"H. P. Friedrichs" wrote:

I had a mid-90's Chevy S-10 with antilock brakes. One day, the brakes
made a funny sound and the service light came on. I noticed that the
brakes were not behaving properly.

I took the truck in for "Mr. Goodwrench" to take a look. They told me
that I would need a new antilock computer and the cost was something on
the order of $1000. I told them to forget it.

I limped the truck home and later, curiosity got the better of me. I
jacked up the truck so that the front wheels could spin, and then I went
hunting for wheel rotation sensors. Connecting my scope, I could see a
nice, clean sine wave coming off the front right wheel. The waveform
from the front left wheel, however, had a a very irregular shape that
was much lower in amplitude.

I purchased a new rotation sensor for $75 bucks, pulled the wheel and
brake disk, and installed it. Everything worked like a champ after that.

It appeared that the old sensor had been struck by rock, and the core of
the sense coil had probably been fractured. I was left to wonder how it
is that, without the benefit of factory training, documentation, or
diagnostic equipment I could troubleshoot and repair the problem when
the dealership could not....

Michael A. Terrell wrote:


That is why for the few things on my truck that I don't have the
facilities to do myself and can't justify buying new tools, when I take
it to the dealer for service I give them a specific set of instructions
on what to do and clear warning that they are *not* to attempt any
diagnosis or deviate from the exact work order I give them.

Pete C.