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.
Code 31, Engine Speed Governor - 5.7L "G" Series: Notes
The PCM controls the engine speed control governor based upon engine speed (RPM). The PCM sends a pulse width modulation signal to the engine speed control governor module to drive the engine speed control governor motor. Depending upon the amount of governing required, the module translates the PCM data into a voltage signal which it sends to the motor. The motor then pulls back the throttle to the correct overspeed condition.
A Code 31 will set if a fault occurs in the governor module, motor, linkage, wiring or PCM. If Code 31 is set, the PCM will limit engine speed by momentarily reducing fuel delivery to injectors.
- Determines if engine speed governor module has proper voltage.
- Applying voltage to the motor will determine motor, wiring and linkage integrity. DO NOT hold current to motor for longer than 30 seconds or damage to motor will result.
- This will command full governing to determine if PCM or engine speed governor is at fault.
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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.