121

Possible Causes

• •Cold engine
• •Corroded, bent, broken, pushed back, expanded, or loose pins
• •Dirt or debris in or on the connector pins
• •Electronic governor actuator could be bad
• •Evidence of moisture in or on the connector
• •Fault simulation was enabled with InPower
• •Fault threshold is not set correctly with InPower
• •Faulty Crankshaft Speed Sensor
• •Faulty Crankshaft Speed Sensor Connections
• •Faulty crankshaft speed sensor
• •Faulty crankshaft speed sensor connections
• •Missing or damaged connector seals
• •Moisture in or on the connector
• •Single step large block load removal
• •The electronic governor actuator could be bad

Suggested Actions

1. 1Check the crankshaft speed sensor supply voltage
2. 2Check the crankshaft speed sensor supply voltage.
3. 3Clear fault and restart genset
4. 4Determine highest allowable setting and set threshold as required
5. 5Determine highest allowable setting and set threshold as required using InPower
6. 6Disconnect the engine harness connector from the crankshaft speed sensor
7. 7Disconnect the engine harness connector from the crankshaft speed sensor.
8. 8Inspect for corroded, bent, broken, pushed back, expanded, or loose pins
9. 9Inspect for corroded, bent, broken, pushed back, expanded, or loose pins.
10. 10Inspect for dirt or debris in or on the connector pins
11. 11Inspect for dirt or debris in or on the connector pins.
12. 12Inspect for evidence of moisture in or on the connector
13. 13Inspect for evidence of moisture in or on the connector.
14. 14Inspect for missing or damaged connector seals
15. 15Inspect for missing or damaged connector seals.
16. 16Inspect or repair O-rings and pump
17. 17Inspect or repair O-rings, pump
18. 18Inspect the crankshaft speed sensor and the engine harness connector pins
19. 19Inspect the crankshaft speed sensor and the engine harness connector pins.
20. 20Install the speed sensor breakout cable between the sensor and the sensor harness connector
21. 21Install the speed sensor breakout cable between the sensor and the sensor harness connector.
22. 22Monitor engine RPM using InPower (refer to fault code 121)
23. 23Refer to fault code 121
24. 24Remove battery power from control (if InPower is not available)
25. 25Verify that fault is not enabled
26. 26Verify that fault is not enabled (if no InPower, remove battery power from control)

Related Cummins Fault Codes