HomeEnginesKohler CH740/CH1000

Kohler CH740/CH1000 Engine

The Kohler CH740/CH1000 is a 0.07 L 2-cylinder natural aspiration engine rated at 3600 rpm, producing up to 17.6 kW. It powers generator sets from Kohler, including the RDC2. It holds 1.9 L (0.5 gal) of oil.

Also known as: Kohler CH740/CH1000

Part of the Kohler CH740 engine family — 2 variants share parts & fitment.

0.0725 L
Displacement
2
Cylinders
3600 rpm
Rated speed
17 kW
Gross power

Engine specifications

Oil capacity1.9 L
Displacement0.0725 L
Cylinders2
Aspirationnatural aspiration
Rated speed3600 rpm
Gross power17 kW

Generator sets powered by this engine

1
Kohler RDC2

How to read your Kohler engine serial & model number →

Common problems

15
  • Under Voltage Paralleled Voltage L1-L2 Low Warning
    Fix: Press AUTO or OFF *
  • Under Frequency Paralleled Frequency Low Warning
    Fix: Press AUTO or OFF *
  • This generator has absorbed more than 25% reactive power (magnetic excitation current) for 20 seconds 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. LossOfField
  • 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 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 has verified that the metering is connected correctly and that the direction is consistent with expected power direction. Status message indicates that the CT is connected to the generator correctly. MeteringOk
  • 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 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.
  • The bus is measured to be dead when one of the generators is supposed to be supplying voltage to the bus (closed contactor) BusDeadLive
    Cause: Bus metering V9A and V9B connections to V9 of paralleling protection harness are connected incorrectly.
  • The Automatic Paralleling Module has stopped communicating on RBUS. (An APM was detected on the RBUS network but is no longer communicating.) LossOfComAPM
    Cause: APM is unplugged. Primary controller is powered down. Check the battery connections. See previous page for more information. Intermittent connections on RBUS network wiring. Check RBUS communication connections.
  • Reverse Power Paralleled Real Power Low Warning
    Fix: Press AUTO or OFF *

Compiled from service & troubleshooting documentation across every generator set that uses the Kohler CH740/CH1000.

Maintenance schedule

ItemSpecCapacityPart #Interval
Air filter
Fuel filter
Oil filter
Battery
Belt
Coolant
Oil
Spark plug

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

Procedures

10
RDC2 Voltage Calibration Using SiteTech adjustment

Tools: digital voltmeter, personal computer, SiteTech software

  1. Connect PC to controller via USB
  2. With generator off, connect multimeter across L1/L2 (AC volts)
  3. Start generator set
  4. Compare voltmeter reading to controller display
  5. Calculate new Genset Calibration Factor Voltage using (Vmeter / Vcontrol) x Fold = Fnew
  6. Enter new value into SiteTech and click Apply Changes
  7. Verify voltmeter matches controller display
  8. Repeat for L2-L3 and L3-L1 if three-phase
  9. Press OFF to stop generator set
RDC2 Voltage Calibration Using the Controller Keypad adjustment

Tools: digital voltmeter

  1. With generator off, connect digital multimeter across L1 and L2, set to AC volts
  2. Start generator set with RUN button
  3. Navigate to Generator Metering menu, press Select; Volts L1-L2 displayed
  4. Press Select; voltage number flashes
  5. Use up/down arrows to match voltmeter reading
  6. Press Select to confirm
  7. Step to Return screen
  8. 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

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

⚠ Do not load RDC2.4 firmware onto a red- or green-board controller

Tools: personal computer, USB cable, SiteTech software

  1. Download latest firmware file (.bin) from Kohler Power Resource Center or dealer portal
  2. Connect controller to PC via USB cable
  3. Start SiteTech; program recognizes connected device
  4. Click Update Firmware
  5. Browse to and select firmware file, click Open
  6. Verify current/new version and file name, click Update Firmware
  7. Wait for 'Firmware Updated Successfully' message, click Close
Setting the OnCue Password, RDC2 and VSC operation
  1. Press Select then down arrow to Networking Information menu
  2. Press Select for Networking Status
  3. Press Down arrow for Networking Configuration
  4. Press Select for Reset OnCue Password
  5. Press and hold Select until 'Reset OnCue Password? No' appears
  6. Press Up arrow to change No to Yes
  7. Press Select to reset; serial number and new password display for 10 seconds
Controller Replacement Procedure, Models 14RESA and 20RESA/B/C/D repair

⚠ Do not load settings from a green-board controller onto a red/blue-board controller or vice versa

