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Cummins/Onan 6BTA5.9 Engine

Name: Cummins/Onan 6BTA5.9 Engine
Brand: Cummins/Onan

The Cummins/Onan 6BTA5.9 is a 5.9 L 6-cylinder engine. It powers generator sets from Cummins/Onan, including the DGDK. It holds 16 L (4.2 gal) of oil and 31.5 L (8.3 gal) of coolant.

Also known as: Cummins 6BTA5.9

Part of the Cummins/Onan 6BTA5.9 engine family — 10 variants share parts & fitment.

5.9 L

Displacement

Cylinders

16.0 L

Oil capacity

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

Engine specifications

Oil capacity	16.0 L
Coolant capacity	31.5 L
Displacement	5.9 L
Cylinders	6

Generator sets powered by this engine

Cummins/Onan DGDK

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

Common problems

Over Current 1471
Low Coolant Level 197
Weak Battery 1442
Under Frequency 1448
Too Long in Idle 2342
Status Indicators Fault Code Table
Speed/Hz Match 1469
Speed Signal Lost 121
Shutdown After Battle Short 1123
Short Circuit 1445
Remote Emergency Stop 1434
Pre-Low Oil Pressure Sensor 143
Pre-High Cool Temp 146
Power Down Failure 1417
Overspeed 234

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan 6BTA5.9.

Service intervals

Item	Action	Hours	Months	Notes
Coolant Heater	Check	50 hr		Verify hot coolant is being discharged from the outlet hose.
Coolant Level	Check	8 hr
Coolant Level (Recovery Tank)	Check	8 hr		Table 5-1
Exhaust Condensate Trap	Drain	8 hr		Table 5-1
Fuel Level	Check	8 hr		Table 5-1
Fuel Tanks (water and sediment)	Drain	8 hr		Drain 1 cup or more of fuel to remove water and sediment.
General Genset Inspection	Inspect	8 hr		Table 5-1; also indicated for weekly/50 hours (X1, X2)
Inspect Genset	Check	8 hr		Check for oil, fuel, cooling and exhaust system leaks. Check exhaust system audibly and visually with set running and repair any leaks immediately.
Oil Level	Check	8 hr		Table 5-1
Water and Sediment from Fuel Tank	Drain	8 hr		Table 5-1; drain 1 cup or more of fuel to remove water and sediment
Air Cleaner	Clean	50 hr		Table 5-1; X3 perform more often in dusty conditions
Battery Charging System	Check	50 hr		Table 5-1
Charge Air Piping	Check	50 hr		Table 5-1
Crankcase Oil	Drain	50 hr		First service — Break-in: drain and replace the crankcase oil after the first 50 hours of operation on new generator sets.
Starting Batteries	Check	50 hr		Table 5-1
Battery Electrolyte Level	Check	200 hr		Check at least every 200 hours of operation; disregard for maintenance-free battery
Air Cleaner Element	Change	500 hr	6 mo	Table 5-1; replace yearly or sooner if service indicator button pops up
Anti-freeze and DCA Concentration	Check	250 hr	6 mo	Table 5-1
Coolant Filter	Change	500 hr	6 mo	Table 5-1
Cooling System	Clean	500 hr	6 mo	Table 5-1
Crankcase Breather	Clean	500 hr	6 mo	Table 5-1
Crankcase Oil and Filter	Change	250 hr	12 mo	Table 5-1 X6: if genset is used for standby applications, change oil every 12 months or 250 hours, whichever comes first
Drive Belt Tension	Check	250 hr	6 mo	Visually check belt for evidence of wear or slippage. Replace if hard or brittle. Refer to engine operation and maintenance manual.
Fuel Filter(s)	Drain	250 hr	6 mo	Table 5-1
Fuel Filters	Change	250 hr	6 mo	Table 5-1
Governor Adjustment	Check	250 hr	3 mo
Radiator Hoses for Wear & Cracks	Check	250 hr	6 mo	Table 5-1
Valve Lash	Adjust	1000 hr		Table 5-1: after 1000 hours; contact an authorized service center for service
Generator Set Exercise	Test		1 mo	Exercise the generator set at least once a month for a minimum of 30 minutes, under not less than 30 percent of the nameplate rating

