Troubleshooting

An electrical fault can prevent the electronic unit
injector from operating. An open circuit or a short
circuit in the ECM that is unique to one electronic unit
injector will prevent that electronic unit injector from
operating. An open circuit or a short circuit in
common wiring within the ECM can prevent the two
electronic unit injectors that share that common
wiring from operating. Injector 1 and injector 4 share
common wiring within the ECM. Injector 2 and
injector 3 share common wiring within the ECM.
Perform this procedure under conditions that are
identical to the conditions that exist when the fault
occurs. Typically, faults with the injector solenoid
occur when the engine is warmed up and/or when the
engine is under vibration (heavy loads).
These engines have Electronic Unit Injectors (EUI).
The ECM sends a pulse to each injector solenoid.
The pulse is sent at the correct time and at the
correct duration for a given engine load and speed.
The solenoid is mounted on top of the fuel injector
body.
If an open circuit is detected in the solenoid circuit, a
diagnostic code is generated. The ECM continues to
try to fire the injector. If a short circuit is detected, a
diagnostic code is generated. The ECM will
periodically try to fire the injector. If the short circuit
remains, this sequence of events will be repeated
until the fault is corrected.
Illustration 32 g03616577
Schematic of the circuit for the injector solenoids
Not all connectors are shown. Refer to the electrical schematic for the engine.
154 UENR0612-07
Circuit Tests
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