Home›Engines›Cummins/Onan HDKAS

Cummins/Onan HDKAS Engine

The Cummins/Onan HDKAS is a 0.9 L 3-cylinder liquid-cooled engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, including the HDKA. It holds 4.5 L (1.2 gal) of oil and 4.73 L (1.2 gal) of coolant.

Also known as: Cummins HDKAS

0.898 L

Displacement

Cylinders

1800 rpm

Rated speed

4.5 L

Oil capacity

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

Engine specifications

Oil capacity	4.5 L
Coolant capacity	4.73 L
Displacement	0.898 L
Cylinders	3
Aspiration	Liquid-cooled
Rated speed	1800 rpm

Generator sets powered by this engine

Cummins/Onan HDKA

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

Troubleshooting

Fault codes

Code	Meaning
1	Shutdown due to high engine coolant temperature
2	Shutdown due to a loss of engine oil pressure
3	Service fault — press Stop once to cause the two-digit, second-level shutdown code to blink
4	Cranking time exceeded 35 seconds

Symptoms & remedies

Symptom	Cause	Remedy
Engine does not crank	Battery dead	Check battery per Checkout [A] and recharge or replace; Check battery charger operation per Checkout [C]
Engine does not crank	CB11 circuit breaker open or B+ wiring to starter solenoid faulty	Check CB11 circuit breaker; if okay, jumper battery cable B+ connection to B1 starter solenoid terminal; check B+ wiring between K11 and B1 solenoid terminal and replace if bad; check K1 plunger travel for freedom to bottom in solenoid (necessary to open pull coil circuit)
Engine does not crank	No battery voltage between K11 terminal S and ground with S11 in Start position	Check B+ wiring to S11, and between S11 and K11; check NC contacts of A11-K15 and replace if bad
Engine does not crank	K11 does not energize	Test per Checkout [D] and replace if bad
Engine does not crank	No battery voltage at B1 solenoid terminal with S11 in Start position	Check battery cables for clean tight connections (ref. Checkout [B]); check B1 starter solenoid and motor: if bad, repair or replace
Engine cranks but does not start	Engine not getting fuel (exhaust smoke should be blue-white and fuel flow steady from fuel return line)	Check fuel system: fuel tank level, shut-off valves, fuel lines and connections, fuel filters, fuel pump and injection pump
Engine cranks but does not start	Incorrect fuel	See Operator's Manual recommendations
Engine cranks but does not start	Battery B+ not applied to glow plug heaters when switch S11 is in Preheat and Start positions	Check switch S11 per Checkout [G]; check heater relay per Checkout [E]; check heater wiring
Engine cranks but does not start	K14 fuel solenoid does not energize when S11 is in Start position	Check B+ circuit through S11; test S11 per Checkout [G]; test K14 per Checkout [F]
Engine starts but stops after running several seconds	Fault condition indicated by fault breaker CB12 on control panel	Check for a possible fault condition; if none, check fault monitors S1 through S4 and fault breaker CB12 for improper wiring
Engine starts but stops after running several seconds	Relay K12 not good	Check relay K12 per Checkout [H] and replace if bad
Engine starts but stops after running several seconds	DC control breaker trips after generator set is started	Check all B+ wiring for shorts to ground
Engine starts but stops after running several seconds	S6 power latch switch not closing or K1 solenoid rod not adjusted to correct length to allow the hold-in coil of K1 to latch	Check for closing of S6 power latch switch; if switch is OK, check mechanical adjustment of K1 solenoid: is rod adjusted to correct length to allow the hold-in coil of K1 to latch; if K1 adjustment is OK and problem remains, replace engine monitor PC board; check fuel solenoid adjustment
No AC output voltage at rated engine RPM	Load circuit breakers open	Locate cause of overload and correct as required; reset breaker, or replace if bad
No AC output voltage at rated engine RPM	Circuit open between brush block and voltage regulator	Check continuity of circuit breakers and replace if necessary; check for continuity and correct if circuit is open
No AC output voltage at rated engine RPM	Brushes stuck in holder or not making good contact with slip rings	Release brushes if jammed in holder; clean slip rings if dirty
No AC output voltage at rated engine RPM	Opens or grounds in rotor or stator	Test continuity of rotor, stator per Tests [B], [C]; replace component if defective
No AC output voltage at rated engine RPM	Incorrect field voltage	Test field voltage per TEST [A]; perform TEST [D]
No AC output voltage at rated engine RPM	F1 and F2 leads installed on incorrect terminals	Connect brush leads to correct terminals
Unstable voltage, engine speed stable	Broken wires or loose connections on voltage regulator assembly	Repair wiring or replace as required
Unstable voltage, engine speed stable	Wiring harness from regulator assembly to end bell faulty	Check wiring harness from regulator assembly to end bell per TEST [F]; repair as required
Unstable voltage, engine speed stable	Brushes not OK	Inspect brushes per procedure in Manual Section 4; repair or replace as required
Unstable voltage, engine speed stable	Voltage regulator faulty	Replace the voltage regulator per procedure [E]
Output voltage too high or too low	Engine not running at correct RPM	Set RPM per instructions in appropriate engine manual
Output voltage too high or too low	Voltage Adjust control on the regulator board not adjusted correctly	Set control per Voltage Adjustment [G]
Output voltage too high or too low	Voltage regulator connections not secure	Check that voltage regulator connections are secure
Output voltage too high or too low	Generator set output leads not properly connected	See TEST [H]
Output voltage too high or too low	Bad voltage regulator indicated by correctly functioning rotor/stator	Perform procedure [D]; if correctly functioning rotor/stator indicates a bad voltage regulator, replace it per procedure [E]
Output voltage too high or too low	Set AC output overloaded	Remove part of the set load
Unbalanced generator set output voltage	Load at generator set terminals causing unbalance	Remove load at generator set terminals
Unbalanced generator set output voltage	Generator set leads not connected and grounded properly	Check for correct grounding of generator set and load; correct as necessary
Unbalanced generator set output voltage	Generator set stator winding not continuous	Replace stator assembly
Unbalanced generator set output voltage	Load ground faults	Check load for ground faults and correct as necessary

Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.

Common problems

Engine does not crank
Cause: Faulty remote circuit
Fix: Try starting at the genset control panel. If the genset starts, have the remote circuit repaired as necessary.
Engine cranks but does not start
Cause: Engine not getting fuel
Fix: Open any closed shutoff valve; Check fuel level and refill as necessary; Prime the fuel system (p.11); Check for fuel (air) leaks at all fittings and tighten as necessary; Replace the fuel filter (p. 16).
No AC output voltage at rated engine RPM
Cause: Load circuit breakers open
Fix: Locate cause of overload and correct as required; reset breaker, or replace if bad
Output voltage too high or too low
Cause: Engine not running at correct RPM
Fix: Set RPM per instructions in appropriate engine manual
Engine starts but stops after running several seconds
Cause: Fault condition indicated by fault breaker CB12 on control panel
Fix: Check for a possible fault condition; if none, check fault monitors S1 through S4 and fault breaker CB12 for improper wiring
Unstable voltage, engine speed stable
Cause: Broken wires or loose connections on voltage regulator assembly
Fix: Repair wiring or replace as required
Unbalanced generator set output voltage
Cause: Load at generator set terminals causing unbalance
Fix: Remove load at generator set terminals
Unbalanced generator output voltage
Cause: Output still unbalanced with load removed at generator terminals
Fix: Check load for ground faults and correct as necessary
Status Indicator Light Dead F1
Cause: Battery condition; Battery connections; F1 fuse; Connections at the genset; Ground connections
Shutdown due to high engine coolant temperature 1
Shutdown due to a loss of engine oil pressure 2
Service Check Code 3
PROCESSOR FAULT—CODE NO. 43 43
Cause: Microprocessor RAM error during self-test
Fix: See an authorized Onan dealer
PROCESSOR FAULT—CODE NO. 42 42
Cause: Microprocessor ROM error during self-test
Fix: See an authorized Onan dealer
OVERCURRENT FAULT—CODE NO. 38 38
Cause: Too many loads connected
Fix: Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. Start up with no load and let the genset run for five minutes to cool down the inverter

