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Kohler CH740 (14 kW models); CH1000 (20 kW models) Engine

The Kohler CH740 (14 kW models); CH1000 (20 kW models) is a 2-cylinder engine rated at 3600 rpm. It powers generator sets from Kohler, including the 14RCA, 20RCA and RCA.

Also known as: Kohler CH740 (14 kW models); CH1000 (20 kW models)

Cylinders

3600 rpm

Rated speed

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

Engine specifications

Cylinders	2
Rated speed	3600 rpm

Generator sets powered by this engine

Kohler 14RCA Kohler 20RCAKohler RCA

How to read your Kohler engine serial & model number →

Common problems

The generator shuts down due to a main power overload. Main Power Overload Shutdown
Fix: Check the circuit breaker and ensure it is not tripped. If necessary, replace the circuit breaker.
Paralleling issues occur, such as incorrect synchronization or failure to maintain parallel operation. Faults Related to Paralleling
Fix: Verify that all paralleling settings are correct in the controller parameters. Check the paralleling cables and connections for any faults.
Low battery voltage warnings are displayed on the controller display. Battery Low Warnings
Fix: Check the battery connections and ensure they are secure. Replace the battery if it is low on charge.
This generator has absorbed more than 25% reactive power (magnetic excitation current) for 20 seconds. LossOfField
Cause: Generator voltage on this generator is not calibrated correctly. Generator voltage on other generator is not calibrated correctly. Bus voltage on this generator is not calibrated correctly. Bus voltage on the other generator is not calibrated correctly.
This generator does not know if the metering is connected or the orientation of the connection. This means that the generators can’t share load accurately until this information is known. MeterUnknown
Cause: System commissioning and startup not yet complete. See the APM instructions.
The two generators that are intended to be paralleled have incompatible model numbers. CfgModelNum
Cause: Incorrect configuration of one of the generators. Different generator types. The paralleled generator sets must be the same kW model. (i.e. two 14 kW or two 20 kWor 26 kW models).
The system voltage of the two generators intended to be paralleled is not the same. CfgSysVolt
Cause: One of the two generators is incorrectly configured. Intermittent connections on RBUS network wiring.
The primary controller has lost communication with the secondary controller. (A secondary controller was detected, then communication was lost.) LossOfComm2
Cause: RBUS disconnected, secondary controller battery disconnected, updating firmware in secondary controller, or intermittent RBUS connections.
The power metering on this controller gives a signal that is not consistent with the system configuration. Reversing the power direction does not resolve the problem. ErraticSig
Cause: Bad wiring to the CT. Too much tension on wires from the CT to the controller.
The generator set cranks but does not start, starts hard, lacks power, or operates erratically.
Cause: Air cleaner clogged
Fix: Clean and/or replace the air cleaner.
The generator has verified that the metering is connected correctly and that the direction is consistent with expected power direction. MeteringOk
Cause: Status message indicates that the CT is connected to the generator correctly.
The generator has been attempting to synchronize for over 2 minutes without success. SyncFailure
Cause: Generator is hunting. Advanced speed control settings need adjustment. Load is changing frequently to disturb the online generator.
The generator has applied load (using the other generator) and has observed no current on the power sensing inputs. NoCurrent
Cause: The CT is not connected to the controller. The output leads from the generator do not go through the CT in the correct direction. See the APM instructions.
The controller displays fault messages TP-7092
The bus is measured to be live when no generators are connected to it (both contactors open). BusLiveDead
Cause: Bus metering V9A and V9B connections to V9 of paralleling protection harness are connected incorrectly.

Compiled from service & troubleshooting documentation across every generator set that uses the Kohler CH740 (14 kW models); CH1000 (20 kW models).

Maintenance schedule

Item	Spec	Part #	Interval
Air filter	Replace air cleaner element at intervals specified in the service schedule. Replace more often under extremely dusty or dirty conditions.	—	100 hr
Fuel filter	Change fuel flexible lines and connections quarterly. Check main tank supply level weekly. Change fuel piping yearly.	—	52 hr
Oil filter	Replace oil filter yearly or 200 hours.	—	200 hr
Battery	Check the electrolyte level of batteries with filler caps monthly. Remove filler caps and verify that electrolyte level reaches bottom of filler holes. Refill as necessary with distilled water.	—	30 hr
Belt	Check control and power wiring connections yearly. Check remote control system monthly if equipped. Check visible wear or damage quarterly.	—	12 hr
Coolant	Check air ducts, louvers yearly. Check exhaust system leakage weekly. Check insulation, fire hazards yearly.	—	52 hr
Oil	Change oil every 8 hours of engine operation or yearly. Replace filter yearly or 200 hours.	—	100 hr
Spark plug		—

