P1002

Code

Generic P — Powertrain

Fuel Volume Regulator Control Circuit/Open

Brand: Generic

Type: P — Powertrain

Views: UK: 14 EN: 26 RU: 13

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Page language: EN

Causes

Open, broken or disconnected wire in regulator control circuit
Corroded or damaged connector at the fuel volume regulator
Failed fuel volume regulator (open coil/solenoid)
Blown fuse or faulty relay providing power to regulator circuit
High resistance in supply or ground circuit
PCM output driver fault

Symptoms

MIL (check engine light) illuminated
Reduced engine power or limp-home mode
Hard starting or no-start condition
Rough idle, misfire, or stalling
Possible increased fuel consumption or poor drivability

What to check

Scan for stored and pending codes; read freeze frame and related fuel system codes
Visual inspection of wiring harness and connectors at the regulator and PCM
Check fuses and relays for the fuel/regulator circuit
Backprobe regulator connector to verify supply voltage and control signal with key on and while cranking/running
Measure regulator coil continuity and resistance against manufacturer spec
Wiggle test harness while engine/ignition is operating to reproduce fault

Signal parameters

Supply voltage at regulator: ~battery voltage with key ON (exact value per vehicle)
Control signal from PCM: either switched ground or PWM duty-cycle (varies by application)
Regulator coil resistance: specified by manufacturer (typically a few ohms to several tens of ohms)
Control waveform: steady ground or pulsed output when PCM commands fuel volume changes; frequency and duty vary by design

Diagnostic algorithm

Retrieve P1002 and any related codes. Note freeze-frame data and test drive conditions.
Perform a visual check of connectors, wiring, and harness for damage, corrosion, pins pushed out, or signs of water intrusion.
Verify fuses and relays that supply the regulator circuit. Replace any blown fuses and retest.
With the ignition ON (engine off), backprobe the regulator connector: check for battery voltage on the power terminal and good ground reference on ground terminal.
Measure the regulator coil resistance between the regulator control pin and ground. Compare to manufacturer specification; open/infinite resistance indicates a failed coil.
Start or crank engine and monitor the PCM control signal at the regulator: use a digital multimeter for basic presence or an oscilloscope/graphing scanner to observe PWM/ground switching. No control signal indicates open circuit or PCM output failure.
If supply and control wiring are good but regulator shows open coil, replace the fuel volume regulator and retest.
If regulator is good but no control signal from PCM, trace wiring back to PCM looking for opens/shorts. Repair wiring or connector faults.
If wiring and regulator are OK but command still absent, consider PCM driver fault—confirm with manufacturer diagnostic procedures before replacing PCM.
Clear codes and perform test drive to verify repair. Monitor for reappearance of fault and check for related fuel system codes.

Likely causes

Damaged/loose connector at the fuel volume regulator
Open or shorted control wire between PCM and regulator
Defective fuel volume regulator solenoid (coil open)
Blown fuse or failed fuel system relay

Fault status

⚠️ Status

PCM detected an open or interrupted control circuit for the fuel volume regulator and set DTC P1002. The MIL may be illuminated and the vehicle may enter reduced power or limp mode until the fault is corrected. The code should be confirmed by inspecting wiring, connectors, fuse/relay and testing the regulator and PCM output.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-3.0 hours