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	Clearance around generator set for maintenance and service access	1	meter (3 feet)
Clearance	Exhaust pipe clearance from combustible wall or partition	12	inches (305 mm)	minimum
Clearance	Float switch lift below C-clip stop	1/8	inch (3 mm)
Clearance	Fuel line clearance from electrical wiring	1/2	inch (12.7 mm)	minimum
Clearance	Fuel line clearance from hot exhaust parts	2	inch (51 mm)	minimum
Clearance	Vibration isolator base elevation (max difference between isolator bases)	0.25	inch (6 mm)
Clearance	Vibration isolator top plate to base clearance	0.25	inch (6 mm)	nominal, minimum
Other	Battery electrolyte corrected specific gravity (fully charged)	1.260		electrolyte temperature corrected
Other	Battery electrolyte specific gravity (fully charged)	1.260	specific gravity	corrected to 80 F (27 C)
Other	Battery electrolyte specific gravity charge threshold	1.215	specific gravity	charge battery if reading is below this value
Other	Battery recharge threshold specific gravity	1.215
Other	Battery specific gravity temperature correction	four gravity points (0.004) for every ten degrees above 80 F (27 C)
Other	Cool-down at idle	0−30	min
Other	Customer output relay contacts rating (TB1 outputs 1-4)	2	amps at 30 VDC	normally open contacts
Other	Cycle crank crank and rest time	7 to 20	seconds
Other	Cycle crank number of cycles	3, 4, or 5
Other	Default start cycles	3	cycles	15 seconds of cranking and 15 seconds of rest
Other	Frequency Adjust range	5	percent of nominal frequency	e.g. 60.0 Hz adjustable 57.0 to 63.0 Hz
Other	Frequency adjustment range	±5%	%	genset running
Other	Fuse A31-F1 (control B+)	5	Amp	Engine Interface board
Other	Fuse A31-F3 (auxiliary B+)	5	Amp	Engine Interface board; panel lights, run and start relays
Other	Fuse A38-F1 (Network B+)	10	Amp	Governor Output Module
Other	Fuse A38-F2 (Switched B+)	10	Amp	Governor Output Module
Other	Fuse A38-F3 (Governor B+)	10	Amp	Governor Output Module
Other	Fuse TB-Bat F1 (Customer B+)	20	Amp	Engine Harness Assembly
Other	GOV RAMP adjustment range	0 through 10	seconds
Other	Low oil pressure / high engine temperature fault time delay	about 10	seconds	following starter disconnect and inhibited during cranking
Other	Mounting bolts used to secure vibration isolators to base	5/8 inch or 16 mm		anchored mounting bolts
Other	Optional control relay (K11, K12, K13) contacts rating	10	amps at 600 VAC
Other	Overcrank limit (Sentinel)	60	seconds
Other	Overcrank option limit (Detector)	75	seconds
Other	REG VHZ adjustment range	1 through 50 (normal range 7 through 21)
Other	Rated To Idle delay	0−10	sec	Beginning Version 2.303; default = 0
Other	Setup/calibration menu access code	574
Other	Specific gravity correction factor	0.004	gravity points	per 10 degrees electrolyte temperature above 80 F (27 C)
Other	Standard cycle cranking (Detector)	three 15-second cranking cycles with two 15-second rest periods
Other	Start delay adjustment range	0 to 300	seconds	remote starting in Auto mode
Other	Stop delay adjustment range	0 to 600	seconds	remote stopping in Auto mode
Other	Time Delay To Start	0−300	sec	default = 0
Other	Time Delay To Stop (Stop Delay)	0−600	sec	default = 0
Other	Voltage adjustment range	±5%	%	genset running
Other	Warm-up at idle time delay	0−300	sec	manual mode
Pressure	Engine Oil Pressure (Normal)	276-483	kPa	normal operating
Pressure	Engine Oil Pressure (Normal)	40-70	psi	normal operating
Pressure	Engine oil pressure (normal)	30 to 65	psi (207 to 449 kPa)	at normal operating temperature
Pressure	Engine oil pressure range (low oil pressure troubleshooting)	25 to 65	psi (172 to 449 kPa)
Pressure	Fuel shutoff valve rating (TB1-8 and TB1-5)	not more than 0.5	amps	120 or 240 VAC
Pressure	Idle Oil Pressure	10-30	psi	idle
Pressure	Idle Oil Pressure	69-207	kPa	idle
Pressure	Idle Oil Pressure Shutdown Limit	55	kPa	idle
Pressure	Idle Oil Pressure Shutdown Limit	8	psi	idle
Pressure	Idle Oil Pressure Warning Limit	12	psi	idle
Pressure	Idle Oil Pressure Warning Limit	83	kPa	idle
Pressure	Idle oil pressure	10 - 30	psi (69 - 207 kPa)	idle
Pressure	Idle oil pressure (normal)	10-30	psi (69-207 kPa)	Engine model 6C, idle
Pressure	Low oil pressure shutdown limit	14	psi (97 kPa)
Pressure	Maximum allowable exhaust back pressure	41	in. H2O
Pressure	Maximum fuel inlet restriction	4	in. Hg. (13.5 kPa)
Pressure	Maximum fuel return restriction	20	in. Hg. (67.6 kPa)
Pressure	Maximum radiator cleaning air/water pressure	242	kPa	cleaning radiator fins

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	Capacity	Notes
Coolant		Refer to the Cummins engine Operation and Maintenance Manual for coolant recommendations/specifications	25.0 L	Capacity with standard radiator 6.5 Gal (25 L) DGDA/DGDB; 8.3 Gal (31.5 L) DGDK; heavy duty diesel engines require a balanced coolant mixture of water, antifreeze and coolant additives
Coolant	50/50 mix of water and antifreeze	Balanced coolant mixture of water, antifreeze and coolant additives		Drain and replace the mixture every 6 months or after 500 hours of operation. Do not add cold coolant to a hot engine; allow engine to cool below 120 F (50 C) before adding coolant.
Engine oil		Refer to Cummins engine Operation and Maintenance Manual for lubricating oil recommendations/specifications	16.0 L	Oil capacity with filters 17 Qts (16 L); gensets are shipped with oil added
Fuel	ASTM No. 2 diesel fuel			Cummins engines normally use ASTM No. 2 diesel fuel; will operate on alternate diesel fuels within specifications in Cummins engine Operation and Maintenance Manual.
Fuel	diesel			Do not use zinc coated or copper fuel lines with diesel fuel.

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; generator build-up is inhibited and engine governed at 800 RPM.	Warning	Remove ground from the engine idle input to return to normal speed and voltage.
102	EMERGENCY STOP	Indicates local or remote Emergency Stop.	Shutdown	Pull the button out; move the Run/Off/Auto switch to Off; press the Reset switch; select Run or Auto as required. Can only be reset at the PCC front panel.
1122	Rated/Idle Trans	Rated/Idle transition	Info
1123	Shutdown After Battle Short	Shutdown after Battle Short	Shutdown	Review Fault History and perform corrective action.
1124	Delayed Shutdown	Delayed shutdown	Warning	Review Fault History and perform corrective action.
1131	Battle Sh Active	Control is in Battle Short mode (bypasses several critical fault shutdowns).	Warning	When Battle Short mode is enabled, the Warning status indicator is lit along with displayed fault code 1131. Refer to Battle Short Mode description in Section 3.
121	Speed Signal Lost	Speed signal lost	Shutdown	Restart and check RPM on digital display; inspect MPU wires/connector pins; check for 3.5 to 15 VAC at MPU while cranking.
1311	Customer Input #1	Customer input #1 (optional customer selection)		Programmable (service tool): enable/disable input (default enable); status, warning or shutdown (default #1 = None); active closed or open (default closed [ground]); change display name up to 19 characters.
1311, 1312, 1317, 1318	CUSTOMER INPUT #1 - #4	Optional customer-selected fault input is active.		Disconnect signal lead from TB1 and reset the control; check external wiring/active input selection.
1312	Customer Input #2	Customer input #2 (optional customer selection)		Programmable (service tool): enable/disable input (default enable); status, warning or shutdown (default #2 = Warning); active closed or open (default closed [ground]); change display name.
1313−1316	Network Fault 1 thru 4	Network fault 1 through 4
1317	Customer Input #3	Customer input #3 (optional customer selection)		Programmable (service tool): enable/disable input; status, warning or shutdown; active closed or open; change display name.
1318	Customer Input #4	Customer input #4 (optional customer selection)		Programmable (service tool): enable/disable input; status, warning or shutdown; active closed or open; change display name.
1334	Crit Scaler Out Of Range	Incorrect feature or calibration was entered into control.	Shutdown	Reload correct feature/calibration file.
1335	Noncrit Scaler Out Of Range	Non-critical scaler out of range	Warning	Reload correct feature/calibration file.
1337	No Message	No message	Info
135	Oil Pressure Sensor H	Oil pressure sensor high	Warning	Check sender/connectors/wires; verify fault simulation not enabled; check 0.5 to 4.5 VDC at P7-13 (OP OUT) and P7-17 (OP COM).
141	Oil Pressure Sensor L	Oil pressure sensor low	Warning	Check sender/connectors/wires; check for shorts/open circuits at P7-13, 17, 21.
1416	Fail To Shutdown	Genset continues to run after receiving shutdown command (Battle Short feature enabled).	Warning	Refer to Battle Short Mode description in Section 3.
1417	Powr Down Error	The controller cannot power down because of some unknown condition; possible drain on battery	Warning	Contact an authorized service center for service.
