Mechanical problems such as poor fuel quality or improperly adjusted valves can cause some symptoms. Electrical problems such as open circuits or other wiring problems can cause some symptoms.
For basic troubleshooting of the engine, perform the following steps first in order to diagnose a malfunction.
- Gather the following information about the complaint from the operator:
- The occurrence and the time of the occurrence
- Determine the conditions for the occurrence. The conditions will include the engine rpm and the load.
- Determine if there are any systems that were installed by the dealer or by the customer that could cause the symptom.
- Determine whether any other occurrences happened in addition to the symptom.
- Verify that the complaint is not due to normal engine operation. Verify that the complaint is not due to error of the operator.
- Look for mechanical problems. Perform a visual inspection according to the applicable Operation and Maintenance Manual.
- Look for problems with the electrical systems. This is especially important for problems that are intermittent.
The majority of electrical problems are caused by problems with a wiring harness or with a connector. Sometimes, an open circuit may not be detected by the Electronic Control Module (ECM). Also, wires that are installed into the wrong terminals may not be detected by the ECM.
Carefully inspect the harnesses and the connectors according to Troubleshooting, "Inspecting Electrical Connectors".
- If these inspections do not reveal any problems, identify the diagnostic codes or event codes that might be caused by the symptom.
For example, Caterpillar Electronic Technician (ET) may display a value for boost pressure when the engine is not running. In this example, you would refer to the diagnostic codes or the event codes for the boost pressure sensor. Refer to Troubleshooting, "Troubleshooting With A Diagnostic Code", if necessary. Check each probable cause according to the tests that are recommended.