Cummins/Onan B3.3 Engine Engine

• The wire between ECM TB1-8 and starter solenoid terminal SW is loose, damaged or missing.
  Fix: Push the Run-Stop-Remote switch to Run and check for battery voltage (12 VDC) at starter solenoid terminal SW. If there is no voltage repair the wiring as necessary.
• The Time Delay Start/Stop Module (A15) is malfunctioning.
  Fix: Check for constant B+ at A15 terminal TB1-4. Check for run signal at ECM TB1-5. Voltage at A15 TB1-6 should be at B+ at the end of the start delay period. Check wiring and connections from A15 TB1-6 to ECM TB1-6.
• The starter motor or solenoid is malfunctioning.
  Fix: Push the Run-Stop-Remote switch to Run and check for battery voltage (B+) at starter solenoid terminal SW. Replace the starter motor if there is voltage but the motor does not function.
• The Run-Stop-Remote switch (S12) or wiring is faulty.
  Fix: A. Disconnect pin connector J4 from the ECM and check for electrical continuity (zero ohms) between switch terminals 2 and 3 when the switch is in the Run position and between terminals 1 and 2 when it is in the Remote position. Replace the switch if either set of contacts is faulty. b. If the switch works, check for electrical continuity (zero ohms) between J4-6 and J4-7 on the wire harness when the switch is in the Run position and between J4-5 and J4-7 when the switch is in the Remote position. Repair the wire harness if there is no electrical continuity in either position of the switch.
• The grounding strap between the control box and the battery negative (–) terminal or the ground wire between the control and engine ground is loose, damaged or missing.
  Fix: Check for continuity (zero ohms) between the grounding stud on the bottom of the control box and the battery negative (–) terminal. If there is no continuity or the grounding strap is loose or damaged, repair as necessary.
• The FAULT 1 or FAULT 2 fault lamp lights. Engine shuts down immediately, engine runs for several seconds and then shuts down, or engine continues to run. FAULT 1
  Fix: The standard undesignated fault functions are programmed to shut down the set when a fault is sensed.
• The engine does not crank in RUN mode.
  Fix: 1. The Run-Stop-Remote switch is at Stop. (The Switch-Off light will be flashing, if provided.) Push the Run-Stop-Remote switch to Remote. 2. The Emergency Stop switch has been used. (The switch button is lit.) Pull the Emergency Switch button. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Remote. 3. A Fault Shutdown is being indicated by one of the red lights on the control panel. Service the set as necessary. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Remote. 4. There is no remote circuit signal (12 VDC at auxiliary relay board A28-TB1-6) because fuse F3 on the ECM has blown. a. Replace the fuse with one of the same type and amp rating (15 A). b. If fuse F3 blows again, find and repair the fault in the remote control circuit, such as a loose wire that may be shorting to ground or a shorted relay coil or other component. See Section 8 for remote connections. 5. There is no remote circuit signal (12 VDC at auxiliary relay board A28-TB1-6) because the remote circuit is not functioning properly. Apply 12 VDC to A28-TB1-6. If the engine cranks, find and repair the fault in the remote control circuit. See Section 8 for remote connections. 6. Auxiliary relay board A28 is not functioning properly. Check for misconnections (see Section 8) or loose connections and replace auxiliary relay board A28 if there is 12 VDC at terminal A28-TB1-6 but not at A28-J2-6. 7. Same as Steps 3 through 11 in the RUN mode. See steps 3 through 11 in the preceding RUN mode.
• The engine cranks but does not start.
  Fix: 1. The engine is not getting fuel. a. Open any closed fuel shutoff valve. b. Fill the main fuel supply tank. c. Restore fuel pump prime according to the engine service manual. 2. Fuse F2 on the ECM has blown. Replace fuse with one of the same type and amp rating. If fuse F2 blows again, the wire between ECM TB1-10 and engine block terminal T26, or a wire between terminal T26 and an accessory may be loose or shorting to ground. 3. Fuel solenoid K1 does not energize.
• The Emergency Stop switch has been used.
  Cause: The switch button is lit.
  Fix: Pull the Emergency Switch button. To reset the engine control, push the Run-Stop-Remote switch to Stop and the Reset switch to Reset. Then push the Run-Stop-Remote switch to Run.
• The ECM is faulty.
  Fix: Push the Run-Stop-Remote switch to Run and check for battery voltage (12 VDC) at ECM TB1-8. Replace ECM if there is no voltage at ECM TB1-8 but 12 VDC at ECM TB1-9.
• SWITCH OFF lamp flashes.
  Fix: Indicates Run/Stop/Remote switch is in the Stop position which will prevent automatic starting if an automatic transfer switch is used. Move the Run/Stop/Remote switch to the Remote position for automatic starting.
• RUN or fault lamp(s) does not light when Lamp Test switch is engaged. 18
  Fix: Contact an authorized service center for assistance.
• Remote circuit breaker is tripped. 14
  Fix: Reset breaker and restart. Contact an authorized service center if breaker trips after resetting.
• PRE LO OIL PRES lamp lights. Engine continues to operate. (Engine can be programmed to shut down.)
  Fix: Indicates engine oil pressure has dropped to 20 psi (138 kPa). If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow step 5 procedure. If engine can be stopped, follow procedures in step 5.
• PRE HI ENGINE TEMP lamp lights.
  Fix: Indicates engine has begun to overheat and engine temperature has risen to approximately 220°F (104° C) or coolant level is low on optionally wired sets. If generator is powering non-critical and critical loads and cannot be shut down, use the following: a. Reduce load if possible by turning off non-critical loads. b. Check air inlets and outlets and remove any obstructions to airflow. If engine can be stopped, follow procedure in step 3.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan B3.3.

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

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.