Code
P224C
Generic
P — Powertrain
Alternative Fuel Tank Shutoff Valve A Control Circuit/Open
AI status
Completed
Completed
100%
Causes
- Open or high-resistance wiring in the valve control circuit
- Poor or corroded connector at the shutoff valve
- Blown fuse or failed relay supplying the valve circuit
- Failed Alternative Fuel Tank Shutoff Valve A (coil open)
- Faulty ECM or ECM driver circuit
- Water intrusion or physical damage to wiring harness
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Alternative fuel system may not switch or operate correctly
- No audible click or action from the shutoff valve when commanded
- Possible reduced drivability or inability to use alternative fuel source
- Stored DTC(s) and possibly limp-mode depending on system design
What to check
- Retrieve freeze frame and readiness data with a scan tool; note conditions when code set
- Visual inspection of valve, connector, and wiring for damage, corrosion, or contamination
- Check relevant fuses and relays for the valve circuit
- Backprobe valve connector while commanding valve ON/OFF to verify voltage and ground
- Measure valve coil resistance at the connector with harness disconnected
- Perform continuity check between ECM control pin and valve connector
Signal parameters
- Expected OFF voltage at control pin: ~0 V (no command) or low voltage if ECM uses low-side drive
- Expected ON: switched to battery voltage or driven by PWM — nominally near battery (10–14 V) or pulsed at a variable duty cycle
- Valve coil resistance (typical): approx. 10–50 ohms (vehicle-specific; measure actual component spec)
- Current draw when energized: commonly 0.2–2.0 A depending on valve design
- Continuity: near zero ohms between connector terminals for coil; open = OL/infinite
Diagnostic algorithm
- Connect a scan tool, read and record all stored codes and freeze-frame data. Confirm P224C is current and note commanded state of valve.
- Perform visual inspection of valve, connector, and visible wiring. Repair any obvious damage or corrosion before further testing.
- Locate and verify relevant fuses and relays are intact and supplying power. Replace if blown or faulty.
- With ignition ON (engine off), backprobe the valve connector. Command the valve ON from the scan tool and observe voltage at the power and control pins. Record measurements.
- Measure coil resistance at the valve connector with ignition OFF. Compare to specification or expected range. Infinite/open indicates a failed coil.
- Check continuity between the ECM control pin and the valve control terminal. Repair any open or high-resistance sections in the harness.
- If voltage is present at harness but valve does not operate, bench-test the valve by applying appropriate voltage to confirm mechanical operation. Replace valve if it fails.
- If valve and wiring check OK but no control signal from ECM, inspect ECM connector for corrosion or damage. Test ECM driver output per manufacturer procedures; consider ECM replacement only after ruling out harness and component faults.
- After repairs, clear codes, perform functional test and a short drive cycle to confirm the code does not return.
Likely causes
- Broken or pinched harness conductor between ECM and valve
- Faulty valve coil with infinite or very high resistance
- Connector terminal pulled out, corroded, or backed out
- Inline fuse blown or relay contacts failed
- Intermittent open caused by movement/wiring chafe
- ECM output transistor failed (less common)
Fault status
Status
Alternative Fuel Tank Shutoff Valve A Control Circuit/Open — ECM detected an open or no-control condition on the valve A control circuit.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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