A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
OOleg’s tip: it’s not always the sensor
It may not be the sensor itself but what it reads the signal from: the tone ring on the hub or axle shaft, or, on many cars, a magnetic ring that is built into the wheel bearing itself. Dirt, rust, a crack or damaged teeth, or bearing play — and there’s no signal even though the sensor is fine.
Remove the sensor and, turning the wheel slowly, look at the tone ring: are all the teeth intact and clean? Rock the wheel by hand — bearing play also disrupts the signal. The magnetic ring isn’t replaced separately: it’s part of the bearing.
Possible causes
- This wheel’s speed sensor
- The sensor connector: dirt, water, corroded pins
- The sensor wire is chafed or broken — in the wheel arch, by the shock absorber or at the bend near the hub
- The tone ring or the bearing’s magnetic ring: a crack, dirt, stuck-on metal shavings, bearing play
- The sensor isn’t seated properly: too big a gap to the ring, or rust under the sensor
What you can do yourself
- With this fault ABS usually switches off: the ordinary brakes still work, but without ABS the wheels can lock. Brake smoothly and leave a bigger gap, especially on slippery roads.
- Inspect this wheel’s sensor and its wire up to the connector: dirt, corroded pins, chafed insulation. Clean the connector, remove the sensor and clean its tip and its seat of dirt and rust.
- Check the tone ring or the bearing’s magnetic ring: cracks, damaged teeth, stuck-on metal shavings. Don’t clean a magnetic ring with a magnet.
- A scan tool’s live data shows each wheel’s speed: while driving, this wheel should read the same as the others.
Stop and don’t drive on if:
- The red brake light is on, or the brake pedal feels soft or sinks
- The steering became very heavy, or the car pulls to one side when braking
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
Find the part on Kaspi ShopBefore buying, check the part number or match the part by VIN in the Kaspi “Garage”.
On cars with flash-code self-diagnosis the ABS light shows this code as 31. This is the Toyota and Lexus meaning. On other makes this number means something else: if your car isn’t a Toyota or Lexus, change the make at the top.
Source: Toyota 4Runner 1996–2002 repair manual (ether3al.com)
The explanation comes from the error code reference in the AvtoElektrik PRO app.