143	Pre-Low Oil Pres	Engine oil pressure has dropped below the warning trip point	Warning	If generator is powering critical loads and cannot be shut down, wait until the next shutdown period and then follow code 415 procedure.
1433	Emergency Stop	Local Emergency Stop.	Shutdown	Pull the 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	Initiates a warning when the engine jacket water coolant temperature falls below 70 deg F (21 deg C); provided to meet NFPA 110 requirements, in conjunction with illumination of the Warning LED.	Warning	Indicates engine coolant heater is not operating or is not circulating coolant. Check coolant heater connection to power supply: check for blown fuse or disconnected heater cord and correct. Check for low coolant level and replenish if required; look for possible coolant leaks and repair.
1438	Fail To Crank	Possible fault with control, speed sensing or starting system	Shutdown	Test for B+ at the starter; check fuse F3 (2 Amps); check K4 start pilot relay and starter circuitry; refer to code 121.
144	Coolant Sensor High	Engine coolant temperature signal is shorted high.	Warning	Check sender/connectors/wires; check resistance between P7-30 (IH20) and P7-34 (IH20 COM).
1442	Weak Battery	During cranking, battery voltage is at or below the weak battery warning trip point for a time greater than or equal to the weak battery set time	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	kW overload	Warning	Check load and load lead connections; check CTs and CT connections.
1445	Short Circuit	Short circuit	Shutdown	Check load and load lead connections (fault may not reset for several minutes).
1446	High AC Voltage	Phase voltage exceeded 130% of nominal, or 110% of nominal for 10 seconds.	Shutdown	Check fault simulation; clear fault and restart; refer to Generator/Base Board Isolation Procedure.
1447	Low AC Voltage	Phase voltage dropped below 85% of nominal for 10 seconds.	Shutdown	Check load; reconnect per reconnection diagram; check PMG/field wiring; check P8-21/P8-22 shunt connections.
1448	Under Frequency	Under frequency	Shutdown	Check fuel supply, intake air supply and load; check P8 connections.
1449	Over Frequency	Over frequency	Warning	Check fuel or air delivery problem; repair P7/P8 connections.
145	Coolant Sensor Low	Engine coolant temperature signal is shorted low.	Warning	Check sender/connectors/wires; check for shorts at P7-30 and P7-34.
1452	Gen CB Not Close	Genset circuit breaker (S2) failed to close when PTC enabled.	Warning	Refer to Section 5.
1453	Gen CB Not Open	Genset circuit breaker (S2) failed to open when PTC enabled.	Warning	Refer to Section 5.
1459	Reverse Power	Reverse power	Shutdown	Check wiring to voltage sense circuit; refer to CT Installation in Section 6.
146	Pre-High Coolant Temp	Engine is operating near cooling system capacity	Warning	Reduce load; check air inlets/outlets and remove obstructions to airflow; if engine can be stopped follow code 151.
1461	Loss Of Field	Loss of field (electric) due to reverse kVAR.	Shutdown	Check field circuit.
1466	Modem Failure	Modem failure	Warning	Check for open, short circuit to ground, and loose connections to the modem.
1468	Network Error	Network error	Warning	Refer to the LonWorks Network publications.
1469	Speed/Hz Match	Speed/Hz match	Shutdown	Check calibration file.
1471	Over Current	Over current	Warning	Check load and load lead connections.
1472	Over Current	Over current	Shutdown	Check load and load lead connections (fault may not reset for several minutes).
151	High Coolant Temp	Engine has overheated (coolant temperature has risen above the shutdown trip point)	Shutdown	Allow engine to cool; check coolant level; check airflow obstructions; check fan belt; check blower fan/remote radiator pumps; reset control and restart.
197	Low Coolant Level	Engine coolant level has fallen below the warning trip point.	Warning	If generator is powering critical loads and cannot be shut down, wait until next shutdown period, then follow code 235 procedure.
200	LOW OIL PRESSURE	Indicates engine oil pressure has dropped to an unacceptable level.	Warning	If powering critical loads, wait until next shutdown period and follow 201-SHUTDOWN procedure; check oil pressure via menu prior to clearing 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. Oil pressure limits in Table 4-3.