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Oil level	Check	8 hr		Every 8 hours of engine operation
Oil level (14 kW)	Check	8 hr		Every 8 hours of engine operation
Oil level (20 kW)	Check	8 hr		Every 8 hours of operation
Oil level, 14 kW models	Check	8 hr		Every 8 hours of engine operation
Oil level, 18/20 kW models	Check	8 hr		Every 8 hours of engine operation
Oil level, 20 kW models	Check	8 hr
Oil level (26 kW)	Check	24 hr		Every 24 hours of operation
Oil level, 26 kW models	Check	24 hr
Change oil	Change	100 hr		Yearly or 100 hours
Change oil (14 kW models)	Change	100 hr	12 mo	Yearly or 100 hours
Change oil (14 kW)	Change	100 hr	12 mo	Yearly or 100 hours
Oil cooler	Clean	100 hr		20 kW models; Yearly or 100 hours
Oil cooler (20/26 kW)	Clean	100 hr	12 mo	Yearly or 100 hours; inspect and clean
Replace filter (20/26 kW)	Replace	100 hr	12 mo	Yearly or 100 hours
Air cleaner service	Clean	300 hr	12 mo	Yearly or hours shown
Change oil (20 kW models)	Change	150 hr	12 mo	Yearly or 150 hours
Oil change (20/26 kW)	Change	150 hr	12 mo	Yearly or 150 hours
Oil cooler (20RCA/RCAL only)	Clean	150 hr	12 mo	Yearly or 150 hours; inspect and clean, must be kept free of debris
Replace oil filter (20 kW models)	Replace	150 hr	12 mo	Yearly or 150 hours
Replace filter (oil)	Replace	200 hr		14 kW: Yearly or 200 hours; 20 kW: Yearly or 100 hours
Replace oil filter (14 kW models)	Replace	200 hr	12 mo	Yearly or 200 hours
Replace oil filter (14 kW)	Replace	200 hr	12 mo	Yearly or 200 hours
Air cleaner service	Replace	300 hr	12 mo	Yearly or hours shown; service more frequently under dusty/dirty conditions
Brushes and collector ring	Inspect	300 hr	12 mo	Yearly or 300 hours; authorized distributor/dealer only
Optional 300 hour extended life oil change kit (26 kW)	Change	300 hr	24 mo	2 years or 300 hours
Spark plugs	Replace	300 hr		14 kW: 300; 20 kW: 150 and 300 hours
Spark plugs (14 kW)	Replace	300 hr		Hours shown
Spark plugs (20/26 kW)	Replace	300 hr		150/300 hours shown
Crankcase breather hose	Check	500 hr		Yearly or 500 hours
Crankcase breather hose	Inspect	500 hr	12 mo	Yearly or 500 hours
Crankcase breather hose	Replace	500 hr	12 mo	Yearly or 500 hours
Replace stepper motor coupling and bushing	Replace	500 hr		Authorized distributor/dealer only
Wire-cable insulation condition	Inspect	500 hr	36 mo	3 years or 500 hours
Wire-cable insulation condition	Test	500 hr	36 mo	3 years or 500 hours
AC electrical system visible wear or damage	Inspect		3 mo	Quarterly
Air ducts, louvers	Clean		12 mo	Yearly; visually inspect and clean
Battery and rack corrosion	Clean		12 mo	Yearly
Battery charger operation, charge rate	Check		1 mo	Monthly
Battery electrolyte level and specific gravity	Check		12 mo	Yearly; not necessary for maintenance-free batteries
Battery terminals and boots	Clean		12 mo	Yearly

