Code
P1280
PLYMOUTH
P — Powertrain
Open Or Shorted Condition Detected In The Fuel System Relay Control Circuit
AI status
Completed
Completed
100%
Causes
- Blown fuse or fusible link for fuel pump/relay circuit
- Failed fuel pump relay
- Open or shorted wiring in relay control or power feed circuit
- Corroded or loose connector(s) at relay, fuel pump, or PCM
- Poor or corroded ground(s)
- Aftermarket alarm/immobilizer or recent wiring modification/repair
Symptoms
- No-start or crank-no-start condition
- Engine cranks but fuel pump does not prime
- Intermittent stalling or no fuel pressure
- MIL (Check Engine Light) illuminated
- No audible fuel pump run during key-on (prime) in many cases
What to check
- Verify battery voltage and good main battery connections
- Check fuel pump fuse(s) and fusible link(s) for continuity
- Listen for fuel pump prime with key ON; try known-good relay to substitute
- Inspect relay socket and wiring for corrosion, damage or loose pins
- Scan for additional DTCs and view freeze-frame / fuel pump control status
- Measure voltage at relay power feed and at control terminal during key ON/engine cranking
Signal parameters
- Relay power feed terminal: battery voltage with key ON (~12 V).
- Relay control terminal: should switch between ~0 V (ground-switched) or ~12 V (power-switched) as defined by vehicle wiring; consult service manual to confirm expected polarity.
- When control is commanded ON, measured voltage/current should be consistent with relay coil spec (relay coil resistance typically in the tens to low hundreds of ohms; check relay label/service data).
- Fuel pump current draw when running: varies by vehicle; expect a few amps (reference pump spec).
- Continuity: low ohms between relay control terminal and PCM driver pin when circuit intact; open = infinite/very high ohms.
Diagnostic algorithm
- Retrieve stored codes and freeze-frame data; note any related codes. Clear codes and attempt to re-create the condition to verify persistence.
- Confirm basic items: battery charged, main fuses and fusible links intact for fuel/fuel pump circuits.
- With key ON (engine OFF) listen for pump prime. If no prime, have a helper operate starter or use scan tool to command pump ON while monitoring relay.
- Visually inspect relay, relay socket, connectors, and wiring for heat damage, corrosion, rodent chew, or water intrusion. Repair obvious issues.
- Swap the fuel pump relay with a known-good relay of same type (if available) to see if condition clears.
- Backprobe relay terminals: verify constant battery voltage at relay feed, and measure control terminal while PCM commands the pump. If control terminal shows neither expected ground nor supply voltage, trace/control wire to PCM.
- Check continuity between relay control terminal and PCM connector pin; repair any open circuit. Check for shorts to battery or ground if control terminal reads unexpected voltage.
- Test fuel pump directly (bench or by safely jumpering power) to confirm pump operation. Only perform safe, approved methods and relieve pressure first if necessary.
- If wiring and pump/relay are good but control signal is absent or erratic, inspect PCM connector for bent pins and consider PCM driver failure; consult manufacturer service manual before replacing module.
- After repairs, clear codes and perform road test/operate several key cycles to ensure code does not return.
Likely causes
- Failed or intermittent fuel pump relay
- Blown fuse or fusible link in feed to relay
- Open/short in relay control wire between relay and PCM
- Corroded/loose relay connector or ground
- PCM driver fault (less common)
Fault status
Status
Open or short detected in fuel system relay control circuit. Possible faulty relay, wiring, fuse, or PCM driver. Fuel pump may not run; vehicle may not start or may stall.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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