exceeded 130% of nominal, or has exceeded 110% of nominal for 10 seconds. Shutdown lamp lights. 301
Fix: Contact an authorized service center.
Non-Automatic lamp flashes.
Fix: Indicates Run/Off/Auto switch is not in the Auto position. This will prevent automatic starting if an automatic transfer switch is used. Move the Run/Off/Auto switch to the Auto position for automatic operation.
Indicates engine coolant level has fallen below the trip point. Shutdown lamp lights. 220
Fix: A. Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary. b. Reset control and restart after locating and correcting problem. Contact an authorized service center.
Fuel supply is running low. Warning lamp lights. 241
Fix: Check fuel supply and replenish as required.
Engine will not crank. Shutdown lamp lights. 221
Fix: A. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. b. Discharged or defective battery. Recharge or replace the battery. c. Contact an authorized service center for service of starter and starting system.
Engine stops cranking. Shutdown lamp lights. 222
Fix: A. Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. b. Check for dirty fuel filter and replace if necessary. c. Check for dirty or plugged air filter and replace if necessary. d. Reset the control and restart after correcting the problem. Contact an authorized service center if none of the above.
Engine shuts down and will not crank. 102
Fix: Indicates local or remote Emergency Stop. To reset the local Emergency Stop button: Pull the button out or turn the switch clockwise (button with arrow) and allow it to pop out. Move the Run/Off/Auto switch to Off. Press the Reset switch. Select Run or Auto, as required.
Engine runs and then shuts down. Shutdown lamp lights. 223
Fix: Contact an authorized service center.
Engine continues to operate at reduced RPM. 101

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
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	1	inch (25 mm) minimum	when cleaning with compressed air
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
Other	AVR Droop setting	5	% at full load, 0 PF
Other	AVR voltage regulation (load regulation)	approximately ±0.5	% RMS
Other	B+ output fuse	10	amp	F1, Base board, 12/24 volt
Other	Battery charging current	45	Amps
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	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	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	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 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 limit (Detector, optional)	75	seconds
Other	REG VHZ (underfrequency roll-off) adjustable range	1 through 50; normal range 7 through 21
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
Pressure	Air cleaner cleaning compressed air pressure	30	psi (207 kPa)	blow through element from clean side
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
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	Idle oil pressure (PCC)	20	psi (138 kPa)	idle
Pressure	Idle oil pressure - shutdown limit	10	psi (69 kPa)	idle oil pressure table, label order uncertain from source table layout
Pressure	Idle oil pressure - value 1	20	psi (138 kPa)	idle oil pressure table, label order uncertain from source table layout
Pressure	Idle oil pressure - warning limit	15	psi (103 kPa)	idle oil pressure table, label order uncertain from source table layout
Pressure	Idle oil pressure shutdown limit (PCC)	10	psi (69 kPa)	idle
Pressure	Idle oil pressure warning limit (PCC)	15	psi (103 kPa)	idle
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

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	Water/antifreeze mixture (permanent type antifreeze)				Water should be clean, low in mineral content, free of chloride, sulphate or acid; mix per supplier for lowest expected ambient temperature; do not use antifreeze containing anti-leak additives
Coolant	soft water / E.G. / DCA mixture				Cooling system to be filled with soft water/E.G./DCA mixture (on-site review checklist).
Engine oil		API Class CC/CD, maximum sulphated ash content 1.85 percent			Multigrade/multiviscosity oils recommended; single grade oil not recommended; do not mix oils of different classification or brand
Engine oil	SAE 5W synthetic	API class CC/CD; sulphated ash not to exceed 1.85 percent	below -25°C		For ambient temperature consistently below -30 deg F (-25 deg C) with no provision to keep engine warm; pour point 9 deg F (5 deg C) below lowest expected temperature; viscosity max 10,000 mPa.s at -31 deg F (-35 deg C) and min 4.1 mm2/s at 212 deg F (100 deg C); do not use petroleum base 5W grade oil
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 similar fuels if they meet specifications; consult engine manufacturer for non-standard fuel
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		-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	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	Local or remote Emergency Stop activated	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.
1122	Rated/Idle Trans		Info
1123	Shutdown After Battle Short	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 Sh Active	Control is in Battle Short mode.	Warning	Bypasses several critical fault shutdowns for emergency operation.
121	Speed Signal Lost	Mag pickup speed indication is not being sensed.	Shutdown	Restart and check RPM on the digital display.
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 Out Of Range	Incorrect feature or calibration entered into control.	Shutdown	Reload correct calibration.
1335	Noncrit Scaler Out Of Range	Incorrect feature or calibration entered into control.	Warning	Reload correct calibration.
1337	No Message		Info
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.
1416	Fail To Shutdown	Genset continues to run after shutdown command.	Warning	Check Battle Short feature enabled condition.
1417	Powr Down Error	Controller cannot power down.	Warning	Controller cannot power down; possible drain on battery. Contact an authorized service center.
143	Pre-Low Oil Pres	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 code 415 procedure.
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	Low Coolant Temp	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	Set is not operating; occurs when coolant temperature is 70°F (21°C) or lower. Check coolant heater power/fuse/cord, check coolant level and leaks.
1438	Fail To Crank	Engine failed to crank after PCC received a start signal.	Shutdown	Possible fault with control, speed sensing, or starting system. See code 441 for corrective action.
144	Coolant Sensor High	Engine coolant temperature signal is shorted high.	Warning	Check sender/connectors/wires.
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.
1447	Low AC Voltage	Phase voltages dropped below 85% of nominal for 10 seconds.	Shutdown	Check overload, output terminal connections, PMG/field wiring, rectifier diodes.
1448	Under Frequency	Engine speed dropped below 90% of nominal for 10 seconds.	Shutdown	Check fuel supply, intake air supply and load.
1449	Over Frequency	Frequency is 10% above base frequency for 20 seconds.	Warning	Check fuel or air delivery; check connections.
145	Coolant Sensor Low	Engine coolant temperature signal is shorted low.	Warning	Check sender/connectors/wires.
1452	Gen CB Not Close	Genset circuit breaker (S2) failed to close when PTC is enabled.	Warning	Refer to Section 5 troubleshooting charts.
1453	Gen CB Not Open	Genset circuit breaker (S2) failed to open when PTC is enabled.	Warning	Refer to Section 5 troubleshooting charts.
1459	Reverse Power	Improper CT phasing.	Shutdown	Check wiring to voltage sense circuit; refer to CT Installation in Section 6.
146	Pre-High Coolant Temp	Engine has begun to overheat.	Warning	Reduce load; check air inlets/outlets; follow code 151 if engine can be stopped.
1461	Loss Of Field	Loss of field (electric) due to reverse kVAR.	Shutdown	Check excitation circuit.
1466	Modem Failure	Control cannot communicate with the modem.	Warning	Check for open, short to ground and loose connections to the modem.
1468	Network Error	Momentary loss of communication from the LonWorks Network.	Warning	Refer to LonWorks Network publications.
1469	Speed/Hz Match	Measured speed and measured AC output frequency do not agree.	Shutdown	Check calibration file.
1471	Over Current	Generator output current exceeded 110% of rated for 60 seconds.	Warning	Check load and load lead connections.
1472	Over Current	Output current exceeded 110% of rated and time/current calculation initiated shutdown.	Shutdown	Check load and load lead connections.
151	High Coolant Temp	Engine has overheated above the shutdown trip point.	Shutdown	Allow engine to cool completely. Check coolant level and replenish if low, look for leaks and repair. Check for obstructions to cooling airflow. Check fan belt. Check blower fan/circulation pumps on remote radiator installations. Reset control and restart.
197	Low Coolant Level	Engine coolant level has fallen below the warning trip point.	Warning	Optional. If generator is powering critical loads and cannot be shut down, wait until next shutdown period, then follow code 235 procedure. If engine can be stopped, follow code 235 procedure.
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, replenish if low, reset control and restart; contact authorized service center.
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	Review 212 correction list; increase in load or higher ambient may cause shutdown.
212	Oil Temp Sensor H	Indicates engine has overheated (coolant temperature above 215° F (102° C) − standby or 207° F (97° C) − primary).	Warning	Cool engine; check coolant level, airflow obstructions and fan belt; reset and restart.
213	Oil Temp Sensor L	Resistance of the coolant temperature sender is out of range.	Warning	Contact authorized service center.
214	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point.	Warning	Cool engine; check coolant level and leaks; reset control and restart.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the 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; check PCC model setting; inspect and test MPU.
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	Indicates engine has exceeded normal operating speed. (115% ±1% of nominal).	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	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 warning message 230 LOW DC VOLTAGE.
2323-2326	Network Fault 5 thru 8
2327	PTC Fault	PTC module or communication link is not working properly.	Warning	Check PTC module power, ground shield, cycle control power.
2329	Low S1 Frequency	Low utility (S1) frequency.	Warning	Check S1 AC inputs and wiring to PTC at TB5; check sensor set points.
2331	Low S1 Voltage	Low utility (S1) voltage.	Warning	Check S1 AC inputs and wiring to PTC at TB5; check pickup/dropout set points.
2335	Excitation Fault	Loss of all three voltage sense leads or failure in excitation circuit.	Shutdown	Check field wiring (X1 and X2) for shorts or opens.
2336	Memory Error	Control memory error; data corruption of critical operating parameters.	Shutdown	Try reloading calibration file.
2337	Pwr Tran Disabled	PTC module available but PTC feature not enabled.	Warning	Enable PTC feature with InPower; cycle control power.
2338	Pwr Tran Failure	Control could not communicate with the PTC module.	Warning	Check PTC module power and cable ground shield; cycle control power.
2339	Pwr Down Enabled	Power Down (sleep) enabled but PTC module or network board is active.	Warning	None required.
234	Overspeed	Engine has exceeded normal operating speed.	Shutdown	Check for large block load removal, flammable vapors or leaking turbocharger seals.
2341	High Control Temp	Control temperature above 158 F (70 C) for longer than set time.	Warning	Check genset room air flow.
2342	Too Long In Idle (10 min.)	Genset has been in Idle mode too long.	Warning	Exit idle mode.
235	Low Coolant Level	Engine coolant level has fallen below the shutdown trip point.	Shutdown	Optional. Allow engine to cool completely. Check coolant level and replenish if low, look for leaks and repair. Reset control and restart.
2358	High S1 Voltage	Utility (S1) voltage increased above the over-voltage threshold.	Warning	Measure S1 AC inputs at PTC module; check sensor set points.
2396	S1 CB Not Close	Utility contact (S1) failed to close with PTC enabled.	Warning	Refer to Section 5 troubleshooting charts.