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

Service intervals

Item	Action	Hours	Months	Notes
Air cleaner dust cap	Check	50 hr		Clean if required; footnote 3: perform more often in extremely dusty conditions
Air cleaner dust cap	Clean	8 hr		Clean if required; perform more often in extremely dusty conditions (table footnote 3)
Coolant level	Check	8 hr		Keep recovery tank level between COLD and HOT
Engine oil	Check	8 hr		Daily or after 8 hours
Engine oil level	Check	8 hr	0 mo	Keep oil level between FULL and ADD
Fuel level	Check	8 hr		Every Day/8 Hrs
Generator set	Inspect	8 hr		Footnote 1: check for oil, fuel, cooling and exhaust system leaks; check exhaust audibly and visually with set running
Genset	Inspect	8 hr		Every Day/8 Hrs; check for oil, fuel, coolant and exhaust system leaks
Oil level	Check	8 hr		Every Day/8 Hrs
Battery charging system	Check	100 hr		Weekly or after 50 hours
Battery specific gravity	Check	100 hr		Weekly or after 50 hours
Drive belt tension	Check	100 hr		Visually check belts for evidence of slippage (table footnote 4)
Engine oil	Change	50 hr		First service — Break-in: change engine oil after the first 20-50 hours of operation (RV QG/RV QG RM); perform at least once a year
Genset service (first service interval, all models)	Other	50 hr		First service — First service interval is 50 hours for all models.
Air Cleaner Dust Boot	Clean	100 hr	1 mo	Perform more often in dusty conditions (footnote 5)
Air cleaner element	Clean	100 hr
Antifreeze	Check	250 hr	6 mo	Monthly or after 100 hours
Battery	Check	100 hr	1 mo	See battery manufacturer's recommendations (footnote 2)
Fuel filter water/sediment	Drain	250 hr		Monthly or after 100 hours
V-belt tension	Check	250 hr	6 mo	Every Month/100 Hrs; check for slippage
Water in fuel	Drain	250 hr	6 mo	Every Month/100 Hrs; drain about one cup to remove water and sediment
Air Filter Element	Replace	150 hr		Every 150 hours, more often in dusty conditions
Engine Oil and Filter	Change	1000 hr		First service — Perform more often in dusty conditions; more often in hot weather; at least once a year
Genset service	Other	250 hr		First service — GEN TYPE QD 7.5/8 (Quiet Diesel 7.5/8 kW; model HDKAx)
Genset service — GEN TYPE GAS RV (Camp Power)	Other	150 hr		EC-30 service hour meter interval
Genset service — GEN TYPE GAS/LP (Marquis, Microlite, Micro Quiet)	Other	150 hr		EC-30 service hour meter interval
Genset service — GEN TYPE QD 5.5 (Quiet Diesel; model HDKBx)	Other	150 hr		EC-30 service hour meter interval
Genset service — GEN TYPE QD 6/8 (Quiet Diesel; model HDKAx)	Other	150 hr		EC-30 service hour meter interval
Anti-freeze	Check	250 hr
Crankcase oil and filter	Change	250 hr	6 mo	First service — Perform after first 35 hours of operation on new genset; change crankcase oil every 50 operating hours in extremely dusty conditions
Fuel filter element	Change	500 hr	12 mo	6 months or after 250 hours
Fuel shut-off linkage	Check	500 hr	12 mo	6 months or after 250 hours
Fuel tank sediment	Drain	250 hr	6 mo	Footnote 5: drain one cup of fuel to remove water and sediment
Generator assembly	Clean	250 hr	6 mo	Clean the generator set at least every six months
Generator set brushes	Check	250 hr	6 mo	Brushes inspected for wear and cleaning every six months
Genset service — GEN TYPE QD 10/12 (Quiet Diesel; models HDCAx, HDKCx)	Other	250 hr		EC-30 service hour meter interval
Water/sediment from fuel filter	Drain	250 hr	6 mo
Air Cleaner Element	Change	500 hr	12 mo	Perform more often in dusty conditions (footnote 5)
Coolant Anti-freeze Protection	Check	1000 hr	1 mo	Perform at least once a year
Coolant Anti-freeze Protection	Test	500 hr		Check Coolant Anti-freeze Protection

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	Bore	2.64 inch (67 mm)	inch (mm)
Clearance	Clearance to top of genset compartment	1	inch (25.4 mm)	minimum, including acoustic insulation
Clearance	Compartment opening free area, generator end	200	square inches	minimum
Clearance	Exhaust system distance from combustible material	3	in
Clearance	Fan belt deflection	0.4 (10 mm)	inch	22 pounds (10 kg) finger pressure at middle of belt
Clearance	Genset to bulkhead/other equipment (pusher/suction fan)	6	inches (152 mm)	minimum
Clearance	Minimum clearance between genset and compartment insulation	1	in
Clearance	Minimum clearance exhaust system to combustible material	3	in
Clearance	Minimum space between engine exhaust components and compartment insulation	3	in
Clearance	Muffler/tailpipe to combustible material	3	inches (76 mm)	minimum, unless insulated or shielded
Clearance	Stroke	2.68 inch (68 mm)	inch (mm)
Clearance	V-belt deflection	0.4	inch	with 20 pounds (10 kg) applied to middle of pulley span (10 mm)
Clearance	V-belt deflection at 20 pounds (10 kg) applied to middle of pulley span	0.4 inch (10 mm)	inch	at 20 lbs (10 kg)
Current	Battery charging DC alternator output	30	amp
Current	Starter motor draw at 12 VDC	100	A
Gap	Fan belt deflection	0.4	inch (10 mm)	22 pounds (10 kg) finger pressure at middle of belt
Gap	Fan belt deflection at middle of belt	0.4	inch (10 mm)	finger pressure of 22 pounds (10 kg)
Other	AUTO GEN disabled if safety input not verified	30	days
Other	Actuator speed control lever stop screw (beginning Spec B)	Turn in until just makes contact, then one more full turn (rotor not in place); set locknut		Adjust whenever a different actuator base assembly is installed
Other	Altitude power derate	approximately 3 percent per 1000-foot (305 m) increase in elevation	percent
Other	Battery cable size, total cable length 0 to 10 feet (0 to 3 m)	2	AWG	temperatures down to –20°F (–29°C)
Other	Battery cable size, total cable length 11 to 15 feet (3 to 4.5 m)	0	AWG	temperatures down to –20°F (–29°C)
Other	Battery cable size, total cable length 16 to 20 feet (4.5 to 6 m)	000	AWG	temperatures down to –20°F (–29°C)
Other	Battery compartment ventilation opening	1.7	in2	minimum at top and bottom
Other	Battery compartment ventilation opening	11	cm2	minimum at top and bottom
Other	Battery electrolyte specific gravity (fully charged)	1.260		at approximately 80°F (27°C)
Other	Battery electrolyte specific gravity, charge if below	1.215	specific gravity
Other	Battery electrolyte specific gravity, fully charged	1.260	specific gravity	at 80 F (27 C)
Other	Battery rating	425	CCA
Other	Battery rating	625	CCA	below 32°F (0°C)
Other	Battery recharge threshold (charge if specific gravity less than)	1.215	specific gravity
Other	Battery specific gravity charge threshold	1.215		charge battery if specific gravity is less than this
Other	Battery specific gravity, fully charged	1.260		at 80°F (27°C)
Other	Bore	2.64	inch (67 mm)
Other	Bore	2.99 (76) for HDKAL/HDKAQ; 2.83 (72) for HDKAR/HDKAS	in (mm)
Other	Bore	72	mm
Other	Bore	76	mm
Other	Brush wear limit (wire inserted into brush holder)	1	inch (25 mm)	replace brush and spring if wire enters holder this far or more
Other	Circuit breaker rating	35	A	2 pole, 60 Hz
Other	Clamping screw (beginning Spec B high-idle adjustment)	Run back in by hand until snug, back it out 1-1/2 turns, set lock nut	turns	After setting high-idle speed
Other	Compartment depth	25	in
Other	Compartment height	25	in
Other	Compartment width	38.4	in
Other	Compression Ratio	23 : 1
Other	Compression ratio	23 to 1
Other	Compression ratio	23:1
Other	Continuous operation at up to 80 percent of maximum power	6000	watts	80% of maximum power
Other	Cooling air requirement - Generator Inlet	100	in2
Other	Cooling air requirement - Radiator	200	in2
Other	Cooling system capacity	4.2 quart (4 l)	quart (l)	includes coolant recovery tank
Other	Cooling system capacity	4.73	L
Other	Cranking time that triggers fault	35	seconds	cranking time exceeded fault (4 blinks)
Other	Cranking time that trips fault code 4	35	seconds
Other	Cyclic horizontal forces	±500	lbs	±1 g-force
Other	Cyclic vertical forces	±1500	lbs	±3 g-force
Other	DC alternator output	30	amp	12 Volt Battery Charging
Other	Dimensions L x W x D	80.98 x 130.12 x 30.48	mm (3.188 x 5.125 x 1.20 inches)
Other	Displacement	1001	cm3
Other	Displacement	44	inch3 (719 cc)
Other	Displacement	44 inch3 (719 cc)	inch3 (cc)

