Symptom Tree t068
| Cause | Correction |
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Electronic fault codes active or high counts of inactive fault codes |
Refer to Section TF for fault code troubleshooting. |
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Verify the complaint |
Test the engine operation while under load. Perform an engine acceleration test. Perform an engine load/install test. Refer to Procedure 014-002 in the Troubleshooting and Repair Manual, C8.3G, C Gas Plus and L Gas Plus Engines, Bulletin 3666206 or Procedure 014-002 in the Troubleshooting and Repair Manual, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin 3666164. If engine has low or high power, refer to the Engine Power Output is Low or Engine Power Output is High symptom tree. |
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Engine speed also surges at idle |
Refer to the Engine Speed Surges at Low or High Idle symptom tree. |
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Engine speed surges while in the normal operating range and not in PTO or cruise control |
Refer to the Engine Speed Surges Under Load or in Operating Range symptom tree. |
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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 Procedure 019-032. |
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Vehicle speed sensor (VSS) or circuit is malfunctioning |
Use an electronic service tool to monitor the vehicle speed while the vehicle is not moving. Refer to the appropriate electronic service tool manual. If the monitor shows speed, check the sensor and circuit. Refer to Procedure 019-090 or 019-091. |
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Moisture in the wiring harness connectors |
Dry the connectors with Cummins electronic cleaner, Part Number 3824510. Do not use on heated oxygen sensor connectors. Refer to a Cummins Authorized Repair Facility. |
