One from the X-files.

[Jeremy airjer W]

It's not to often I get stumped but the other day I had to admit defeat.

A few days a ago another tech did some brakes and a couple tires on a 2004 (I think) Dodge Dakota. It came back shortly after the repairs where made with the ABS light on. A quick scan revealed the right front sensor was not giving any signal. Check continuity at the ABS module 1k ohms, same is the other side. Check A/C voltage .040 volts max. The other side showed .3 to .4 volts A/C. We determined that something was wrong with the speed sensor and attempted to replace it first.

New speed sensor installed, everything put back together and no signal. Double check everything. Decide to replace the bearing thinking there is an air gad issue with the exciter ring. Plug the bearing in and check the signal on the scan tool before install and it looks great as we spin it by hand. New bearing installed everything put back together, no signal.

Double check everything with the same results. Decide we received a defective bearing but my spidey senses are starting to tingle. New bearing shows up and we decide to test it out of the box. 1k ohms of resistance, .3 - .4 volts a/c when spun by hand, checks out good.. Next we decide to systematically check the data as we go through the install process. Install the bearing to the hub and double check the data, everything o.k.. Plug the harness into the body connector, double check the data, it's good. Plug the body connector into the ABS module check the scan tool for signal. Looks good. Install the tire, check the scan tool signal, no signal.

Aha, at this point I make my case. I think it's the tire. Call the service manager over and there is disbelief at my hypothesis. So I decide decide to do a little experiment with everyone present. I spun the left side by hand while we watched the scan tool data. I could get 10+ mph with a clean consistent signal. Swapped the two front tires. And guess what, NO SIGNAL.

[Scott K]

The wheel magnetized?

I just ran into a magnetized tooth on a transmission oss sensor. Just one tooth of the exciter ring would drop out on the scope, pulled the tranny down, no physical damage. Reassemble, still missing signal from one tooth. Tear it back down, grabbed a screw driver and one tooth was magnetized.

[Jeremy airjer W]

Aluminum wheels.

I had an old ford escort that the cam was magnetized. The shaft in the distributors on those old ones would magnetize fairly frequently. Nothing you can do when the whole cam is magnetized.