Tech Tips
Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table.
Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
| Symptom | Suspected Area | See page |
|---|---|---|
| Engine does not crank (does not start) | Starter | |
| Starter relay | ||
| Starter signal circuit | ||
| No initial combustion (does not start) | ECM power source circuit | |
| Pre-heating control circuit | ||
| Compression | ||
| ECM | ||
| Fuel injection pump | ||
| VC output circuit | ||
| Difficult to start (cold engine) | Pre-heating control circuit | |
| Starter signal circuit | ||
| Engine coolant temperature sensor | ||
| Fuel injection nozzle | ||
| Fuel filter element assembly (level warning switch) | ||
| Diesel throttle body | ||
| ECM | ||
| Fuel injection pump | ||
| Difficult to start (hot engine) | Starter signal circuit | |
| Fuel injection nozzle | ||
| Fuel filter element assembly (level warning switch) | ||
| Diesel throttle body | ||
| ECM | ||
| Fuel injection pump | ||
| Engine stall (soon after starting) | Fuel filter element assembly (level warning switch) | |
| Diesel throttle body | ||
| ECM | ||
| Fuel injection pump | ||
| Engine stall (other) | ECM power source circuit | |
| Diesel throttle body | ||
| ECM | ||
| Fuel injection pump | ||
| Incorrect first idle (poor idling) | Engine coolant temperature sensor | |
| Fuel filter element assembly (level warning switch) | ||
| ECM | ||
| Fuel injection pump | ||
| High engine idle speed (poor idling) | Air conditioning signal circuit | |
| Engine coolant temperature sensor | ||
| ECM | ||
| Fuel injection pump | ||
| Low engine idle speed (poor idling) | Air conditioning signal circuit | |
| Fuel injection nozzle | ||
| Engine coolant temperature sensor | ||
| Diesel throttle body | ||
| Compression | ||
| Valve clearance | ||
| Fuel line (air bleed) | ||
| ECM | ||
| Fuel injection pump | ||
| Rough idling (poor idling) | Fuel injection nozzle | |
| Fuel line (air bleed) | ||
| Pre-heating control circuit | ||
| Diesel throttle body | ||
| Compression | ||
| Valve clearance | ||
| ECM | ||
| Fuel injection pump | ||
| Hunting when engine is hot (poor idling) | Fuel injection nozzle | |
| ECM power source circuit | ||
| Compression | ||
| Fuel line (air bleed) | ||
| Valve clearance | ||
| ECM | ||
| Fuel injection pump | ||
| Hunting when engine is cold (poor idling) | Pre-heating control circuit | |
| Fuel injection nozzle | ||
| ECM power source circuit | ||
| Engine coolant temperature sensor | ||
| Compression | ||
| Fuel line (air bleed) | ||
| Valve clearance | ||
| ECM | ||
| Fuel injection pump | ||
| Hesitation/Poor acceleration (poor driveability) | Fuel injection nozzle | |
| Fuel filter element assembly (level warning switch) | ||
| Compression | ||
| ECM | ||
| Fuel injection pump | ||
| Brake override system | ||
| Knocking (poor driveability) | Fuel injection nozzle | |
| Engine coolant temperature sensor | ||
| ECM | ||
| Black smoke (poor driveability) | Fuel injection nozzle | |
| Diesel throttle body | ||
| Intake air temperature sensor | ||
| ECM | ||
| Fuel injection pump | ||
| White smoke (poor driveability) | Pre-heating control circuit | |
| Fuel injection nozzle | ||
| Fuel filter element assembly (level warning switch) | ||
| Diesel throttle body | ||
| Engine coolant temperature sensor | ||
| Intake air temperature sensor | ||
| ECM | ||
| Fuel injection pump | ||
| Surging/Hunting (poor driveability) | Fuel injection nozzle | |
| ECM | ||
| Fuel injection pump |