204	OIL PRESS SENDER	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, indicating the engine coolant heater is not operating or is not circulating coolant.	Warning	Check coolant heater power supply, fuse or disconnected heater cord; check for low coolant level and replenish; check for an open heater element by checking current draw of heater.
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) prime.	Warning	Reduce load if possible; check air inlets/outlets; follow 212-SHUTDOWN procedure if engine can be stopped.
212	Oil Temp Sensor H	Oil temperature sensor high	Warning	Check sender/connectors/wires; check resistance between P7-22 (OIL TEMP) and P7-26 (OIL TEMP COM).
213	Oil Temp Sensor L	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; look for leakage; reset control and restart.
215	LOW COOLANT LVL	Indicates engine coolant level has fallen below the trip point. LOW COOLANT LVL Shutdown will not occur if genset is in Idle mode (low coolant warning only).	Shutdown	Check coolant level in radiator and bottle; check coolant bottle hose or radiator cap; 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 on the digital display; inspect/adjust MPU.
221	FAIL TO CRANK	Possible fault with control or starting system; engine will not crank.	Shutdown	Check fuse F3 on the Engine Interface board; check for poor battery cable connections; recharge or replace a discharged or defective battery.
222	OVERCRANK	Possible fuel system problem; engine stops cranking.	Shutdown	Check for empty fuel tank, fuel leaks, or plugged fuel lines; check/replace dirty fuel filter and air filter; reset and restart.
223	OVERSPEED	Indicates engine has exceeded normal operating speed (115% ±1% of nominal).	Shutdown	Inspect the mechanical fuel linkage and repair or replace; check the EFC for binding or damage; monitor the PCC duty cycle display and replace A32 or A38 as indicated.
230	LOW DC VOLTAGE	Indicates battery voltage is below 10 VDC.	Warning	Recharge or replace battery; clean/tighten connections; check engine DC alternator; check battery charger float level.
231	HIGH DC VOLTAGE	Indicates battery voltage exceeds 32 VDC.	Warning	Check voltage float level on battery charger if applicable (lower float level); check engine DC alternator and replace if normal battery charging voltage is not obtained.
232	WEAK BATTERY	Indicates battery voltage drops below 60% of nominal for two seconds, during starting.	Warning	Recharge or replace the battery; see 230 LOW DC VOLTAGE.
2323−2326	Network Fault 5 thru 8	Network fault 5 through 8
2327	PTC Fault	PTC module or communication link not working properly when PTC enabled.	Warning	Check blinking light on PTC module; check B+ TB3-3 to TB3-4; check PTC status voltage TB3-5 to TB3-6 (~0.2 VDC); repower control.
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	Repower PCC 2100 control to clear; check S1 AC inputs at TB5; check S1 pickup/dropout set points.
2335	Excitation Fault	Loss of all three voltage sense leads or failure in excitation circuit.	Shutdown	Critical shutdown fault; suspends Battle Short and shuts down immediately.
2336	Memory Error	Memory error	Shutdown	Try reloading calibration file.
2337	Pwr Tran Disabled	Power transfer disabled	Warning	Use InPower to enable PTC feature; cycle power off for 5 seconds then repower.
2338	Pwr Tran Failure	Power transfer failure	Warning	Check blinking light and B+ TB3-3 to TB3-4; check connections between TB2 and TB3; cycle power.
2339	Pwr Down Enabled	Power down enabled	Warning	None required.
234	Overspeed	Overspeed shutdown	Shutdown	Critical shutdown fault; suspends Battle Short and shuts down immediately.
2341	High Control Temp	High control temperature	Warning	Check genset room air flow.
2342	Too Long In Idle	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	Check coolant level and replenish; look for leaks; reset control and restart.
2358	High S1 Voltage	Utility (S1) voltage increased above over voltage threshold.	Warning	Measure S1 AC inputs at PTC module; check utility nominal voltage; check sensor set points.
2396	S1 CB Not Close	Utility contact (S1) failed to close with PTC enabled.	Warning	Refer to Section 5.
2397	S1 CB Not Open	Utility contact (S1) failed to open with PTC enabled.	Warning	Refer to Section 5.
240	LOW FUEL-DAY	Indicates day tank fuel supply is running low.	Warning	Check fuel supply and replenish as required.