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 (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.

Electric Governor Preliminary Adjustments adjustment

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

Fine Speed Adjustment adjustment

After the gain adjustment is made, adjust full load governed engine speed to equal the desired speed (60 Hz, 1800 RPM or 50 Hz, 1500 RPM).
Use the SPEED ADJUST potentiometer on the engine instrument panel for fine speed adjustments of less than +/-100 RPM.

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. If 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.
Turn the potentiometer counterclockwise an additional 1/2 division.

Generator/Base Board Isolation Procedure diagnostic

⚠ This test involves unregulated excitation of the generator.

⚠ Hazardous voltage; use insulated tools and stand on dry platform.

Tools: Voltmeter, Jumper leads, 12V battery

Throw line circuit breaker OFF and shut down the set.
Disconnect exciter stator leads X and XX from AC harness.
Prepare to measure output voltage across generator terminals.
Bring 12V battery jumpers to X (Field +) and XX (Field -).
Verify polarity is correct before connecting.
Start set; connect battery negative to XX lead.
If rated voltage and balanced phases, generator is OK.
If unbalanced troubleshoot main stator; if low troubleshoot exciter circuits.

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.

Ground Fault Relay Test diagnostic

Verify N-G Fault Indicator on GFR is not lit; if lit, install bonding jumper at facility service entrance
Move control switch to Run position
Press TEST switch on ground fault relay
Verify control panel warning message displayed and Fault Indicator (>I) lit on GFR
Reset the control panel fault (also resets ground fault relay)

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.

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 (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.
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

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	other_service
140-2395	Tube, Air Inlet	other_service
140-2504-01	Bracket - Right Side	other_service
140-2504-02	Bracket - Left Side	other_service
140-2509	Tube, Air Inlet	other_service
140-2528	Shield	other_service

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: Warning Status Indicator: This yellow lamp is lit whenever the control detects a warning condition.. Fix: After the condition is corrected, warning indicators can be reset by pressing the Reset switch. (It is not necessary to stop the generator set.) In auto mode, warning indicators can also be reset by cycling the remote reset input after the condition is corrected..