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	50/50 ethylene glycol antifreeze and water			4.2 quarts (4 liters)	Provides protection to -34°F (-37°C). Use distilled water if available. Replace every 2 years.
Coolant	50/50 ethylene glycol based antifreeze and water				Mix thoroughly before adding; use clean soft tap water, distilled water or pure rain; select high quality antifreeze with corrosion inhibitors
Coolant	50/50 mixture ethylene glycol anti-freeze and water	Contains rust and corrosion inhibitor; no stop-leak additive	above -37°C	4.0 l	4.2 quart (4 l) capacity; suitable down to -34 F (-37 C)
Coolant	50/50 mixture of ethylene glycol anti-freeze and water	Reliable brand with rust and corrosion inhibitor; must not contain stop-leak additive	above -37°C		50/50 provides freeze protection to -34 F (-37 C); use distilled or soft water
Coolant	50/50 mixture of ethylene glycol anti-freeze and water as shipped; use ethylene or propylene glycol anti-freeze solution containing rust and corrosion inhibitor	Anti-freeze must not contain a stop-leak additive; water must be clean, low in minerals and free of corrosive chemicals; use distilled water if available	above -37°C	4.0 l	Factory fill suitable down to -34 deg F (-37 deg C); cooling system capacity 4.2 quart (4 l) includes coolant recovery tank; replace coolant every two years
Coolant	50/50 mixture of ethylene glycol anti-freeze and water; ethylene or propylene glycol solution containing rust and corrosion inhibitor	No stop-leak additive; use clean, low-mineral water, distilled if available	above -37°C	4.0 l	Suitable for temperatures down to -34° F (-37° C); cooling system capacity 4.2 quart (4 l) including coolant recovery tank; replace coolant every two years
Coolant	50/50 mixture of ethylene glycol antifreeze and water		above -37°C	4.0 l	Suitable for temperatures down to –37 °C (–34 °F); antifreeze should be fully formulated with rust inhibitors and coolant stabilizers, mixed with fresh (distilled) water
Coolant	50/50 mixture of water and ethylene glycol		above -37°C		Best quality ethylene or propylene glycol antifreeze fully formulated with rust inhibitors and coolant stabilizers, but not stop-leak additives. Use fresh water low in minerals; distilled water is best. Shipped 50/50 mixture good for -34 F (-37 C).
Coolant	50/50 mixture of water and ethylene glycol (or propylene glycol) antifreeze	Fully formulated with rust inhibitors and coolant stabilizers but not with stop-leak additives; use fresh water low in minerals, distilled best	above -37°C	4.73 L	Shipped with recommended 50/50 mixture, good for -34 F (-37 C); cooling system capacity 1.25 gal (4.73 L)
Coolant	Ethylene or propylene glycol anti-freeze, 50/50 mixture		above -34°C	4.2 quart	Must contain rust and corrosion inhibitor; no stop-leak additives
Coolant	50/50 mixture of water and ethylene glycol (best quality ethylene or propylene glycol antifreeze, fully formulated with rust inhibitors and coolant stabilizers, no stop-leak additives)		above 37°C	4.73 L	Good for -34°F (-37°C); Cooling System Capacity 1.25 gal (4.73 L); use distilled water; replenish recovery tank between COLD and HOT
Coolant	Ethylene glycol antifreeze, fully formulated with rust inhibitors and coolant stabilizers		above 37°C	4.0 l (4.2 qt) incl. recovery tank	50/50 mixture recommended for all climates
Engine oil	CH-4, CG-4, or CF-4	API performance class		3.0 quarts (2.6 liters)	May be combined with SJ, SH, or SG. Select viscosity grade per Chart 1 based on ambient temperature.
Engine oil	SAE 10W-30 / 10W-40 / 0W-30 / 5W-30				Use viscosity chart to select grade for expected ambient temperature range; avoid mixing grades or brands
Engine oil	SAE 15W-40	API CF, CF-4, CG-4, CH-4, CI-4 or CJ-4 (diesel)			OnaMax 15W-40 #326-5336; multi-grade recommended year-round in liquid-cooled engines; synthetic oil not recommended
Engine oil	SAE 15W-40 multi-grade recommended for year-round use	API Class CF-4 or CF or better		4.7 L	Pre-start checks state engine oil capacity 4.7 liters (5 quarts); Specifications state lubricating oil capacity with oil filter 6.0 liters (6.34 quarts). Choose viscosity grade per ambient temperature before next oil change.
Engine oil	SAE 15W-40 multi-grade recommended for year-round use (choose viscosity grade per ambient temperature chart, Figure 2)	API Class CG-4, CF-4, CF or better		4.1 L	Lube oil capacity 4.34 qt (4.1 L) including filter
Engine oil	SAE 15W-40 multi-grade recommended for year-round use; choose viscosity grade for ambient temperature range before next oil change	API Class CF-4 or CF or better		5.1 L	Lube Oil Capacity 5.39 qt (5.1 L); see Figure 2 SAE viscosity grade vs ambient temperature
Engine oil	SAE viscosity grade chosen from Chart 1 (Oil Viscosity vs. Temperature) for ambient temperatures expected until next oil change	API performance Class CH-4, CG-4 or CF-4, may be in combination with SJ, SH or SG (e.g. CH-4/SJ)		2.6 l	3 quart (2.6 l) with filter
Engine oil	SAE viscosity grade per Chart 1 (Oil Viscosity vs. Temperature)	API CH-4, CG-4 or CF-4 (may combine with SJ, SH or SG)		2.6 l	3 quarts (2.6 l) capacity with filter
Engine oil	SAE viscosity grade per Chart 4-1 (oil viscosity vs. temperature)	API performance Class CH-4, CG-4 or CF-4D, may be combined with SJ, SH or SG (e.g. CH-4/SJ)		2.6 l	Oil capacity with filter 3 quart (2.6 l)
Engine oil	SAE viscosity grade per engine lubrication section	API classification per engine lubrication section			Refer to Engine Workshop Manual for oil recommendation
Engine oil	SAE viscosity grade selected per anticipated ambient temperature (Chart 1, Oil Viscosity vs. Temperature)	API performance Class CH-4, CG-4 or CF-4, may be in combination with performance Class SJ, SH or SG (e.g. CH-4/SJ)		3.0 quart (2.6 l)	Oil capacity with filter; change oil if not appropriate for ambient temperatures during break-in
Engine oil	SAE viscosity per anticipated ambient temperature (Table 1, Oil Viscosity vs. Temperature)	API classification CC and later		4.26 liters (4.5 quarts)	Do not use synthetic oil or non-detergent oil. Do not mix different brands of oil. (Specifications section lists lube oil capacity 4.5 qt (4.25 L) including filter.)
Engine oil	SAE-30	API SJ, SL or SM (gasoline)			OnaMax SAE-30 #326-5339; preferred summer grade for optimum oil consumption control in air-cooled engines
Engine oil	Performance Class CH-4, CG-4 or CF-4		-40°C to 40°C	3.0 quart	Select SAE grade based on ambient temperature; see oil viscosity chart
Engine oil	API Class CH-4, CG-4, or CF-4	SAE viscosity grade based on ambient temperature	above -34°C	2.6 l	See Chart 1 for viscosity selection by temperature
Engine oil	5W-30	API CF, CF-4, CG-4, CH-4, or CI-4	-28°C to 10°C
Engine oil	10W-30 10W-40	API CF, CF-4, CG-4, CH-4, or CI-4	-18°C to 27°C
Engine oil	15W-40 (OnaMax)	API CF, CF-4, CG-4, CH-4, or CI-4	-12°C to 38°C		Multigrade oils such as SAE 15W-40 are recommended for year round use

