Fuel Pump Electrical Circuit Diagnosis
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Fuel Pump Electrical Circuit Diagnosis
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Diagnostic Fault Information
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Circuit
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Short to Ground
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Open or High Resistance
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Short to Voltage
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Signal Performance
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Fuel Pump High Signal
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P0231
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P023F
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P0232
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P023F, P2635
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Fuel Pump Low Signal
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-
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P023F
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-
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P023F, P2635
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Circuit/System Description
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The engine control module (ECM) supplies voltage to the fuel pump control module when the ECM detects that the ignition is on. The voltage from the ECM to the fuel pump control module remains active for two seconds, unless the engine is in crank or run. While this voltage is being received, the fuel pump control module closes the ground switch of the fuel pump and also supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel rail pressure.
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Fuel System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
for scan tool information
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Circuit/System Verification
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Ignition ON, command the fuel pump ON and OFF using the scan tool ECM output control. The fuel pump should turn ON and OFF.
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1.
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Ignition OFF, disconnect the harness connector at the G12 fuel pump.
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2.
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Connect a test lamp between the control circuit terminal 1 and ground.
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3.
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Ignition ON, command the G12 fuel pump ON and OFF using a scan tool ECM fuel pump output control. The test lamp should turn ON and OFF, as commanded.
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4.
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If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K27 Fuel Pump Control Module.
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5.
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If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K27 Fuel Pump Control Module.
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6.
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Ignition OFF, connect a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
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7.
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Ignition ON, command the G12 fuel pump ON using a scan tool. The test lamp should turn ON.
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8.
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If the test lamp does not illuminate, test the low reference circuit terminal 1 for a short to earth or an open/high resistance. If the circuit tests normal, replace the K27 fuel pump control module.
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9.
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If all circuits test normal, replace the G12 fuel pump.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Control Module References
for fuel pump control module replacement, setup, and programming
