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.
DTC 31: Engine Speed Governor - "G" Series: Notes
Control module controls engine speed control governor based upon engine speed (RPM). Control module sends a pulse width modulation signal to engine speed control governor module to drive engine speed control governor motor. Depending upon amount of governing required, module translates control module data into a voltage signal which it sends to motor. Motor then pulls back throttle to correct overspeed condition. A Code 31 will set if a fault occurs in governor module, motor, linkage, wiring or control module. If Code 31 is set, control module will limit engine speed by momentarily reducing fuel delivery to injectors.
- Determines if engine speed governor module has proper voltage.
- Applying voltage to 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 control module 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.
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