P1660

Code

SCION P — Powertrain

Fuel cut control circuit malfunction

Brand: SCION

Type: P — Powertrain

Views: UK: 15 EN: 31 RU: 28

AI status

Completed

ready

Completed 100%

Page language: EN

Blown fuse or faulty relay in fuel cut/fuel pump circuit
Open, shorted, corroded or damaged wiring/connectors to the fuel cut solenoid/valve or ECM
Faulty fuel cut solenoid/valve (fuel cutoff valve) or associated actuator
Poor ECM power or ground connection or internal ECM fault
Intermittent connector contact (water intrusion, corrosion)
Related sensor faults causing incorrect fuel cut requests (TPS, MAP, or engine speed signal)

Malfunction Indicator Lamp (MIL) illuminated
Intermittent or permanent loss of decel fuel cut (abnormal fuel consumption during deceleration)
Rough idle, hesitation, reduced drivability under some conditions
Possible drivability limp or stalling if fuel control is affected
No cranking or no start if fuel cut remains permanently commanded

Scan for DTCs and freeze frame data; note related codes (TPS, MAP, fuel rail pressure, cam/crank sensors)
Visually inspect fuses and relays related to fuel system and ECM power/grounds
Inspect wiring and connectors at the fuel cut solenoid/valve and ECM for corrosion, damage or loose pins
Check battery voltage and main power/ground at the ECM and relevant relays while cranking and running
Wiggle test harnesses and connectors while monitoring live data or diagnostic signal to reproduce fault

Control signal type: ECM-driven on/off or PWM (duty cycle) — expect 0%–100% duty when active (refer to service manual for frequency)
Typical control voltage: 0 V (off) to near battery voltage (on) at supply side; switched/grounded control at the ECM side
Solenoid coil resistance: consult service manual for nominal ohms (measure coil resistance for open/short)
Expected battery voltage at supply pins: ~12 V with engine off/ignition on (within manufacturer-spec)

Retrieve and record all stored DTCs and freeze frame data; clear codes and perform a test drive to see if the code returns.
Perform visual inspection of fuses and relays for the fuel/fuel-cut circuit; replace any suspect parts.
Inspect wiring and connectors at the fuel cut solenoid/valve and ECM; repair damaged insulation, pins, or corroded terminals.
Measure supply voltage to the solenoid/valve with ignition ON; verify battery voltage is present at the supply terminal.
Measure solenoid coil resistance (with connector disconnected) and compare to service manual specification; replace solenoid if open or out of range.
Back-probe the control/driver wire at the solenoid while commanding fuel cut (or during conditions that trigger it) and observe with a multimeter/oscilloscope for expected switching or PWM; check for short to power/ground.
Verify ECM power and ground circuits and check for intermittent opens using a wiring diagram; repair as needed.
If wiring, supply and solenoid check good but fault persists, test ECM driver output per service manual; consider ECM repair or replacement only after all wiring and components are proven good.
After repairs, clear codes and road-test to confirm the fault does not reoccur.

⚠️ Status

ECM detected malfunction in fuel cut control circuit — fuel cut valve/driver circuit out of specification; MIL illuminated.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

Your experience will help others

+100 karma for a short comment :)

Was this AI description helpful?

Your feedback helps improve AI descriptions.

👍 Like 0 👎 Dislike 0

Send to email

P1660 — Fuel cut control circuit malfunction