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
Gap	Spark plug gap	0.76	mm (0.030 in.)
Other	Battery wrap length	1067 (42)	mm (in.)
Other	Battery wrap length	864 (34)	mm (in.)
Other	Engine cooldown time delay	5	minutes
Other	Engine start crank cycle	3 attempts, 15 sec crank / 15 sec off
Other	Governed frequency high shutdown	110	% of frequency setpoint for >10 sec	10 sec inhibit after engine start
Other	Governed frequency low shutdown	90	% of frequency setpoint for >10 sec, or 1 Hz below setpoint for >60 sec	10 sec inhibit after engine start
Other	Heater wrap rating	50	Watts
Other	Heater wrap rating	65	Watts
Other	Plug cord length	75 (3)	mm (in.)
Other	Power cord length	1677 (66)	mm (in.)
Other	Power cord length	1830 (72)	mm (in.)
Other	Power cord length	483 (19)	mm (in.)
Other	Specific gravity, battery fully charged	1.260		electrolyte temperature 80 F (26.7 C)
Other	Specific gravity, battery needs charging (below)	1.215		electrolyte temperature 80 F (26.7 C)
Pressure	Engine oil pressure	172-241	kPa (25-35 psi)
Pressure	Fuel pressure required, LPG	1.7-2.7	kPa (7-11 in. H2O)
Pressure	Fuel pressure required, Natural Gas	0.9-2.7	kPa (3.5-11 in. H2O)
Pressure	LPG fuel supply	1.7-2.7	kPa
Pressure	Natural gas fuel supply	0.9-2.7	kPa
Resistance	Resistance through brushes	0.1-0.2	ohms	without meter lead resistance
Resistance	Resistance through the brushes	0.1-0.2	ohms	without meter lead resistance
Resistance	Rotor insulation (megohmmeter)	500	kOhms minimum	500 VDC applied
Resistance	Rotor resistance, cold (14 kW)	5.2	ohms	cold
Resistance	Rotor resistance, cold (14RCA/L 2F5/2G5)	5.2	ohms	cold
Resistance	Rotor resistance, cold (20 kW)	5.6	ohms	cold
Resistance	Rotor resistance, cold (20RCA/L 2F7/2G7)	5.6	ohms	cold
Resistance	Rotor resistance, cold (26 kW)	6.4	ohms	cold
Resistance	Stator insulation (megohmmeter)	500	kOhms minimum	500 VDC applied
Resistance	Stepper motor coil resistance (per half coil)	38.5	ohms
Resistance	Stepper motor coil resistance per half coil	38.5	ohms
Resistance	Temperature sensor (OTS) resistance at 100 C (212 F)	180-200	ohms	100 C (212 F)
Resistance	Temperature sensor (OTS) resistance at 100C (212F)	180-200	ohms	100 C (212 F)
Resistance	Temperature sensor (OTS) resistance at 30 C (86 F)	2100-2400	ohms	30 C (86 F)
Resistance	Temperature sensor (OTS) resistance at 30C (86F)	2100-2400	ohms	30 C (86 F)
Speed	Crank disconnect speed	750	RPM (12.5 Hz)
Speed	Engine crank disconnect speed	750	RPM
Speed	Engine overspeed shutdown	115	% of normal running speed for >0.3 sec
Speed	Engine run speed (60 Hz)	3600	RPM
Speed	Engine run speed 60 Hz / 50 Hz	3600 / 3000	RPM
Speed	Engine speed high shutdown	115	% of normal running speed for >0.3 sec
Speed	Engine speed low shutdown	85	% of normal running speed for >3 sec
Speed	Engine underspeed shutdown	85	% of normal running speed for >3 sec
Speed	Overspeed shutdown test	115	% of rated speed (69 Hz @60 Hz, 58 Hz @50 Hz)
Temperature	Carburetor heater thermostat OFF	16 ± 3	C (60 ± 5F)
Temperature	Carburetor heater thermostat ON	4 ± 4	C (40 ± 7F)
Temperature	Controller operating temperature	-30 to 70	C
Temperature	Controller storage temperature	-40 to 85	C
Temperature	High lube oil temperature shutdown	325	F (163 C)
Temperature	High lube oil temperature warning	300	F (149 C)
Temperature	Thermostat off temperature	27	C (80 F)
Temperature	Thermostat on temperature	16	C (60 F)
Torque	Alternator adapter bolts	69	Nm (51 ft. lb.)
Torque	Alternator adapter bolts (14/20 kW)	69	Nm (51 ft. lb.)
Torque	Alternator adapter bolts (26 kW)	69	Nm (51 ft. lb.)
Torque	Alternator mounting bolts	14.9	Nm (11 ft. lb.)
Torque	Alternator mounting bolts (14/20 kW)	14.9	Nm (11 ft. lb.)
Torque	Alternator mounting bolts (26 kW)	14.9	Nm (11 ft. lb.)
Torque	Alternator thrubolt	85	Nm (63 ft. lb.)
Torque	Alternator thrubolt (14/20 kW)	85	Nm (63 ft. lb.)

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
Engine oil		Service class SJ or higher	1.8 L (1.9 qt.)	Oil capacity 14 kW
Engine oil	10W-30 synthetic	Service class SJ or higher		Add 5W-30 or 10W-30 synthetic oil when oil level is low
Engine oil	10W-50 extended-life synthetic		1.9 L (qt.)	Premium oil option, 26 kW models, requires fewer oil changes
Engine oil	5W-30 or 10W-30	API Service Class SG, SH, or SJ synthetic oil	1.8 L	14 kW models; capacity 1.8 L (1.9 qt.)
Engine oil	5W-30 or 10W-30 API Service Class SG, SH, or SJ synthetic	API SG/SH/SJ	1.8 L (qt.)	14 kW models
Engine oil	5W-30 synthetic	Service class SJ or higher		Refer to Oil Matrix chart for oil recommendation based on air temperature
Engine oil	KOHLER PRO 10W-50	Service class SJ or higher		All season Kohler PRO 10W-50 is ideal; extends oil/filter change to 300 hours (2 years) with KOHLER PRO extended life oil filter
Engine oil	Synthetic, API Service Class SG or higher	API SG or higher		Check oil level at or near, not over, full mark on dipstick before operation
Fuel	LP gas or natural gas			Minimum fuel supply pressure NG: 1.2-2.7 kPa (5-11 in. H2O); LP: 1.7-2.7 kPa (7-11 in. H2O)

