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.
Speed Sensor
Rod-shaped speed sensors (impulse transmitters) measure wheel speeds. Three speed sensors measure wheel speed of each front wheel and both rear wheels. Speed sensors for front axle are on steering knuckles. Speed sensor for rear axle is on axle housing. Drive pinion serves to measure rear wheel speed.
Speed sensor measures wheel speed by sensing rotor teeth movement. On front axle, rotor teeth are machined into front wheel hub. See Fig 1.
On rear axle, toothed rotor is pressed on drive pinion. Axles with different ratios have gear wheels with different number of teeth. Speed sensors consist of magnetic core and coil. Rotation of rotor, set specific distance from sensor, causes alternating voltage in coil.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.