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
1	Engine Over Temperature	Engine coolant temperature exceeded 115°C (239°F) for 10 seconds	Shutdown	Check coolant level and add if needed; check for blockages/dirt on radiation fins; reduce load
1, 2, 3, 4	First level faults	First-level faults; avoid interpreting as second-level codes 11, 22, 33, or 44	Shutdown	Pay close attention to the pause sequence
2	Low Oil Pressure	Low oil pressure cutoff switch did not open	Shutdown	Check engine oil level, add or drain as needed
3	Service Check	Second-level service fault; flash STOP/PRIME once for 2-digit code	Warning	See second-level fault code
4	Over Crank	Cranking exceeded 30 seconds without engine starting	Shutdown	Check fuel level and prime; check air filter; replace oil with proper viscosity; check fuel fittings; replace fuel filter
4 blinks	Cranking time exceeded 35 seconds	Status indicator light repeatedly blinks four times	Shutdown	Check fuel supply and priming before re-cranking
8	Cranking Fault	Starter or cranking circuit malfunction	Shutdown	Contact authorized Onan dealer
11	Overload Fault	Genset is overloaded	Shutdown	Reduce electrical load
12	Over Voltage	Control unable to maintain rated voltage	Shutdown	Contact local dealer or distributor
13	Under Voltage	Control unable to maintain rated voltage	Shutdown	Reduce load (air conditioners, battery chargers)
14	Over Frequency	Engine governor unable to maintain rated frequency	Shutdown	Contact local dealer or distributor
15	Under Frequency	Engine governor unable to maintain rated frequency	Shutdown	Reduce load
17	Fuel Pump Fault	Controller sensed open circuit; bypassable fault prior to Spec F, discontinued beginning Spec F	Shutdown	Try priming by holding control switch at Stop; reconnect fuel pump leads; test pump on 12 V battery; check P1-2/E2-1 and E2-2/ground continuity.
18	Glow Plug Circuit Protection Fault	Controller sensed short circuit; bypassable fault prior to Spec F, discontinued beginning Spec F	Shutdown	Reconnect HR-1 to glow plug bus bar; check HR-1 and A1-J8 for continuity to ground; replace engine harness or controller assembly.
19	Governor Actuator	Control sensed an open or shorted circuit	Shutdown	Contact local dealer or distributor
21	Starter Solenoid Circuit Protection Fault	Controller sensed short circuit; discontinued beginning Spec F	Shutdown	Reconnect K-1 to starter solenoid; test solenoid and starter; reconnect A1-J6; check continuity to ground; replace controller assembly.
22	Governor Actuator Overload	Duration of operation near full-duty cycle beyond design limit	Shutdown	Reduce load; check air filter; check exhaust system for blockage
23	High Engine Temperature Fault	Engine temperature exceeds limit	Shutdown	Check coolant level and allow engine to cool
24	Throttle Control Fault	Engine throttle control malfunction	Shutdown	Contact authorized Onan dealer
25	Engine Sensor Fault	Engine sensor malfunction or reading error	Shutdown	Contact authorized Onan dealer
26	ENGINE BELOW SPEED TARGET	Governor unable to regulate to target speed	Shutdown	Reduce connected load; prime fuel system
27	Voltage Sense	Control unable to sense output voltage	Shutdown	Contact local dealer or distributor
28	DC SENSE LOST	Controller unable to sense DC bus voltage	Shutdown	Open circuit breaker; disconnect excessive loads before starting
29	High Battery Voltage	Voltage across battery system greater than 19 Volts	Shutdown	Check battery bank connections (parallel 12V not series 24V); select lower boost charge rate
31	Overspeed Fault	Engine speed exceeds 3600 rpm	Shutdown	Contact authorized Onan dealer
32	Low Cranking Speed	Cranking speed less than 180 RPM for more than 2 seconds	Shutdown	Clean/tighten battery connections, recharge/replace battery; replace engine oil with proper viscosity
33	HIGH ENGINE COOLANT TEMPERATURE	Engine coolant temperature exceeded design limit	Shutdown	Check coolant level and leaks; remove blockages; reduce load; clean cooling system
34	HIGH INVERTER TEMPERATURE	Inverter heat sink temperature exceeded design limit	Shutdown	Remove blockages from air openings; reduce connected appliances
35	Control Card Failure	Microprocessor EEPROM error during self test	Shutdown	Contact local dealer or distributor
36	Engine Stopped	Engine stopped without receiving command from control	Shutdown	Check fuel level and prime; check air filter; check for mechanical damage
37	INVALID GENSET CONFIGURATION	Genset configuration preprogrammed at factory	Shutdown	See an authorized Onan dealer
38	Over Current (Field Overload)	Low power factor loads	Shutdown	Reduce load; check appliances for proper operation
39	Low Battery Voltage Fault	Battery voltage dropped below 9 volts while genset running; discontinued beginning Spec F	Warning	Clean and tighten battery cable connections; avoid running genset while cranking the vehicle engine where genset batteries supplement vehicle batteries.
41	Generator Rotor	Control unable to sense field or output voltage	Shutdown	Contact local dealer or distributor
42	Processor	Microprocessor ROM error during self test	Shutdown	Contact local dealer or distributor
43	Processor	Microprocessor RAM error during self test	Shutdown	Contact local dealer or distributor
44	Not assigned	Second-level code 44 has not been assigned a fault
45	Speed Sense	Control unable to sense quadrature frequency	Shutdown	Contact local dealer or distributor
46	INVERTER POWER SUPPLY FAULT	Low battery voltage or power supply device failure	Shutdown	Avoid running genset during vehicle engine cranking; clean battery connections; recharge battery
48	Generator Field Sense	Control unable to sense field voltage	Shutdown	Contact local dealer or distributor
57	Over Prime	Priming exceeded 3 minutes	Shutdown	Check control switch; remove any object holding switch in STOP/PRIME position
restore	Restoring fault code blinking	Fault code stops blinking after five minutes	Info	Press Stop three times within three seconds to restore fault code blinking