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
AC Sens Loss	AC Sensing Loss	ATS sensing lost. In Auto mode, generator output AC sensing is lost. Detection begins 10 seconds after start.	Warning	Contact an authorized distributor/dealer for service
AC Sens Loss Shutdown	Loss of AC sensing shutdown	Less than 5% of rated voltage measured on Phase A for 3 seconds in AUTO	Shutdown	Check loose wiring and connections; check all AC leads; troubleshoot alternator
AC Sens Loss Shutdwn	Loss of AC sensing shutdown	Controller shut down the generator because there was less than 5% of rated voltage measured on Phase A for 3 seconds, only in AUTO.	Shutdown	Check for loose wiring and connections. Check all AC leads. Troubleshoot alternator.
AC Sens Loss Warning	Loss of AC sensing warning	Less than 5% of rated voltage on Phase A for 1 second, 10 seconds after crank disconnect	Warning	Check loose wiring and connections; check all AC leads; troubleshoot alternator
ATS ComError	ATS Communication Error	ATS communication error; interface connection lost	Warning	Check communication wiring between transfer switch interface board and generator set.
ATS ComError Warning	ATS communication error	Controller lost communication with the RXT ATS	Warning	Check connection to ATS module
ATS PhaseRot	ATS PhaseRot	ATS phase rotation mismatch; ATS will not transfer	Warning	Correct the ATS connection. Refer to the ATS Installation manual, wiring diagrams, and labels on the transfer switch.
Accy PwrOver Warning	Accy PwrOver Warning	An over current fault (short circuit) on the accessory controller power output.	Warning	Contact an authorized distributor/dealer for service
AccyPwrOver Warning	Accessory Power Overload	Overcurrent fault (short circuit) on the accessory controller power output	Warning	Check wiring to RBUS accessories; troubleshoot RBUS accessories
Advanced Diagnostic	Advanced Diagnostic	Shutdown during the reduced speed portion of an exercise. Event history shows Advanced Diagnostic Active. Engine restarts, runs at full speed for 2 minutes, and stops. Controller returns to AUTO mode.	Shutdown	If the generator set does not restart and return to AUTO, check for other faults that prevent generator set operation.
Aux Input	Auxiliary Input	Optional customer-connected input (from PIM) is closed	Shutdown	Check customer-supplied equipment.
Aux Input Shutdwn	Auxiliary input shutdown	Digital input for a custom shutdown (AuxiliaryInputShutdown - PIM) was activated (low).	Shutdown	Check customer equipment connected to the PIM module.
Batt Chg Flt	Battery Charger Fault	Input to PIM from an external battery charger (not the built-in battery charger).	Warning	Check external battery charger.
Battery CRLow Warning	Battery cranking low warning	Battery voltage dropped to 11 VDC or less for 30 seconds or more.	Warning	Check engine starting battery; check battery charger DC output from RDC2
Battery CrLo Warning	Low Cranking Battery Voltage Warning	Engine starting battery voltage falls below 11 VDC for more than 10 seconds. Inhibited during crank cycle. Clears when battery voltage returns to acceptable level.	Warning	Check the battery rating and condition. Check the battery charger operation. Charge or replace the battery.
Battery High	Battery High	Engine starting battery voltage rises above 16 VDC for more than 10 seconds (inhibited during crank)	Warning	Check battery rating/condition and charger operation
Battery High Warning	Battery high warning	Battery voltage above the high warning setting for 10 seconds or more.	Warning	Check engine starting battery.
Battery Low Warning	Battery low warning	Controller measured battery voltage below low warning setting for 90 seconds or more	Warning	Check engine starting battery; check battery charger DC output from RDC2
Battery Voltage High	Battery Voltage High	Engine starting battery voltage rises above 16 VDC for more than 10 seconds. Inhibited during crank cycle. Clears when voltage returns to acceptable level.	Warning	Check the battery rating and condition. Check the battery charger operation.
Battery Voltage Low	Battery Voltage Low	Engine starting battery voltage falls below 12.5 VDC for more than 90 seconds when engine not running. Not operative during crank cycle. Clears when voltage returns to acceptable level.	Warning	Check the battery rating and condition. Check the battery charger operation. Charge or replace the battery.
Chk DateTime Warning	Check Date and Time Warning	DC power to controller interrupted and date/time may not be correct	Warning	Verify time and date settings
