I recently bought a used 97 4x4 ext. cab. I replaced lower ball joints and one wheel bearing this weekend and I have the ABS light since. I have 4 wheel ABS and the new bearing assy had a sensor, I removed and re-used old one one rather than unplugging it from harness. I thought maybe I got grease/dirt on the abs sensor on one of the sensors, but took the sensors back off tonight and cleaned them...same issue. I did collapse the calipers slightly to ease the caliper re-install, could I done anything then? I hear the 4 wheel ABS need the codes pulled at dealer. :-( Any thoughts? I did a search and I think I can test the ohms resistance of the sensors. Maybe I gurt a wiring harness? Anyone know off the top of their heads what they should read. And is it true that the codes get automatically reset evey time? (i.e. I don't have to disconnect battery or take any action)

 

Update, I cleaned the connections at the front sensors and measured their resistance..both were ~500 ohms. Any thoughts ?

 

Hello,

I have the same problem. Did you ever find a solution?

 

Use the new sensor that came with the new hub. The clearances may be off from one to the other, and the old sensor may not be picking up the new tone ring.

-Joe

 

Well, I have a reversed situation - new sensor, old hub. No problems before the new sensor, now I get the light. My fronts read about 440ohms, the rear is 1800ohms... all in spec. I am going to try and measure the AC voltage while spinning the front tires to see if I can get a reading and eliminate one sensor or the other. I read on here that the at 1 tire revolution per second, the sensor should produce 1-2v (AC). We'll see what happens. I just spend $160 on that darn sensor so I hope I dont mess anything up.

 

It ended up the brand new hub and sensor has grease packed in the teeth of the hall effect sensor where the sensor read the speed of the hub. I cleaned all the grease out of the teeth and worked fine. That's what I get for buying cheapie parts at Discount Autoparts. (it was late and Napa was closed)

 

When i took the old sensor out, it broke from forcing it out. When I put the new one in, I lube'd it with grease so it didnt get stuck, like the old one. After the new one didnt work and caused my light to go on, I ended up taking it apart and removing the grease. I also noticed that when I put the allen screw back in, there must have been some rust dust that fell into the screw hole so the screw felt tight, but it wasnt holding the sensor tight. I put a small lock washer under the head of the allen screw and reassembled. That worked! For those of you who are having problems this is what I have found... the front sensors should read 400-500 ohms, the rear should read around 1800 ohms (i have read other people say 1500 - 3000). As I discovered, just because the sensors are bad, does not mean you have to have the truck scanned... check and make sure the connections are good and the sensors dont have any metal filings or too much grease on them. Also, if the light doesnt come on until you drive a few hundred feet, it is most likely a sensor read issue. If the light comes on right away, then there's something broken somewhere. Thank you everyone on this site who contributed to my quick ABS lesson.