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 V-Belt Tension adjustment

⚠ Accidental starting can cause severe personal injury or death. Disconnect the negative (−) cable(s) at the battery(ies) before working on the genset.

Disconnect the negative (−) cable(s) at the battery(ies) to prevent the engine from starting and remove the top belt guard.
Loosen the alternator pivot bolt first and then the adjusting bracket bolt on top.
Tighten belt tension by pivoting the alternator outwards; hold tension by tightening the adjusting bracket bolt.
Apply 20 pounds (10 kg) to the middle of the pulley span and measure belt deflection, which should be 0.4 inch (10 mm).
Tighten the alternator bolts when tension is correct.
Secure the belt guard and reconnect the battery cables (negative [−] last).

Fan Belt Adjustment adjustment

⚠ Do not operate the generator set without the belt guard in place.

⚠ Stop the set and disable by disconnecting battery cables before service.

Remove the generator set starting battery cables, negative cable first.
Remove the belt guard from the front of the set.
Loosen the bolt through the long slot in the alternator mounting bracket.
Slide the alternator until the tension is correct.
Check tension: 22 pounds finger pressure deflects belt 0.4 inch.

Governor Actuator Speed Control Lever Stop Adjustment (Spec B and later) adjustment

Loosen the stop screw locknut and back the screw out a few turns.
Turn the stop screw in until it just makes contact.
Turn the screw 1 full turn further in and set the locknut (rotor not in place procedure).
Alternatively with actuator in place: loosen set screw locknut, turn stop screw in until just makes contact, set locknut.

High-Idle Speed Adjustment adjustment

⚠ Do not let engine speed exceed 3600 RPM.

Tools: tachometer

Remove front housing panel.
Set up tachometer.
Remove actuator cover and reattach leads.
Start generator set and push actuator rotor clockwise fully (about 12 mm).
Adjust high-idle speed to 3500-3600 RPM.
For Spec A, adjust screw; for Spec B, adjust screws and set locknut.
Let rotor go; generator should stop and display fault code.
Restart and recheck high idle speed.

Setting GEN TYPE adjustment

⚠ GEN TYPE sets the service interval for service messages and critical automatic starting parameters.

Navigate to the SETUP & INFO display and press ENTER.
Navigate to the SETUP GENSET display and press ENTER; the GEN TYPE is displayed.
Press SET; the display will flash.
Use the UP/DOWN key to select the GEN TYPE and press ENTER when the appropriate type is displayed.

Setting Quiet Time (QT) Start & End adjustment

⚠ QUIET ON mode prohibits the genset from automatically starting between the start and end of Quiet Time.

Use the UP/DOWN key to navigate to the QT START or QT END display; the current setting is shown.
Press SET to change the setting.
Use the UP/DOWN key to change the value.
Press ENTER to store the new time.

Setting Safety Type adjustment

⚠ If it has not been setup (SafeType NONE), automatic operation will not be allowed.

Use the UP/DOWN key to select the correct type of safety input: Ignition, Brake, or Park.
Press ENTER to store in permanent memory.

Setting the Hour-Meter (SET Gen Hour) adjustment

⚠ ENTER to unlock prevents unauthorized changes to the hour-meter.

Check the hour-meter on the genset and record the reading.
Enter the SETUP & INFO menu and navigate to the SETUP GENSET display; press ENTER.
Use the DOWN key to select the SET Gen hour's display; press SET.
Press ENTER at the ENTER to unlock display to continue.
Hold down the UP/DOWN key and scroll until the left-most digit matches the desired value.
Release the UP/DOWN key and wait four seconds for the underline to move to the next digit; scroll to its desired value.
Set each successive digit to the right until the correct genset hours are displayed, then press ENTER to store.

Valves − Adjust, All adjustment

Remove and install cover and panels, valve cover
Adjust valve lash
Test run unit

Voltage Adjustment adjustment

⚠ Touching uninsulated live parts can cause severe injury or death.

Tools: voltmeter

Start generator set; allow voltage and frequency to stabilize 3-5 seconds.
Rapidly press Start switch 6 times within first minute to enter voltage adjust mode.
To increase: press and quickly release Start switch; each press increases about 0.6 volts.
To decrease: press and hold Start switch about 1 second; each press decreases about 0.6 volts.
Repeat until desired voltage.
Wait 20 seconds for amber light to stop blinking.
Press Stop switch to save adjustment.

