G3520B Engines Caterpillar

Some engine symptoms can be unrelated to the electronic control system. This section is for troubleshooting problems that have symptoms without active diagnostic codes. Conditions such as poor fuel quality or improperly adjusted valves can cause some engine symptoms.

For basic troubleshooting of the engine, perform the following steps first in order to diagnose a malfunction.

1. Gather information about the complaint from the operator.

2. Verify that the complaint is not due to normal engine operation. Verify that the complaint is not due to error of the operator.

3. Perform a visual inspection. Inspect the following items:
   • Fuel supply

   • Oil level

   • Oil supply

   • Coolant level

   • Wiring

   • Connectors

4. Check the diagnostic codes and event codes. Repair any active codes.

If these inspections do not reveal any problems, identify the probable causes with the procedures in this manual that best describe the symptoms. Refer to Troubleshooting, "Troubleshooting With A Diagnostic Code" or refer to Troubleshooting, "Troubleshooting With an Event Code". Check each probable cause according to the tests that are recommended.

Be sure to check the connectors. This is specially true for problems that are intermittent. Refer to Troubleshooting, "Inspecting Electrical Connectors".

Narrow the probable cause. Consider the operator information, the conditions of operation, and the history of the engine.

Operator Information

Obtain the following information 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.

Diagnostic Codes and Event Codes

Examine the following information regarding any codes:

• The probable cause of the symptom is correlated to the code.

• The code was generated when the symptom occurred.

• Codes that are repeatedly logged

• The complaint is not due to normal engine operation.

Other Symptoms

If other occurrences happened in addition to the symptom, investigate the following conditions:

• The other occurrences are related to the symptom.

• The symptoms have a probable cause that is common.