ABS Light on? Here's How to Diagnose a Wheel Speed Sensor on Your Prado 120

Common Causes of a Continuous ABS Light

If your Toyota Land Cruiser Prado 120's ABS light stays on, the most frequent culprit is a faulty wheel speed sensor. These sensors monitor each wheel's rotation and send data to the ABS control unit. Over time, they can fail due to dirt, corrosion, or physical damage. Other possibilities include a damaged tone ring (the toothed wheel the sensor reads), frayed wiring, or a failing ABS module—but start with the sensors.

• Wheel speed sensor failure – internal break or short circuit.
• Contaminated or damaged tone ring – cracks or missing teeth can disrupt the signal.
• Wiring issues – chafed, corroded, or disconnected wires near the wheel.
• ABS module fault – less common, but possible if sensors and wiring check out.

Which Sensors to Check First

On the Prado 120, the front-left wheel speed sensor often gives trouble first because of its exposure to road debris and moisture. However, all four sensors should be inspected. Use a multimeter to measure resistance (typically 1–2 kΩ) and check for AC voltage while spinning the wheel (should be a few hundred millivolts). Visually inspect the sensor tip and tone ring for dirt or damage. If you have a scan tool, read ABS fault codes—common codes are C0200 (front-left) or C0226 (rear-left).

Is It Safe to Keep Driving?

Yes, it is generally safe to drive with the ABS light on, but with important caveats. Your standard brakes will still work normally—the system simply disables ABS, traction control, and sometimes stability control. Avoid sudden stops or slippery roads, as you won't have anti-lock assistance. Drive cautiously to your mechanic or home, and get the sensor diagnosed soon. A faulty sensor can also trigger the brake warning light if the system detects a critical issue, so pay attention to any additional warnings.

This material is AI-generated and for informational purposes only — it does not replace an in-person diagnosis by a qualified mechanic.