Yo R,
Welcome!
For the sensor mounted on rear differential..
It is often known as;
Applications, Bronco, "...Pre~85 used a cable-mounted VSS (6 pulses per cable rev) for cruise only; ~85-91 used a t-case mounted VSS (6 pulses per cable rev) for cruise and E4OD shifting. The rear differential mounted VSS, aka ABS sensor was only used for RABS. The ESOF t-case always had its own dedicated speed sensor.
92-96 use the ABS sensor (108 pulses per diff rev) in the rear axle (via the ABS module) to feed the PSOM, which then feeds everything else..."
"it's best to have a wire brush and screwdriver to loosen any dirt mud gunk around sensor so it doesn't contaminate the oil when you remove it. It also helps to have compressed air as I did but not necessary. Clean as good as possible then remove the bolt and wire harness and gently pry with flat head enough to lift past the o-ring being careful not to push screwdriver to far in and damage o-ring.
Next pull sensor out of hole and examine. if it is dirty,then it needs cleaned off. (this could cause an RABS light on the dash to illuminate) I used throttle body cleaner then dried with rag lubed o ring with silicone (any grease or oil should do) this keeps the o-ring from cracking and makes install easier." by slickerthanyou
"87-up ABS sensor bolt is like the rear cover bolts: 13mm hex head @ 25-30 lb-ft. 800-1400 Ohms across the pins, and more than 10K Ohms from the metal shell to either pin. If any VSS problem is suspected, pull the ABS out & look for damage, indicating a serious problem in the diff.
Notice the small metal tooth-that is what picks up the speed signal. It is a magnet.
Now just push it back into hole and tighten bolt (snuggly). Attach the harness and your done- go grab a cold one!" by Steve
Removal/Installation (rear diff); ",,,1 bolt holds it. clean around the area first so crap does't fall into your diff housing through the hole. be careful with it, the sensor housing is just plastic, and the magnet inside has wires that run to it. basically once you pull it, you will see it has a little rubber o ring for sealing (and it fits snugly, so if you've never removed it, it might feel like it does not want to come out at first). You can look down into your diff and see that it sits just right on top of a "toner" ring which turns with the carrier. The magnet at the tip is very close to this toothed ring, and the interuption of the magnetic field by the teeth as they pass close to the magnet creates a variable signal, which can be "interpreted" into a speed reference for the computer, tranny, etc..." by shadowfax
One more for posterity;
Removal/Installation (rear diff) Article & Depiction
Source: by Chilton via Waltman at
http://web.archive.org/web/20131008181435/http://www.supermotors.org/getfile/257981/fullsize/rabs.jpg
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