Note: Some vehicles use two separate sensors with one being on the front differential, and the other on the rear differential. 

Once you remove the sensor you should see the two contacts where the plug connects. Clean off any dirt or grime that may have built up in there.

Now put one lead on each contact while your meter is in the Ohms setting. This particular sensor is 50 Ohms, so I should read 50 Ohms across the two contacts. Check your service manual for your vehicle's specific value.

If your meter doesn't move or shows an open, then your sensor is bad. If the reading is a lot higher than it should be, you have high resistance on the coil, and the sensor will need replaced. Similarly, if the reading is of very low or zero Ohms, then you have a shorted coil. Most ABS wheel sensors can be purchased from a local dealer for well under $100 U.S.

A few tricks to try if the sensor is good, but you still have an ABS problem.

A very dirty sensor (the part that sticks into the differential), can cause an incorrect output to the car's computer, causing an ABS light. Simply clean off with some cleaner and a rag.

Even if the sensor reads good, you may have a break or short in the wiring to the sensor. Most likely it will be near the sensor because this is the dirtiest area in the circuit. If no damage is found there, follow the harness up to the engine or dash connection. 

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