Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit Description
Fuel pump operating speed is controlled by operating condition of the engine such as: starting, idling, light load or heavy load. When engine is cranking and start signal is received at ECM, the ECM energizes circuit opening relay and voltage is applied to both sides of fuel pump relay. Fuel pump relay contacts are closed on one side and voltage is applied directly to fuel pump in which fuel pump operates at high speed. After engine starts during idling or light loads, fuel pump relay is energized by FPR terminal of ECM and contacts in fuel pump relay close to other side of relay. Voltage is then supplied to fuel pump by going from fuel pump relay through fuel pump resistor. Fuel pump now operates at low speed. DTC is set when ECM detects an open or short in a fuel pump relay circuit. Possible causes are:
- Fuel pump relay circuit is open or shorted.
- Defective fuel pump relay.
- Defective ECM.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.