P025B

Code

Generic P — Powertrain

Fuel Pump Module A Control Circuit Range/Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 27 EN: 103 RU: 29

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty fuel pump module (internal driver or pump motor)
Open, shorted or high-resistance wiring in the pump control circuit
Corroded or loose connector at the fuel pump module
Faulty fuel pump relay, fuse or power supply
Poor ground at fuel pump module
PCM/FPDM (fuel pump driver module) or software fault

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Hard starting, long crank or no-start
Intermittent stalling or loss of power under load
Poor acceleration or reduced engine performance
Fuel pressure low, erratic or out of specification
Unusual noise from fuel tank (when pump commanded)

What to check

Read freeze frame and readiness data; note conditions when code set
Scan for related DTCs (fuel pressure, pump control, CAN/communication codes)
Verify fuses and fuel pump relay operation
Inspect connector at fuel pump module for corrosion, water, bent pins or loose mates
Backprobe control and power circuits at pump connector while reproducing fault
Monitor live data: fuel pump command (duty cycle or ON/OFF), fuel rail pressure, battery voltage

Signal parameters

Control signal type: PWM (duty cycle) or switched ON/OFF depending on vehicle — expected range 0–100% duty (exact freq and duty vary by make/model)
When commanded ON, voltage at pump power terminal should be approximately battery voltage (approx. 11–14.5 V with engine running)
Pump motor DC resistance: typically low (ohms range). Exact spec varies by model — compare to manufacturer spec
Pump current draw while running: commonly several amps (typical 4–20 A depending on pump/engine); excessive or very low current indicates fault
Fuel rail pressure should be within manufacturer specification under commanded conditions (varies by engine/load)

Diagnostic algorithm

Record freeze frame and other DTCs. Clear codes and attempt to reproduce with known conditions (key ON/crank/drive).
Visually inspect pump module connector and wiring for corrosion, damage, pin push out, or water intrusion. Repair any obvious issues.
Verify fuses and relay for fuel pump circuit; substitute relay if uncertain. Check for proper relay control from PCM.
Monitor live data: fuel pump command (duty or status), fuel rail pressure, and battery voltage while reproducing. Note discrepancies.
Backprobe pump connector: measure supply voltage and control signal while commanded. Confirm control signal duty/frequency and battery voltage presence.
Measure pump motor resistance at module connector and compare to spec. Check for open, short, or high resistance.
Measure pump current while running. Low or no current indicates open circuit or failed pump; excessive current indicates mechanical bind or short.
Perform wiggle test on wiring harness and connector while observing live data/pressure to find intermittent faults.
If wiring and power are good but control signal or driver behavior is abnormal, evaluate fuel pump driver module or PCM output. Check for related CAN/communications issues.
If bench testing indicates pump failure or internal driver failure, replace fuel pump module and retest. After repair, clear codes and verify proper operation under load.

Likely causes

Corroded/loose connector or damaged wiring between PCM/FPDM and pump module
Failed fuel pump module (internal driver or motor degradation)
Faulty fuel pump driver module or PCM output transistor
Blown fuse or faulty relay in pump supply circuit

Fault status

⚠️ Status

PCM detected fuel pump module A control circuit performance outside expected range — check pump module, wiring/connectors, power/ground, and fuel pressure.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours