FC 2266 — Electric Lift Pump Circuit – Voltage Below Normal (SPN 1075 FMI 4) — Cummins ISX15
Diagnostic reference for Cummins ISX15 (2010–2017) FC 2266.
What it means
FC 2266 is SPN 1075 FMI 4 on Cummins ISX15. Generic definition: the electric lift pump circuit voltage is below normal or shorted. Typical on this platform: a shorted lift pump circuit or failed lift pump.1
Most likely causes
- Shorted or chafed wiring to the electric lift pump causing low circuit voltage — Inspect the lift pump power and ground circuits for shorts to ground, chafing, or damaged insulation that pulls voltage down. Look for melted loom, rubbed harness near frame/rails, and corrosion at connectors.1
- Failed electric lift pump drawing excessive current or internally shorted — A failing pump can present as low voltage on the control circuit. Check pump current draw and listen for abnormal noise; compare to known-good behavior.1
- Corroded or loose lift pump connector causing high resistance and low voltage at the pump — Examine the lift pump connector for moisture, corrosion, bent pins, or loose terminals that increase resistance and drop voltage.1
How to diagnose
- Verify FC 2266 is active and note freeze-frame conditions (key-on/engine-off vs running).
- Inspect the electric lift pump harness and connectors for chafing, shorts to ground, corrosion, or loose terminals; repair wiring faults before replacing parts.
- Check supply voltage and circuit integrity at the lift pump connector with key on; look for voltage below normal indicating a short or excessive load.
- If wiring is intact, evaluate lift pump operation and current draw; abnormal draw suggests pump failure.
- Clear codes after repairs and confirm FC 2266 does not return under normal operation.
Parts and tools you may need
- Digital multimeter
- Wiring diagram for ISX15 lift pump circuit
- Dielectric grease
- Replacement lift pump (if testing confirms failure)
- Basic hand tools for harness access
Tools you’ll need
- digital multimeter — Measures supply voltage at the lift pump connector to confirm low voltage or shorted circuit condition.
- wiring repair kit — Repairs chafed or corroded lift pump harness and connectors that cause low circuit voltage.
- clamp meter — Checks lift pump current draw to identify excessive load or internal short indicating pump failure.
- inspection light — Illuminates harness routing and connector terminals for chafing, corrosion, or loose pins.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| Wiring or connector repair | $10–$100 | 1–4 hrs | DIY with tools and a manual |
| Lift pump / fuel transfer pump | $100–$400 | 1–3 hrs | DIY with tools and a manual |
Typical US independent-shop figures; labor runs about $140–$200 per hour (dealers charge more). Confirm the diagnosis before buying parts.
When to see a pro
If voltage remains low after visual inspection, or if high-pressure fuel system work is required, have a certified Cummins technician diagnose with Insite to avoid misdiagnosis and unsafe fuel system handling.
Check for recalls
Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.
Sources
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