After a major maintenance day (all four ball joints, and both CVs) and as soon as I started the truck to go for the test drive I notice that the ABS light is on. After the drive, I removed the tires to make sure everything is connected and sure enough everything is good. I notice some movement at 3 and 9 oclock so I am assuming the wheel bearing is shot, could the bearing being bad be throwing a bad signal if the ABS wire got messed up on it somehow in all the maintenance today? After moving the ABS wire from the bearing around the light went away for a little bit then it came back on. Any thoughts?

 

Sometimes the wires go bad, actually break inside the insulation. The only way to fix it is have someone hook up a scanner to determine which one is giving the signal then replace the end of the wire harness that plugs into the sensor...usually about 4-5 inches.

 

You can check the sensors yourself with a multimeter set to the mV-AC setting. Disconnect the WSS (wheel speed sensor) and connect the multimeter to the two leads in the connector to the sensor. Spin the wheel. The mV-AC output should be around 300mV for a properly working WSS. Check both.

If it is below 250mV-AC, then you havea sensor problem that could be due to excessive air gap between the sensor and the reluctor ring inside the hub. This can be cured by filing down the surface that the sensor mounts to on the hub assembly. This will tighten the air gap, increasing the output of the sensor.