P2A73

Code

Generic P — Powertrain

Alternative Fuel Hydraulic Fuel Pump Select Valve Control Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 28 RU: 22

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Page language: EN

Causes

Short to battery power (B+) on the valve control circuit
Damaged or corroded connector or wiring (insulation worn through, pins stuck)
Failed valve solenoid or actuator with internal short
Faulty valve driver/transistor inside the ECM/PCM
Poor or missing ground in related circuit causing abnormal voltage reading
Aftermarket modifications or incorrect replacement parts

Symptoms

Malfunction indicator lamp (MIL) or check engine light illuminated
Alternative fuel selection may not operate or switch properly
Reduced performance or limp-home mode on alternative fuel
Intermittent operation of the fuel pump selector or valve
Stored fault codes related to select valve control

What to check

Read freeze frame and full DTC list; note conditions when code set
Inspect harness and connector at the select valve for corrosion, damage, or water
Visually inspect wiring along the harness for chafing or repairs
Measure battery voltage with engine off and running to ensure stable supply
Backprobe the control connector and monitor voltage while commanding the valve on/off
Measure coil resistance of the select valve solenoid with harness disconnected

Signal parameters

Resting/command-off voltage: near 0 V (ground) on the control circuit or open/low driver condition
Command-on voltage: switches toward battery voltage (up to vehicle battery voltage) or PWM from ECM (0–12 V range depending on design)
Typical control signals may be a PWM duty cycle at controller-specified frequency; expected current draw usually in the small ampere range (verify specification)
High-voltage condition: sustained voltage near battery voltage on the control pin when the ECM expects low or ground

Diagnostic algorithm

Retrieve codes and freeze frame data. Note operating conditions (engine on/off, temperature, fuel mode).
Visually inspect valve connector and wiring for obvious damage, corrosion, or water intrusion. Repair any visible damage before further testing.
With connector attached, backprobe the control lead. Command the valve ON from a scan tool and observe the signal. Note whether voltage goes high or is stuck high.
With ignition ON and engine OFF, measure voltage at the control pin. Compare to battery voltage. If the control circuit is battery voltage with no command, suspect a short to B+ or stuck power feed.
Disconnect the valve connector. Measure resistance of the valve coil to ground and between coil terminals. Compare to manufacturer spec (if unknown, check for open or very low resistance indicating short).
Check continuity between the control circuit and the ECM connector for unexpected continuity to B+ or short to ground. Wiggle harness while monitoring to find intermittent faults.
Verify ECM ground(s) and supply voltage are within specification. Inspect ECM connector pins for damage.
If wiring and valve check good, capture the output of the ECM while commanding the valve. If the ECM output is failing (stuck high), consider ECM repair/replacement following manufacturer guidance.
Replace the faulty wiring, connector, or valve as indicated by tests. If ECM is suspected, confirm all other possibilities before replacing; follow proper programming/replacement procedures.
Clear codes and perform a functional test / road test to confirm the fault does not return.

Likely causes

Shorted wire to battery between ECM and valve connector
Corroded connector causing high resistance/erratic voltage
Faulty select valve solenoid with internal short to battery
Defective ECM/PCM output stage driving the valve

Fault status

⚠️ Status

Control circuit voltage for alternative-fuel hydraulic fuel pump select valve is higher than expected — possible short to battery, faulty valve or driver, or wiring/connectors compromised.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours