Fuel Delivery Control Module Message Missing
The Fuel Delivery Control Module (FDCM) has not received a message from the fuel rail pressure sensor.
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What it means (plain English)
The computer expects to receive data from the fuel rail pressure sensor to adjust fuel delivery, but it's not getting the signal it needs, which can affect engine performance.
What the computer is actually seeing
The FDCM looks for a signal from the fuel rail pressure sensor, typically around 0-5 volts. If the voltage is below 0.1V (indicating a failure to send data), the SPN 3690 code is triggered and logged.
What a healthy reading looks like
Fuel rail pressure signals should be within 0.5 to 4.5 volts, corresponding to pressures of 50 to 400 kPa (7-58 psi).
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. Check the wiring and connectors for the fuel rail pressure sensor. Look for frays, shorts, or corrosion. If damaged, repair or replace the wiring/connector. Decision Point: If wiring is intact, proceed to step 2.
- 22. Measure the voltage at the fuel rail pressure sensor connector with the engine running. Expect 0.5-4.5V. Decision Point: If voltage is absent or outside the range, replace the fuel rail pressure sensor. If voltage is within range, proceed to step 3.
- 33. Test the Fuel Delivery Control Module (FDCM) for proper function. Consult service manual for specific testing procedures. Decision Point: If FDCM fails tests, replace the module.
Common causes
- Faulty fuel rail pressure sensor
- Damaged wiring or connectors to the sensor
- Failed Fuel Delivery Control Module (FDCM)
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive long distances as it can affect fuel delivery and performance.
Will this code come back after I clear it?
If the underlying issue isn't fixed, the code is likely to return.
Why does this code pair with others like SPN 3387?
These codes indicate related issues with fuel delivery and pressures; addressing one may involve checking the others.
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