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

Procedures

Adjusting Default Settings (Controller Configuration Menu) adjustment

Make sure Main Menu 1 is displayed and simultaneously press the Home Menu and Previous Main Menu buttons.
Press the buttons next to the and symbols to navigate between the three submenus.
Press the button next to the symbol until the + and − symbols are displayed.
Press the button next to the + or − symbol to select the desired option.
Press the symbol to save the changes.

Adjusting Values/Parameters (Adjust Menu) adjustment

⚠ If the Home button or Previous Main Menu button is pressed before pressing the save symbol, the changes are not saved.

⚠ Long periods of engine idling can eventually affect engine performance and may void engine warranty.

Press the button next to the symbol in the display until the + and − symbols are displayed.
If necessary, press the button next to the or symbols to move to the numeric character you wish to change.
Press the button next to the + symbol to increase the value; press the button next to the − symbol to decrease the value.
After adjusting, press the symbol to save; make sure the cursor is on the last numeric character before pressing.

Adjusting Values/Parameters (PowerCommand 2100 Control) adjustment

Press the button next to the down arrow symbol until the + and - symbols are displayed.
Press the button next to the arrow symbols to move to the numeric character to be changed.
Press the button next to + to increase the value or select a parameter; press - to decrease.
Press the save symbol to save the changes (make sure the cursor is on the last numeric character).
If the Home button or Previous Main Menu button is pressed before the save symbol, the changes are not saved.

Controller Configuration (PowerCommand 2100 Control) adjustment

Make sure Main Menu 1 is displayed.
Simultaneously press the Home Menu and Previous Main Menu buttons to view the first Controller Configuration menu.
Press the buttons next to the up and down symbols to navigate between menus.
Press the button next to the + or - symbol to select the desired option.
Press the save symbol to save changes; pressing Home or Previous Main Menu before the save symbol leaves changes unsaved.

Day Tank Controller Conversion 240 VAC to 120 VAC adjustment

Remove the two jumpers between terminals TB1-6 and TB1-7 and connect one between TB1-5 and TB1-6 and the other between TB1-7 and TB1-8.
Move selector switch S103 on the control PCB to the up position for 120V.
On the control transformer, remove the two jumpers between terminals H2 and H3 and connect one between H1 and H3 and the other between H2 and H4.

Torque Tester / Current Transformer Installation Check adjustment

Verify the dot on the CT faces toward the generator.
Verify CT21 is on U load leads, CT22 on V load leads, CT23 on W load leads.
Verify the correct CT secondary terminal (pin 2 high voltage / pin 3 low voltage) is used.
Check CT/PT wiring if a 335 Reverse Power shutdown occurs.

Generator/Base Board Isolation Procedure diagnostic

⚠ This test involves unregulated excitation; disconnect all loads.

⚠ HAZARDOUS VOLTAGE.

Tools: Voltmeter, 12 volt battery, Jumpers

Throw line circuit breaker OFF and shut down the set.
Remove control housing side cover; disconnect exciter stator X and XX leads from AC harness.
Prepare to measure output voltage across generator terminals while set runs.
Connect a 12V battery jumper positive (+) to X lead (Field +).
Check polarity again; polarity must be correct.
Start the set and connect battery negative (-) jumper to XX lead.
If rated output voltage or higher and all phases balanced, generator is likely OK.
If unbalanced troubleshoot main stator; if uniformly low troubleshoot exciter and field circuits.