Default Pars Warning	Default Parameters Warning	Controller has been loaded with default parameters	Warning	Configure settings as required for desired operation
Emerg Stop Shutdwn	Emergency stop shutdown	Optional emergency stop button pressed or emergency stop leads ESS and/or ESN not connected	Shutdown	Reset the emergency stop button and clear the fault; check ESS and ESN connections; if no E-stop, connect ESS and ESN together.
Eng Speed High	Eng Speed High	Engine speed exceeds 115% of normal running speed for more than 0.3 seconds	Shutdown	Contact an authorized distributor/dealer for service
Eng Speed Low	Eng Speed Low	Engine speed drops below 85% of normal running speed for more than 3 seconds	Shutdown	Reduce the load; on 20RCA/RCAL check enclosure thermostat; contact dealer if it persists
Engine M/N Invalid Shutdwn	Engine model number invalid shutdown	Generator model number has not been entered.	Shutdown	Enter the generator set model number from the RDC2 keypad, or use SiteTech to select the genset model number.
Engine Speed High	Engine Speed High	Engine speed exceeds 115% of the normal running speed for more than 0.3 seconds.	Shutdown	Contact an authorized dealer for service.
Engine Speed High Shutdwn	Engine speed high shutdown	Engine speed, calculated from AC frequency, was above the high speed setting for 0.3 seconds or more.	Shutdown	Troubleshoot engine operation per the engine service manual.
Engine Speed Low	Engine Speed Low	Engine speed drops below 85% of the normal running speed for more than 3 seconds.	Shutdown	Reduce the load. Check enclosure thermostat and reset if tripped. Contact an authorized dealer for service.
Engine Speed Low Shutdwn	Engine speed low shutdown	Engine speed below the low speed setting for 3 seconds or more after crank disconnect; enclosure thermostat may have tripped.	Shutdown	Troubleshoot engine; check enclosure thermostat and reset if tripped
Exer Not Sch	Exercise Not Scheduled	No exercise is scheduled on the controller.	Warning	Set the exerciser per Section 3.6
Frequency High	Frequency High	Governed frequency exceeds 110% of the system's frequency setpoint for more than 10 seconds. Active 10 seconds after engine start.	Shutdown	Contact an authorized distributor/dealer for service
Frequency High Shutdwn	Frequency high shutdown	Frequency on Phase A exceeded high frequency setting for 10 seconds	Shutdown	Troubleshoot engine operation per the engine service manual.
Frequency Low	Frequency Low	Governed frequency falls below 90% of the system frequency setting for more than 10 seconds, or 1 Hz below setting for more than 60 seconds. Active 10 seconds after engine start.	Shutdown	Reduce the load and restart; on 20RCA/RCAL check enclosure thermostat; contact dealer if it persists
Frequency Low Shutdwn	Frequency low shutdown	Frequency on Phase A was less than the low limit for 10 seconds, or 10 Hz or more less than rated for 60 seconds or more.	Shutdown	Troubleshoot engine; check and reset enclosure thermostat
Fuel Leak Shutdwn	Fuel Leak Shutdown	Digital input for Fuel Tank Leak Shutdown (PIM) activated (low)	Shutdown	Check customer equipment connected to the PIM module
Fuel Level Low Shutdwn	Fuel Level Low Shutdown	Digital input for Low Fuel Level Shutdown (PIM) activated (low)	Shutdown	Check customer equipment connected to the PIM module
GenBrkerOpen Warning	Generator Circuit Breaker Open	Voltage at generator set but none measured on emergency side of ATS (RXT required)	Warning	Check line circuit breaker; correct short circuits or overloading before resetting
Ground Fault Warning	Ground Fault Warning	Digital input for Ground Fault Warning (PIM) active (low)	Warning	Check customer equipment connected to the PIM module
High Lube Oil Temperature Shutdown	High lube oil temperature shutdown	Oil temperature higher than 325 F (163 C).	Shutdown	See Overheats troubleshooting; check cooling
High Lube Oil Temperature Warning	High lube oil temperature warning	Oil temperature higher than 300 F (149 C).	Warning	See Overheats troubleshooting
Lo Crank Vlt	Low Cranking Voltage	Battery voltage dropped below 3.5 VDC during engine cranking.	Warning	Charge or replace the battery.
Lo Crank Vlt Warning	Low cranking voltage warning	During cranking, battery voltage measured less than 60% (7.2V or 14.4V) for 6 seconds or more.	Warning	Check cranking battery.
