RENR5042-02 153 Troubleshooting Section These engines have Electronic Unit Injectors (EUI) that are mechanically actuated and electronically controlled. The Engine Control Module (ECM) sends a 105 volt pulse to each injector solenoid. The pulse is sent at the proper time and at the correct duration for a given engine load and speed. The solenoid is mounted on top of the fuel injector body. The 105 volt pulse can be individually cut out to aid in troubleshooting misfire problems. If an open is detected in the solenoid circuit, a diagnostic code is generated. The ECM continues to try to fire the injector. If a short is detected, a diagnostic code is generated.
The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains this sequence of events will be repeated until the problem is corrected. An injector trim file must be programmed into the ECM for each cylinder. Refer to troubleshooting, “Injector Trim File”. g01102462 Illustration 74 Electronic unit injector Cylinder Cutout Test (1) Solenoid (2) Injector The “Cylinder Cutout Test” is used to isolate the malfunctioning injector in order to avoid replacement of good injectors. Use the “Cylinder Cutout Test” on the Caterpillar Electronic Technician (ET) to diagnose a malfunctioning injector while the engine is running.
All active diagnostic codes must be repaired before running the “Cylinder Cutout Test”. When a good injector is cut out, the “Fuel Position” should change. The change in the fuel position is caused by the other injectors that are compensating for the cut out injector. If a malfunctioning injector is cut out, the “Fuel Position” will not change. Injector Solenoid Test The “Injector Solenoid Test” is used to isolate a malfunctioning injector in order to avoid replacement of good injectors. Use the “Injector Solenoid Test” on Cat ET to aid in diagnosing a diagnostic code while the engine is not running. The “Injector Solenoid Test” will send a signal to each solenoid.
Cat ET will indicate the status of the solenoid as “Open”, or “Short”. An open circuit or a short circuit in the common wire to two injector solenoids will cause two cylinders to have diagnostic codes.