I know I have replied to many posts where the OP stated they already replaced the VSS but still have the same issue. Yes, they do go bad but before spending the bucks on one it is easier on the wallet to look at the other more common causes.
I think subford holds the record for most "assists" with this issue!
It is almost imposable for a VSS to go bad unless you break it while removing it or it is hit by something in the rear end.
Sometimes it has been installed wrong with too large a gap or has something build up on it as it is a magnet.
Not sure how it would loose it magnetism but that may be possible somehow.
If someone or some part in the PSOM or RABS puts power to the VSS wires that could burn open the coil in the VSS. The VSS supplies its own power.
The VSS just consists of a permanent magnet, a ferromagnetic pole piece, a pickup coil, and a rotating toothed wheel. No moving parts in the VSS.
As the tone wheel teeth of the rotating tone wheel pass by the face of the magnet, the amount of magnetic flux passing through the magnet and consequently the coil varies. When the tone wheel tooth is close to the sensor, the flux is at a maximum. When the tooth is further away, the flux drops off. The moving target results in a time-varying flux that induces a proportional voltage in the coil. Subsequent electronics (PSOM & RABS module) are then used to process this signal. The PSOM then drives the Speedometer, updates the mileage in the LCD odometer display and the EEPROM and sends a digital waveform to the Speed Control and the PCM Computer..
it doesn't make any sense because that's not a ware item.if the 50 replacements cured the shifting issues,then more than likely simply cleaning the sensors,rather than replacement would have done the same thing.it's actually pretty easy to know when one is in need of cleaning,as the speedometer needle will be bouncing.once it gets so bad,it will start to frig up the trans operation because the control unit can't read the speed accurately.
however i can easily see how a steelership wouldn't bother with such things.they would want to simply change the sensor so they could charge for the part and the labor to replace it.they didn't get their derogatory nickname for nothing.