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 24 - Output Speed Sensor Low (4WD): Notes
The speed sensor, which is a Permanent Magnet (PM) generator, provides PCM/TCM with vehicle speed information. PM generator, mounted in transfer case, produces a pulsing voltage signal whenever vehicle speed is more than 3 MPH. Control module uses this signal in calculations to determine vehicle adjustments.
Code 24 will set under following conditions: vehicle speed is less than 20 MPH, transmission is not in Park or Neutral, and engine speed is more than 3000 RPM. All of these conditions must be met for 1.5 seconds. PM generator only produces voltage signal if drive wheels are turning faster than 3 MPH.
- This step tests for voltage variation while wheels are turning. Voltage will be low at low wheel speeds (4-6 volts at 20 MPH).
- This step tests operation of output sensor.
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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.