Oldsmobile/Buick Repair: Diagnosing ABS, wheel abs, drive shaft

Question
Is ther one at every wheel? I dont recall seeing any wires at the rear when we were under there.-------------------------
Followup To
Question -
1991 Olds Custom cruiser(GM B body full size rwd wagon). 305 V8 AT. Brake fluid fine. Rear high lite is working. ABS lite comes on & stays on shortly after starting driving. I am guessing a wheel sensor but i can't be sure. &  if so how do i figure out which. Is there a method?
Answer -
hi bill.. yes you are prob right normally is a wheel sensor.and without a computer it is pretty difficult to figure out.but here is something you can try.the bad sensor will have the highest amount of resistance .take a voltage tester with an ohms meter on it.at each wheel unplug sensor test resistance at sensor end record ohms reading check all abs sensors the one that has the highest reading will be bad.assumeing the sensor is the prob.good luck bill.please take a minute to rate my service it is very important to me ty billymac

Answer
hi bill well it really depends on if you have 4 wheel abs or rabs.which is just rear wheel.if you only have rear wheel abs the sensor in your car will actually be in the rear axle near the drive shaft.it will be bolted into the houseing.if you have sensors at the front wheels you have 4 wheel abs.good luck