I recently bought a used 97 4x4 ext. cab. I replaced lower ball joints and one front 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 hurt 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 every time? (i.e. I don't have to disconnect battery or take any action)

 

now you say you replaced the bearing, you mean hub assembly correct? also did you get aftermarket hub? the speed sensor picks up it signal from the bearing. that may be your problem

 

Yes, I replaced the hub assy. It has a speed sensor with it, but I re-used old one rather than mess with the wiring (I had it unbolted already off the old hub assy.

 

Update, I cleaned the connections at the front sensors and measured their resistance..both were ~500 ohms, so I am pretyt sure I ddin't damage wiring. Any thoughts ?

 

the only other thing i can think of would be the hub needed the sensor that you removed from it. excessive air gap can cause a trouble code to be set. the new sensor you removed might need to be installed. before you do that, disconect your battery to clear any codes. then when you hook it back up notice whether or not the abs light is on or if it goes off. usually if the system has a electrical open circuit the light will come on because the system does a self check evertime you switch the truck on, and with an open circuit it will fail. now if you drive your truck and the light comes on you have a sensor read error, which could be this new hub you replaced.

 

I will try to replace the sensor in the new hub with the sensor that came with it. The light stays off until the truck moved about 100 yards, simply starting the truck light stays off. I was under the impression the ABS error codes did not have to re-set with battery disconnect. Perhaps I have fixed it and the code never got cleared.

 

you dont have to disconnect the battery, it was just an easy way to work in my explanation. if you have to move the truck to mkae the light come on you have a sensor coherency problem, which if you did not have the problem before, then i say it is the one you replaced. replace the sensor with the new one a see what happens

 

The light stays out until the truck moves ~100ft. No other light (brake) are on. I will try to swap out sensor, but since old one has same ohms reading I am not holding my breath.

 

I would remove the sensor and carefully check in the hole to make sure the tone ring is there and not cracked or anything.

 

I removed both sensors and cleaned them right after I had the issue. The hole thru to the sensor ring l(and ring) ooked fine. How easily is the sensor ring damaged? Other than getting foreign debris in there when I removed the sensor I am not sure what could be wrong.