Voltage Adjustment Procedure adjustment

⚠ Do not change the 50/60 Hz setting on the regulator.

⚠ The V/Hz Break Point pot is factory set and sealed; do not adjust.

Tools: flat-blade screwdriver, voltmeter

Attach a voltmeter securely to the L1 and L2 leads.
Start the generator set and place a typical load on its output.
Use a flat-blade screwdriver to set the voltage adjust potentiometer for correct voltage.
Retighten the locking nut when complete.

Voltage Adjustment [G] adjustment

⚠ Disconnect both battery cables, negative (-) cable first, when repairs are made.

⚠ Contact with high voltage can cause severe personal injury or death.

Tools: Voltmeter, Flat-blade screwdriver

Attach a voltmeter securely to the L1 and L2 leads.
Start the generator set and place a typical load on its output.
Use a flat-blade screwdriver to set the voltage adjust potentiometer for correct voltage.
For most 60 Hz applications, the ideal setting is 120 VAC at 60-61 hz.
Retighten the locking nut when complete.

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
		AC Present + positive	#14	Positive input for shore AC present sensing; do not connect 120VAC or 240VAC line voltage.
		AC Present - ground	#13	Supplied by UL Listed 120VAC to 12-16VAC transformer, or the 12VDC ground side of a UL Listed 120VAC to 12VDC plug-in power supply.
		Battery Ground (Negative)	Wire #1	Supplies ground/negative side of the circuit for the EC-20; must be supplied from the genset.
		Battery ground (negative)	#1	Supplies the ground or negative side of the circuit for the EC-30; must be supplied from the genset.
		Genset Status Light	Wire #6	Diagnostic output from the genset that flashes the red light in the START/STOP switch; decoded by the EC-20 to display a text fault message.
		Genset status light	#6	Diagnostic output that flashes the red light in the START/STOP switch to indicate a genset fault; decoded to a text fault message.
		Not Used	Wire #4
		Start/Preheat	Wire #3	Supplies start/preheat signal to the genset; controlled by the STOP/START switch and in automatic mode by the EC-20.
		Start/preheat	#3	Supplies the start/preheat signal to the genset; controlled by the STOP/START switch and, in automatic mode, by the EC-30.
		Stop Output	Wire #2	Active low or grounded output supplying the stop signal to the genset; controlled by the STOP/START switch.
		Stop output	#2	Active low or grounded output to the genset; controlled by the STOP/START switch and, in automatic mode, by the EC-30.
		Switched B+ From Genset	Wire #5	Switched to battery positive when the genset is running; provides genset hour-meter and running signal.
		Switched B+ from genset	#5	Switched to battery positive voltage when the genset is running; provides genset hour meter and running indication.
	single	Quadrature power connection Q60 - 60 Hz, Q50 - 50 Hz units	Q1, Q50, Q60	Note 2: Quadrature power connection Q60-60 Hz, Q50-50 Hz units. Note 3: AVR reference voltage. Note 1: From J2-15 for field flashing.
100	1	Reconnection chart
100	1	reconnection chart
100	single	reconnection chart	L0
100	single-phase			50 Hz; see reconnection chart
100	single-phase	L0, L1	T4, T3, L2, L1, Q50, Q60, T2, T1, S2, 2, S1, Q1
100/200	1	Reconnection chart		Wiring diagram 612-6637 reconnection chart
100/200	1	reconnection chart
100/200	single	As shown	T1, T2, T3, T4; L0(N), L1	100/200 volts only; stator resistance values differ (T1-T2, T3-T4: 0.150 ohm; Q1-Q60: 2.3 ohms)
100/200	single	reconnection chart	L0, L1
100/200	single-phase			50 Hz; see reconnection chart
100/200	single-phase	L0(N), L1	Q50, Q60, T2, T1, S2, 2, S1, Q1	50 Hz
110	1	reconnection chart	T4, T3; L1
110	single-phase	L0, L1	T4, T2, T3, T1, L0
110/190	3	50 HZ CODE Z	T1-T12
110/220	1	As shown	T1, T2, T3, T4	See reconnection chart for other voltages
110/220	1	reconnection chart	T4, T3, T2, T1; L2, L1, L0(N)

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

Common questions

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

The Cummins/Onan HDKAS engine has an oil capacity of 4.5 liters.

What is the displacement of the Cummins/Onan HDKAS?

The Cummins/Onan HDKAS has a displacement of 0.898 liters with 3 cylinders.

Which generators use the Cummins/Onan HDKAS engine?

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

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

A commonly reported issue on generators using the Cummins/Onan HDKAS is: Engine does not crank. Cause: Faulty remote circuit. Fix: Try starting at the genset control panel. If the genset starts, have the remote circuit repaired as necessary..

Cummins/Onan HDKAS Engine

Engine specifications

Generator sets powered by this engine

Troubleshooting

Fault codes

Symptoms & remedies

Common problems

Repair guides

Service intervals

Service specifications

Recommended fluids

Fault codes

Procedures

Voltage reconnection

Common questions