Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1993ASTRO VAN L AWD V6-262 4.3L VIN W CPIREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSFUEL PUMP SIGNALDESCRIPTION AND OPERATION
1993 Chevrolet Astro Van L AWD V6-262 4.3L VIN W CPI
Fuel Pump Signal: Description and Operation
1993 Chevrolet Astro Van L AWD V6-262 4.3L VIN W CPISECTION Description and Operation
PURPOSE
The fuel pump voltage signal is used by the control module as a reference to determine fuel system electrical loading and circuit integrity.
OPERATION
The status of the fuel pump CKT 120 is monitored by the control module and is used to compensate fuel delivery based on system voltage. This signal is also used to store a DTC if the fuel pump relay is defective or fuel pump voltage is while the engine is running. There should be about 12 volts on CKT 120 for at least 2 seconds after the ignition is turned "ON" or any time reference pulses are being received by the control module.
With PCM/VCM systems DTC 54 (VCM is DTC P1222) will set if the voltage at control module fuel pump signal terminal is less than 2 volts for 1.5 seconds since the last reference pulse was received. This DTC is designed to detect a faulty relay, causing extended crank time, and the DTC will help the diagnosis of an engine that "Cranks But Will Not Run".
With ECM systems DTC 54 will set if the voltage at control module fuel pump signal terminal is less than 2 volts for 5 seconds since the last reference pulse was received. This DTC is designed to detect a faulty relay, causing extended crank time, and the DTC will help the diagnosis of an engine that "Cranks But Will Not Run".
The fuel pump voltage signal is used by the control module as a reference to determine fuel system electrical loading and circuit integrity.
OPERATION
The status of the fuel pump CKT 120 is monitored by the control module and is used to compensate fuel delivery based on system voltage. This signal is also used to store a DTC if the fuel pump relay is defective or fuel pump voltage is while the engine is running. There should be about 12 volts on CKT 120 for at least 2 seconds after the ignition is turned "ON" or any time reference pulses are being received by the control module.
With PCM/VCM systems DTC 54 (VCM is DTC P1222) will set if the voltage at control module fuel pump signal terminal is less than 2 volts for 1.5 seconds since the last reference pulse was received. This DTC is designed to detect a faulty relay, causing extended crank time, and the DTC will help the diagnosis of an engine that "Cranks But Will Not Run".
With ECM systems DTC 54 will set if the voltage at control module fuel pump signal terminal is less than 2 volts for 5 seconds since the last reference pulse was received. This DTC is designed to detect a faulty relay, causing extended crank time, and the DTC will help the diagnosis of an engine that "Cranks But Will Not Run".
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.