Engine Speed Surges in PTO or Cruise Control

Symptom Tree  t068

This is symptom tree t068
Cause Correction

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF for fault code troubleshooting.

 

Engine speed also surges at idle

Refer to the Engine Speed Surges at Low or High Idle symptom tree.

 

Cruise control/PTO on/off switch or circuit is malfunctioning

Check the cruise control/PTO on/off switch and the circuit. Refer to Procedures 019-021 and 019-022.

 

Moisture in the wiring harness connectors

Dry the connectors with Cummins electronic cleaner, Part Number 3824510.

 

Engine position sensor (EPS) or circuit is malfunctioning

Check the engine position sensor and circuit. Refer to Procedures 019-038 and 019-039.

 

Vehicle speed sensor (VSS) or circuit is malfunctioning

Check the vehicle speed sensor and circuit. Refer to Procedures 019-090 and 019-091.

 

Tailshaft gear is loose

Check for a loose tailshaft gear. Refer to the OEM service manuals.

 

Alternator is malfunctioning

Temporarily disconnect the alternator and run the engine. Replace the alternator if necessary. Refer to the OEM service manuals.

 

Vehicle ground circuit has an intermittent open circuit

Check the ground circuit for loose or broken connections. Refer to the OEM service manuals.

 

Fuel pump is malfunctioning

Check the fuel pump output pressure, pulsation damper, and pressure regulator. Replace the fuel pump if necessary. Refer to Procedures 005-011, 005-016, and 005-031 in the Troubleshooting and Repair Manual N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

Electronic control module (ECM) calibration is malfunctioning

Verify the ECM calibration is correct. Check the calibration revision history for applicable fixes to the calibration stored in the ECM. Refer to the calibration history spreadsheet Click here to see ecm_calibration_rev_history.xls

on QuickServe® Online or the INCAL™ CD-ROM. Compare the calibration stored in the ECM with the engine rating and the Control Parts List (CPL), Bulletin 4021326 or 4021327. If necessary, recalibrate the ECM. Refer to the appropriate electronic service tool manual and Procedure 019-032.

 
Last Modified:  02-Feb-2004

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