Locked Rotor	Locked Rotor	No engine rotation sensed during cranking; shuts down 3 seconds after detection	Shutdown	Check the battery. Check for loose connections. Contact an authorized dealer for service.
Locked Rotor Shutdwn	Locked rotor shutdown	No rotation of the engine or alternator was detected for 3 seconds or more during cranking.	Shutdown	Check cranking circuit; troubleshoot engine and alternator; check aux winding circuit breaker
Low Oil Level or Oil Pressure	Low Oil Level or Oil Pressure	Oil level switch on the 26 kW indicates low oil level. LOP switch indicates low oil pressure for more than 5 seconds. Active 30 seconds after crank disconnect. Does not protect against low oil level.	Shutdown	Check for leaks in the lubrication system. Check the oil level and add oil if low. Check the oil level or oil pressure switch and wiring. If fault persists, do not run the generator set; contact an authorized dealer.
MainPwrOverL	MainPwrOverL	Main power overload; an over current fault on the controller output (short circuit).	Shutdown	Contact an authorized distributor/dealer for service
MainPwrOverL Shutdwn	Main power overload shutdown	Internal current limit circuit tripped, indicating an overcurrent condition on the DC power supply circuit.	Shutdown	Check crank, run, and flash relay circuits for short circuits.
Not In Auto Warning	Not in auto warning	The RDC2 controller is not in AUTO; generator will not start from an ATS or remote device.	Warning	Press the Auto button to ensure automatic system operation.
Not in Auto	Not in Auto	The generator set is not in Automatic (standby) mode. Remote start and stop commands from a transfer switch or remote switch will be ignored.	Warning	Press AUTO to place the generator set in Automatic mode, when appropriate.
Oil Press Low	Oil Pressure Low	The LOP switch indicates low oil pressure for more than 5 seconds. Function becomes active 30 seconds after crank disconnect (30 second inhibit). The low oil pressure shutdown does not protect against low oil level.	Shutdown	Check for leaks in the lubrication system. Check the oil level and add oil if the level is low. Check the oil pressure switch and wiring. If the fault persists, do not run the generator set. Contact an authorized dealer for service.
Oil Pressure Low Shutdwn	Oil Pressure Low Shutdown	The low oil pressure switch was closed for 5 seconds or more; inhibited until 30 seconds after crank disconnect.	Shutdown	Check for oil leaks; check oil level and add oil; check oil pressure sensor
Oil Pressure OpenCR Warning	Oil pressure open circuit warning	Oil pressure switch closure has not been detected after shutdown.	Warning	Check the oil pressure switch connection. Test the LOP switch.
Over Crank	Over Crank	Three unsuccessful starting attempts.	Shutdown	Check the fuel supply, spark plug, and battery. Check for loose connections. Contact an authorized dealer for service.
Over Crank Shutdwn	Overcrank shutdown	The engine did not start during the crank cycle (15 second time delay).	Shutdown	Check the alternator, fuel supply, cranking circuit, cranking battery; troubleshoot engine.
RBUS ComError Warning	RBUS communication error warning	The controller has lost communication with an RBUS device that had previously been communicating properly.	Warning	Check connection to the RBUS device.
Spd Sens Flt	Speed Sensor Fault	Engine speed sensor has failed or engine stalled.	Shutdown	Contact an authorized distributor/dealer for service
Spd Sens Flt Shutdwn	Speed sensor fault shutdown	The speed signal was lost; also occurs if the engine stalls.	Shutdown	Check leads 55, 66, F+, and F- between the alternator and the controller; check the engine.
Volts L1-L2 (AB) High Shutdwn	Volts L1-L2 High Shutdown	Voltage from Phase A to Phase B exceeded the high limit for longer than the 2 second delay setting.	Shutdown	Troubleshoot alternator.
Volts L1-L2 (AB) Low Shutdwn	Volts L1-L2 Low Shutdown	Voltage from Phase A to Phase B was greater than 5% of rated but less than the low voltage setting for longer than the 10 second delay; enclosure thermostat may have tripped.	Shutdown	Troubleshoot alternator; check and reset enclosure thermostat
Volts L1-L2 High	Volts L1-L2 High	Output voltage exceeds 120% of the system nominal voltage for more than 2 seconds.	Shutdown	Contact an authorized distributor/dealer for service
Volts L1-L2 Low	Volts L1-L2 Low	Output voltage falls below 80% of the nominal system voltage for more than 10 seconds.	Shutdown	Reduce the load and restart; on 20RCA/RCAL check enclosure thermostat; contact dealer if it persists

