General Troubleshooting Information

Troubleshooting engine problems can be difficult. An engine wiring diagram is provided in this section to help isolate electrical problems on power units using John Deere wiring harness and instrument (gauge) panel.

Later in this section is a list of possible engine problems that may be encountered accompanied by possible causes and corrections. The illustrated diagrams and troubleshooting information are of a general nature; final design of the overall system for your engine application may be different. See your engine distributor or servicing dealer if you are in doubt.

A reliable program for troubleshooting engine problems should include the following basic diagnostic thought process:

• Know the engine and all related systems.
• Study the problem thoroughly.
• Relate the symptoms to your knowledge of engine and systems.
• Diagnose the problem starting with the easiest things first.
• Double-check before beginning the disassembly.
• Determine cause and make a thorough repair.
• After making repairs, operate the engine under normal conditions to verify that the problem and cause was corrected.

NOTE: All engines have electronic control systems which may send diagnostic trouble codes to signal problems (see Displaying Of Diagnostic Trouble Codes (DTCs), later in this section).

1. If fault codes are present, perform the suggested corrective actions.
2. If this does not correct the engine problem, contact your servicing dealer.
3. If engine has problems but no fault codes are displayed, refer to ENGINE TROUBLESHOOTING later in this section for problems and solutions.