Dana 80 sensor?

Vehicle Speed Sensor. It picks up a signal from a tone ring on the ring gear. Also used by ABS system.

So it does both abs and vehicle speed?

Correct. It would compare the speed of the individual front wheels with the rear axle speed to tell if one is slipping. My truck has just RABS, with just the VSS on the axle. It must use some kind of magic to sense when the rear wheels start to skid.

The 6.0L also has ABS sensors at each wheel. The rear differential provides vehicle speed, and does offer some redundancy in the ABS management system (as stated above). That said, primary ABS function though is from the ABS sensors at the wheels (at least how I understand it).

bismic said:

The 6.0L also has ABS sensors at each wheel. The rear differential provides vehicle speed, and does offer some redundancy in the ABS management system (as stated above). That said, primary ABS function though is from the ABS sensors at the front wheels.

Click to expand...

Are you sure there are sensors on each wheel (I haven't physically seen them on a 6.0L)? The wiring diagram for 03 just shows the differential sensor and the front wheels. It doesn't differentiate between the 7.3L and 6.0L engines.
Like I said, with RABS on my '99 the ABS module must use some sort of black magic to tell when to activate with just the differential sensor.

That black magic is calculus. The computer integrates the vehicle speed and if it sees too large of a deceleration it assumes that the wheels have locked and needs to activate the ABS. It isn't possible for the vehicle to actually stop from 40 MPH in one second, unless it's run into a brick wall, and then the ABS doesn't matter.

Thanks, Mark.
Agree that ABS won't help hitting a brick wall.

In the Owners Guide also (page 130):

No argument that there are individual sensor on the front wheels, but I thought you were talking about wheel sensors on the rear as well, when you said

bismic said:

ABS sensors at each wheel.

Click to expand...

Ford does call it 4 wheel ABS, but there are only 3 sensors.

Ah, OK. I missed that part of your post (sadly you were clear enough ). I originally did put "front sensors", in part of my response, but then mistakenly called it "all 4". My apologies.