Daewoo NUBIRA, User Manual

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1F – 52 I ENGINE CONTROLS
DAEWOO V–121 BL4
FUEL PUMP RELAY CIRCUIT CHECK
Circuit Description
When the ignition switch is turned ON, the powertrain con-
trol module (PCM)/engine control module (ECM) will acti-
vate the fuel pump relay and run the in–tank fuel pump.
The fuel pump will operate as long as the engine is crank-
ing or running and the PCM/ECM is receiving ignition ref-
erence pulses.
If there are no reference pulses, the PCM/ECM will shut
off the fuel pump within 2 seconds after the ignition switch
is turned ON.
Diagnostic Aids
An intermittent problem may be caused by a poor connec-
tion, rubbed through wire insulation, or a broken wire in-
side the insulation.
Test Description
The number(s) below refer to step(s) on the diagnostic
table.
3. This step checks for the PCM/ECM providing a
ground for the operation of the fuel pump relay.
7. By confirming that the wiring is OK using Steps 2
through 6, it can be determined that the fuel pump
relay is at fault.
9. After determining that there is no ground being pro-
vided by the PCM/ECM to the fuel pump relay, the
fault is either the PCM/ECM or the wiring between
the PCM/ECM and the fuel pump relay.