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

Procedures

RDC2 Voltage Calibration Using SiteTech adjustment

Tools: digital voltmeter, personal computer, SiteTech software

Connect PC to controller via USB
With generator off, connect multimeter across L1/L2 (AC volts)
Start generator set
Compare voltmeter reading to controller display
Calculate new Genset Calibration Factor Voltage using (Vmeter / Vcontrol) x Fold = Fnew
Enter new value into SiteTech and click Apply Changes
Verify voltmeter matches controller display
Repeat for L2-L3 and L3-L1 if three-phase
Press OFF to stop generator set

RDC2 Voltage Calibration Using the Controller Keypad adjustment

Tools: digital voltmeter

With generator off, connect digital multimeter across L1 and L2, set to AC volts
Start generator set with RUN button
Navigate to Generator Metering menu, press Select; Volts L1-L2 displayed
Press Select; voltage number flashes
Use up/down arrows to match voltmeter reading
Press Select to confirm
Step to Return screen
Press OFF to stop generator set

VSC Current (Load) Calibration Using the Controller Keypad adjustment

Tools: clamp-on DC current probe or DC current meter

Connect DC current probe/clamp meter to measure generator current
Start generator with RUN button
Adjust system voltage to obtain rated current output with battery bank attached (or use load bank)
Trip output breaker
Navigate to Generator Metering menu, select Generator Load
Press and hold Select for No-Load Calibration; verify breaker open, confirm Yes
Close output breaker; verify rated output current, confirm Yes
Verify displayed load is correct; recalibrate if necessary
Press OFF to stop generator set

Voltage Calibration Using RDC2 Keypad adjustment

Tools: Digital voltmeter

With set off, connect DVM to measure output voltage L1-L2 (AC volts).
Press RUN to start generator set.
Press Select, navigate to Generator Metering menu.
Press Select to display Volts L1-L2; compare with voltmeter.
If incorrect, press Select (flashes), adjust with arrows, press Select to save.
Wait 30-60 seconds for voltmeter reading to stabilize.
For three-phase, repeat for L2-L3 and L3-L1.
Press OFF to stop generator set.

Governor System Operation Test diagnostic

⚠ Hazardous voltage. Moving parts.

Tools: Ohmmeter

Verify carburetor throttle linkage is connected to stepper motor.
Check for broken or loose wiring or plug connections.
Check stepper motor operation at startup (open then closed position).
Open circuit breaker, disconnect starting battery, shut off fuel supply.
Disconnect stepper motor plug P6 to access terminals.
Check coil resistance across pins 2-3 and pins 1-4.
Inspect linkage and bushings; replace as necessary.
Disconnect linkage; verify free full range of motion.

Resetting the Controller After a Fault Shutdown diagnostic

⚠ Always identify and correct cause of fault before resetting

Press Select to go to Overview menu while fault message is displayed
Press Select again to show active fault message
Press Select; 'Confirm Clear Fault: NO' displayed
Press UP arrow; 'Confirm Clear Fault: YES' displayed
Press Select to clear fault
Press Select to return to overview menu; controller changes to OFF mode
Press AUTO to place generator set in automatic mode

Separate Excitation diagnostic

⚠ Hazardous voltage. Moving parts.

Tools: DC ammeter, 10-amp fuse, 12-volt automotive battery

Disconnect black FN and FP leads at brush holder terminals.
Connect DC ammeter, 10-amp fuse, and 12-volt battery to FP/FN brush leads.
Start engine; verify ammeter reading remains stable.
Check AC output across stator leads; compare to specifications.
If rotor and stator good, check wiring, fuses, controller settings.

Separate Excitation Procedure diagnostic

⚠ Hazardous voltage. Operate the generator set only when all guards and electrical enclosures are in place.

Tools: DC ammeter, 10-amp fuse, 12-volt automotive battery

Disconnect the black FN and FP leads from the alternator at the brush holder terminals.
Connect a DC ammeter, 10-amp fuse, and a 12-volt automotive battery to the FP and FN brush leads.
Note and record the ammeter reading.
Start the engine and check that the ammeter reading remains stable.
An increasing reading indicates a shorted rotor; a decreasing reading suggests a running open.
Check for AC output across the stator leads and compare to Section 1 specifications.
If rotor and stator are good, check the wiring, fuses, and controller settings and connections.

Test Low Oil Pressure (LOP) Switch diagnostic

Tools: Ohmmeter or continuity tester, Oil pressure gauge

Press OFF to stop engine.
Disconnect lead 13 from the switch.
Use ohmmeter/continuity tester to verify switch is closed (grounded).
Start engine and verify switch opens after a few seconds.
If not operating, remove LOP switch, install oil pressure gauge.
Start and run generator set.
Verify oil pressure within specified range before replacing LOP switch.

12-Lead Generator Reconnection Procedure installation

⚠ Hazardous voltage. Disconnect all power sources before opening the enclosure.

