P027A

Code

Generic P — Powertrain

Fuel Pump Module B Control Circuit/Open

Brand: Generic

Type: P — Powertrain

Views: UK: 16 EN: 91 RU: 18

AI status

Completed

ready

Completed 100%

Page language: EN

Read and record freeze frame data and stored codes; note conditions when fault set
Visually inspect wiring harness, connectors, pins, and protective conduit to pump B
Check fuel pump-related fuses and relays for continuity and correct operation
Check battery voltage at the time of test (low battery can mask signals)
Backprobe connector at pump B and at ECM to check for control voltage and continuity
Measure resistance of pump module B power/ground circuits (with battery disconnected)

Control wire expected behavior: open-circuit (no voltage) when fault present; normally switched battery voltage or PWM from ECM when commanded
Typical command voltage: approximately 0–12 V (closed = ~12 V, open = 0 V) or PWM 0–100% duty at tens to low hundreds Hz depending on vehicle
Expected pump current draw when running: typically 2–15 A (varies by vehicle and pump type)—check manufacturer spec
Typical pump module winding resistance: often below 5 ohms; open/infinite resistance indicates internal open
Good ground: near 0 ohms between module ground terminal and chassis ground

Retrieve all DTCs and freeze-frame data. Confirm P027A is current and note conditions (key on, cranking, driving).
Visually inspect the pump B connector and wiring for corrosion, bent pins, or water intrusion. Repair obvious damage.
With ignition OFF, disconnect the pump B connector. Check connector for continuity to the ECM control pin and to battery/ground as applicable using wiring diagram.
Check relevant fuse(s) and relay(s). Replace suspect fuses/relays and re-test.
With a DVOM, measure resistance of pump B supply and ground circuits (battery disconnected). Infinite resistance on supply or ground indicates open circuit.
With battery connected and key ON (engine off), backprobe the pump B control wire. Command the pump ON via scan tool and observe for expected voltage or PWM. If no signal, trace back to ECM.
If control signal is present at ECM but absent at pump connector, isolate and repair open in wiring harness (splice, replace section, repair connector).
If control signal is absent at ECM output, verify ECM grounds and power. Consider ECM driver fault only after wiring and pump tested good.
If wiring and command are good but pump shows open winding (infinite ohms) or does not run when directly applied with battery, replace Fuel Pump Module B.
After repair, clear codes, perform functional test (prime, start, road test) and verify code does not return. Re-scan for pending codes.