Fuel Pump Control Circuit - High Side
A problem is detected in the fuel pump control circuit.
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What it means (plain English)
The computer is getting signals that the fuel pump is either not working or has an electrical issue in the control circuit.
What the computer is actually seeing
The ECU sees a voltage reading outside the expected range from the fuel pump control circuit, usually indicating it is too high (over 5 volts) or there is a short circuit.
What a healthy reading looks like
Fuel pump control circuit should see about 2-5 volts while operating; it might spike higher under fault conditions.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connectors in the fuel pump control circuit for damage or corrosion.
- 22. Check the fuel pump's voltage supply while the engine is running; it should be between 2-5 volts. If it's over 5 volts, there’s a problem with the control circuit. Make note of any significant voltage drops.
- 33. If the voltage is normal, verify the operation of the fuel pump by applying direct battery voltage to it; if it does not run, the pump is likely faulty.
- 44. If the pump operates, test the fuel pump control module for faults or failures; inspect it for moisture or damage.
- 55. Clear the fault code and perform a road test to see if it returns.
Common causes
- Damaged wiring in the fuel pump circuit
- Faulty fuel pump control module
- Poor connections or corrosion at connectors
- Defective fuel pump
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with SPN 5104 active?
It’s not recommended; the fuel pump may fail, leading to an engine stall.
Will this code come back after clearing it?
Yes, if the underlying issue isn't resolved, the code will likely return.
How does SPN 5104 relate to fuel pump performance issues?
This code indicates a fault in the control circuit, which can affect the pump's operation, leading to poor engine performance.
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