Tech Tips
Use the table below to help determine the cause of the problem symptom. 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 | ||
| VC output circuit | ||
| ECT sensor | - | |
| Difficult to start with cold engine | Engine difficult to start or stalling | |
| Starter signal circuit | ||
| Pre-heating control circuit | ||
| Fuel injector assembly | ||
| Fuel filter assembly | ||
| Compression | ||
| VC output circuit | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Diesel throttle body assembly | ||
| EDU (relay) | ||
| Battery deteriorated | - | |
| Fuel with low cetane number used | - | |
| Fuel frozen | - | |
| Air mixed into fuel pipe | - | |
| Difficult to start with warm engine | Engine difficult to start or stalling | |
| Starter signal circuit | ||
| Fuel injector assembly | ||
| Fuel filter assembly | ||
| Compression | ||
| VC output circuit | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Diesel throttle body assembly | ||
| EDU (relay) | ||
| Air mixed into fuel pipe | - | |
| Battery deteriorated | - | |
| Engine stalls soon after starting | Engine difficult to start or stalling | |
| Fuel filter assembly | ||
| Fuel injector assembly | ||
| ECM power source circuit | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Diesel throttle body assembly | ||
| Air mixed into fuel pipe | - | |
| Engine stalling (not including the condition listed above) | Engine difficult to start or stalling | |
| Abnormal initial idling (poor idling) | Rough idling or excessive engine vibration | |
| Fuel filter assembly | ||
| Fuel injector assembly | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Mass air flow meter deteriorated | - | |
| Fuel with low cetane number used | - | |
| A/Cs signal circuit to ECM open and generators signal circuit to ECM open | - | |
| Low quality fuel | - | |
| High engine idling speed (poor idling) | Rough idling or excessive engine vibration | |
| A/C signal circuit | - | |
| Fuel injector assembly | ||
| Starter signal circuit | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Speed sensor circuit open | ||
| Accelerator pedal rod assembly (Accelerator link assembly) | ||
| Low engine idling speed (poor idling) | Rough idling or excessive engine vibration | |
| A/C signal circuit | - | |
| Fuel injector assembly | ||
| EGR system | ||
| Compression | ||
| Valve clearance | ||
| Fuel line (air bleeding) | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Diesel throttle body assembly | ||
| Mass air flow meter deteriorated | - | |
| Rough idling (poor idling) | Rough idling or excessive engine vibration | |
| Hunting with hot engine (poor idling) | Fuel injector assembly | |
| ECM power source circuit | ||
| Compression | ||
| Fuel line (air bleeding) | ||
| Valve clearance | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Diesel throttle body assembly | ||
| Hunting with cold engine (poor idling) | Fuel injector assembly | |
| ECM power source circuit | ||
| Compression | ||
| Fuel line (air bleeding) | ||
| Valve clearance | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Diesel throttle body assembly | ||
| Fuel with low cetane number used | - | |
| Hesitation / Poor acceleration (poor driveability) | Lack of power or hesitation | |
| Fuel injector assembly | ||
| Fuel filter assembly | ||
| EGR system | ||
| Compression | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Diesel throttle body assembly | ||
| Accelerator pedal rod assembly (Accelerator link assembly) | ||
| Turbocharger system | ||
| Mass air flow meter deteriorated | - | |
| Intake system blockage | - | |
| Exhaust system blockage | - | |
| Knocking (poor driveability) | Engine knocking or rattling | |
| Black smoke emitted (poor driveability) | Black smoke emitted | |
| EGR system | ||
| Fuel injector assembly | ||
| Accumulation in exhaust system | - | |
| Exhaust system blockage | - | |
| White smoke emitted (poor driveability) | EGR system | |
| Fuel injector assembly | ||
| Fuel filter assembly | ||
| ECM | ||
| Suction control valve | ||
| Fuel pressure sensor | ||
| Diesel throttle body assembly | ||
| Pre-heating control circuit | ||
| Low quality fuel | - | |
| Surging / Hunting (poor driveability) | Fuel injector assembly | |
| ECM | ||
| Mass air flow meter deteriorated | - | |
| Suction control valve | ||
| Fuel pressure sensor | ||
| Turbocharger system (VN turbo vane movement is detective) |