Tools: voltmeter

  1. Review service kit information and confirm correct kits
  2. Open enclosure roof
  3. Press OFF button, disconnect utility power, verify with voltmeter
  4. Disconnect starting battery, negative lead first
  5. Remove two mounting screws, lift controller, disconnect harnesses
  6. Remove old controller
  7. If replacing original green-board controller with revised controller, install relay/breaker kit GM95104
  8. Reconnect harnesses, install new controller, reconnect battery negative last
  9. Reconnect utility power
  10. Set date/time/exerciser, update firmware, run Controller Setup and Voltage Calibration
  11. Replace covers/panels; reset OnCue password if used
Controller Replacement Procedure, Models 8/10/12RESV/L repair

⚠ Hazardous voltage can cause severe injury or death; disconnect all power sources before opening enclosure

⚠ Accidental starting can cause severe injury or death; disconnect battery cables, negative first

Tools: voltmeter, enclosure locking tool, screwdriver

  1. Open enclosure roof using locking tool
  2. Press OFF button on controller
  3. Disconnect utility power at building distribution panel; verify off with voltmeter
  4. Disconnect engine starting battery, negative lead first
  5. Remove two controller mounting screws and lift bottom edge of controller
  6. Note connections on back of controller, then disconnect all harnesses and leads
  7. Remove old controller
  8. Reconnect all harnesses to new controller assembly
  9. Install controller onto junction box with the two screws
  10. Reconnect battery, negative lead last
  11. Reconnect utility power by closing distribution panel breaker
  12. Set date/time and exerciser when prompted
  13. Check and update firmware to latest version via SiteTech or USB utility
  14. Perform Controller Setup (Section 5)
  15. Perform Voltage Calibration (Section 6)
Controller Replacement, Model RCL (RCL, RCLA, RCLB) repair

Tools: voltmeter

  1. Open/remove enclosure service door
  2. Press OFF, disconnect utility power
  3. Disconnect starting battery negative lead first
  4. Remove customer connection access panel, verify power off with voltmeter
  5. Remove two mounting screws, lift controller, disconnect P1/P2/P4/P5/P6
  6. Remove old controller, reconnect harnesses to new controller
  7. Install controller, replace access panel
  8. Reconnect battery and utility power
  9. Update firmware, set date/time/exerciser, run Controller Setup and Voltage Calibration
Controller Replacement, Models 14/20RCA/L repair

Tools: voltmeter

  1. Open enclosure roof, press OFF, disconnect utility power
  2. Disconnect starting battery negative lead first
  3. Remove two mounting screws, lift controller
  4. Verify utility power off at AC connections with voltmeter
  5. Disconnect harnesses, remove old controller
  6. Reconnect harnesses to new controller, install with screws
  7. Reconnect battery, reconnect utility power
  8. Set date/time/exerciser, update firmware, run Controller Setup and Voltage Calibration
VSC Controller Replacement, 6VSG repair

Tools: voltmeter

  1. Review service kit info, open enclosure roof
  2. Press OFF, disconnect utility power, verify with voltmeter
  3. Disconnect starting battery negative lead first
  4. Remove two mounting screws, lift controller, disconnect harnesses
  5. Remove old controller; if upgrading from green to revised board install relay kit GM92804
  6. Reconnect harnesses, install controller, reconnect battery negative last
  7. Reconnect utility power, update firmware
  8. Run Controller Setup and Voltage/Current Calibration
  9. Reset OnCue password if used

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

VoltagePhaseConnectionLeadsNotes
100/2001Single
100/2003Delta
110/2201Single
110/2203Delta
115/2301Single
1201SingleGenset System Voltage/Frequency/Phase table for controller setup
120/2083Wye
120/2401Single
120/2403Delta
127/2203Wye
2201Single
220/3803Wye
2301Single
230/4003Wye
2401Single
240/4163Wye
277/4803Wye

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 Kohler CH740 family

8
Part #DescriptionCategory
223316Fuse, 10 A, 250 Vother_service
292937Fuse, 20 A, 250 Vother_service
GM77569Original RDC2other_service
GM85969-1Controller, RDC2 - Distributor (original, discontinued, use GM92089)other_service
GM90304Revised RDC2 Controllerother_service
GM92088-1Controller, RDC2 - Distributor (revised)other_service
GM95149Diode Harness (for green-board controllers built before 9/15/14)other_service
GM95500Battery charging diode harness field kitother_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 Kohler CH740/CH1000?

The Kohler CH740/CH1000 engine has an oil capacity of 1.9 liters.

What is the displacement of the Kohler CH740/CH1000?

The Kohler CH740/CH1000 has a displacement of 0.0725 liters with 2 cylinders.

Which generators use the Kohler CH740/CH1000 engine?

The Kohler CH740/CH1000 powers 1 generator set(s), including Kohler RDC2.

What is a common problem with the Kohler CH740/CH1000 engine?

A commonly reported issue on generators using the Kohler CH740/CH1000 is: Under Voltage Paralleled. Fix: Press AUTO or OFF *.