Tools: digital multimeter, voltmeter

Press the OFF button on the RDC2 controller.
Disconnect the engine starting battery, negative lead first.
Disconnect utility power to the generator set.
Remove the circuit breaker cover and the controller panel to access the alternator leads and CTs.
Replace the circuit breaker with the correct part for the new voltage rating.
Select the desired voltage connection and connect the leads per the diagram.
Reconnect the engine starting battery, negative lead last.
Check system voltage, frequency, and phase settings and change them if necessary.
Connect a digital multimeter (DVM) to the generator set output.
Press RUN to start the generator set.
Use a voltmeter to check for the correct voltage output; calibrate the RDC2 voltage if necessary.
Press OFF to stop the generator set.
Reconnect utility power to the generator set.
Press AUTO to place the generator set in automatic mode.

Access the Air Intake Area installation

Unlock and raise the enclosure roof.
Pull the air intake panel up and off its four bushings.
Remove the cover panel over the terminal block to make electrical connections.
After connections complete and battery installed, reinstall panels.

Battery Installation Procedure installation

⚠ Battery acid can cause severe injury or death

⚠ Explosion hazard from battery gases

Ensure starting battery is fully charged before placing in service.
Clean battery posts and/or adapters if necessary.
Install battery post adapters, if needed.
Place battery in the housing.
Connect positive (+) lead to engine starting battery.
Connect negative (-) lead to engine starting battery.

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-volt engine electrical system, single starter motor, negative ground	Battery negative to ground terminal on or near starter motor; battery positive to positive terminal on starter solenoid	All generator set models use a negative ground with a 12-volt engine electrical system
		Engine start connection for non-RXT transfer switch or remote start/stop switch	Terminals 3 and 4 on generator set terminal block	Route engine start leads through separate conduit from AC power and load leads
		RXT transfer switch to generator set terminal block A, B, PWR, COM	P10-1 through P10-4 (transfer switch) to A, B, PWR, COM (generator set)	Terminal block connections 3 and 4 not used with Model RXT ATS
	1	Single-phase leads 1-2, 3-4	1, 2, 3, 4	4-lead generator sets are not reconnectable
	3	Three-phase leads 1-4, 2-5, 3-6, 7-10, 8-11, 9-12	1-12	12-lead generator sets are reconnectable to voltages shown on the generator set specification sheet
	Single Phase	12-volt engine electrical system, single starter motor	Positive to starter solenoid; negative to ground on or near starter motor	Negative ground; follow polarity markings
	Single Phase	4-lead/12-lead reconnection per 12-Lead Generator Reconnection diagram (Figure 27)	Single-phase leads 1-2, 3-4; sensing leads 11-44	4-lead generators are not reconnectable; 12-lead three-phase reconnectable to voltages shown on spec sheet
	Three Phase	12-lead reconnection per Figure 27	Leads 1-4, 2-5, 3-6, 7-10, 8-11, 9-12; sensing leads V7, V8, V9	Also route leads through current transformers (CTs) and change controller voltage setting; replace line circuit breaker for new voltage
100/200	1	Single
100/200	3	Delta
110/220	1	Single
110/220	3	Delta
115/230	1	Single
12 VDC		Single starter motor, negative ground engine electrical system	Positive (+) to starter solenoid terminal; negative (-) to ground terminal on or near starter motor	Remove negative lead first when disconnecting, reconnect negative lead last
120	1	Single		Genset System Voltage/Frequency/Phase table for controller setup
120/208	3	Wye		Voltage configuration (Figure 4-12)
120/208, 120/240, 277/480	3	3-phase 2G7	12
120/240	1	Single		Voltage configuration (Figure 4-12)
120/240	1	Single phase 2F7	4
120/240	3	Delta		Voltage configuration (Figure 4-12)
127/220	3	Wye
220	1	Single
220/380	3	Wye
230	1	Single
230/400	3	Wye
240	1	Single
240/416	3	Wye
277/480	3	Wye		Voltage configuration (Figure 4-12)

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

Which generators use the Kohler CH740 (14 kW models); CH1000 (20 kW models) engine?

The Kohler CH740 (14 kW models); CH1000 (20 kW models) powers 3 generator set(s), including Kohler 14RCA, Kohler 20RCA, Kohler RCA.

How often should you change the oil in the Kohler CH740 (14 kW models); CH1000 (20 kW models)?

The Kohler CH740 (14 kW models); CH1000 (20 kW models) oil change interval is every 100 hours.

What is a common problem with the Kohler CH740 (14 kW models); CH1000 (20 kW models) engine?

A commonly reported issue on generators using the Kohler CH740 (14 kW models); CH1000 (20 kW models) is: The generator shuts down due to a main power overload.. Fix: Check the circuit breaker and ensure it is not tripped. If necessary, replace the circuit breaker..