Servicing the PMG - Testing diagnostic

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

Tools: Wheatstone bridge or digital ohmmeter

Disconnect leads P2, P3 and P4 from the voltage regulator.
Start the engine at the set and let the speed stabilize.
Measure voltage across lead pairs P2-P3, P3-P4 and P4-P2 (at least 150 VAC for 50 Hz, at least 180 VAC for 60 Hz).
If voltages are low or uneven, check all leads and connections before disassembling the PMG.
Stop the set and measure electrical resistance across P2-P3, P3-P4 and P4-P2 (approximately 4.4 ohms each winding).

Testing the Float Switch Assembly diagnostic

Tools: Ohmmeter, Feeler gauge

Remove fuel pump control cover, disconnect wiring jack, unscrew assembly from top of day tank.
Holding assembly vertical, test continuity between each pair of colored leads; all readings zero.
Lift each float to 1/8 inch (3 mm) below the C-clip stop and test continuity; all readings infinity.
Use pipe thread sealant when replacing the assembly.

Testing the Generator Stator and Rotor Windings diagnostic

⚠ Disconnect the starting battery cables (negative [-] first) to make sure the engine will not start while performing these tests.

Tools: Wheatstone bridge or digital ohmmeter (0.001 ohm precision), Megger or insulation resistance meter

Disconnect battery cables (negative first) so the engine will not start.
Measure winding resistance with a Wheatstone bridge or digital ohmmeter and compare to Table 6-1.
Measure winding insulation resistance between leads and laminations; replace if less than 1 megohm.
For the main stator, measure across each pair of stator leads (U1-U2, U5-U6, V1-V2, V5-V6, W1-W2, W5-W6).

Testing the PMG diagnostic

⚠ HAZARDOUS VOLTAGE.

Tools: Voltmeter, Wheatstone bridge or digital ohmmeter

Disconnect PMG leads PMG 2, 3 and 4 from AC harness connectors.
Start engine and let speed stabilize.
Measure voltage across PMG 2&3, PMG 3&4 and PMG 4&2.
Voltage should be at least 150 VAC (50 Hz) or 180 VAC (60 Hz) and equal.
Stop set and measure resistance across each pair; each winding approximately 4.4 ohms.

Testing the Rotating Rectifier Assembly 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.
Measure electrical resistance between each diode pigtail and the plate on which the diode is mounted.
Reverse the meter test probes and repeat the tests.
Replace the diode if resistance is high or low in both directions.

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
		CT1 - U load leads (A phase); CT2 - V load leads (B phase); CT3 - W load leads (C phase)	6 lead gensets: generator output leads routed through CTs; 12 lead gensets: load wires routed through CTs	12-lead sets have dual secondary CTs (3 pins); 6-lead sets have single secondary CTs (2 pins)
110V - 120V L-N	Single phase, 2-wire	Jumper locations for single phase, 2-wire		PTC Module AC wiring (0300-5382-01, -02)
190, 200, 208, 220, 230, 240, 380, 416, 440, 460, 600 (L-L)	3 (three phase)	3 or 4 wires		Voltage Configuration submenu; default = 3Ph 208V 4W
190V - 240V L-L	Three phase	Jumper locations for three phase, 190V-240V L-L		Use 0300-5382-01 for 190V-240V L-L, 50/60 Hz
200, 220, 230, 240 (L-L)	1 (single phase)	3 wires		Voltage Configuration submenu (Governor/Regulator Setup)
200V - 240V L-L	Single phase, 3-wire	Jumper locations for single phase, 3-wire		PTC Module AC wiring
380V - 600V L-L	Three phase	Jumper locations for three phase, 380V-600V L-L		Use 0300-5382-02 for 380V-600V L-L, 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 6BTA5.9 family

Part #	Description	Category
3824469	fuel pump gear puller	fuel_pump
3822509	injector puller	injector
3823276	injector bore brush	injector
3377259	bosch timing tool (ve)	other_service
3666496		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 6BTA5.9?

The Cummins/Onan 6BTA5.9 engine has an oil capacity of 16.0 liters.

What is the displacement of the Cummins/Onan 6BTA5.9?

The Cummins/Onan 6BTA5.9 has a displacement of 5.9 liters with 6 cylinders.

Which generators use the Cummins/Onan 6BTA5.9 engine?

The Cummins/Onan 6BTA5.9 powers 1 generator set(s), including Cummins/Onan DGDK.

What is a common problem with the Cummins/Onan 6BTA5.9 engine?

A commonly reported issue on generators using the Cummins/Onan 6BTA5.9 is: Over Current.