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 P0502: Vehicle Speed Sensor Circuit - Low Output: Description
Vehicle Speed Sensor (VSS) system is a pulse generator consisting of a speed sensor assembly, located in case extension, and a toothed vehicle speed sensor reluctor wheel, which is pressed onto final drive carrier assembly. As vehicle drives forward, vehicle speed sensor reluctor wheel rotates. This rotation produces a variable AC signal in pick-up coil that is proportional to vehicle speed. PCM uses this signal to calculate vehicle speed, shift timing and gear ratios. This information is then sent to the PCM to indicate how fast the vehicle is traveling and to develop the shift pattern for the transmission. Other systems also use VSS information:
- TCC apply and release.
- Cruise control system.
- Fuel delivery systems.
DTC sets when PCM detects a low vehicle speed with a high engine speed while in a drive range.
NO RELATED
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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.