abs problem

[olimaxx]

i bought an Innova 3160 scan tool. works goosd so far. I have an abs light on. cant pin point. scanner says right front tone problem. code P0035. i ohmed out sensor, on 2k scale it reads 1.26 the left reads 1.36. my work truck reads rt 1.56 lt 1.76? any suggestions. i have pulled off the calper and pulled sensor , no corrision or rust....please advise.

[olimaxx]

update. its code c0035 and one for the output speed sensor. changed the output sensor. swapped right abs still reads " tone " right wheel. please help. ps. abs works fine but wanna get rid of light.

[olimaxx]

are they different for differ vehicles?

[DmaxMaverick]

The design of the sensors is the same, within respective model years, but the bearings can be different among models. The sensors (the part that inserts into the bearing) can be interchanged among most models within model years (or a span of them). Most often, the sensor and tone ring become fouled with corrosion or other contaminants (road salt, etc.). There is a recall and TSB on this for certain model years and climate regions (salt belt), but it can happen in other areas for different reasons.

If the problem is in the wheel end, the entire bearing may have to be replaced. In the past, not much success has been had with switching only the sensors. I have a couple sensors taken off replaced bearings (no sensor problems) I have sent to other TDP members and offline friends for troubleshooting purposes, with problems similar to yours. In every case, the bearing needed replacement in the end and the problem was cured.

However, consistent speed sensor errors could just as likely be wire/connector related. Dirty or corroded connectors can be a real pain to identify. The operating range of the sensors is actually very wide, but the ABS controller is more sensitive to the variation of the wheel speed pulse changes (as wheel speed changes). Resistance values are of little value, and can swing greatly, even under ideal conditions (one of the first things I tested with the first complaints of this type). Most of the time, it didn't matter at all, and none of the vehicles were the same, and none of the wheels on the same vehicle read the same (like you are seeing). Old news, in my book, and I don't even look at this value any more.

[olimaxx]

thanks for the reply. i checked the hub. cant feel any slop in it. what would cause the failure? what size is the axle nut? might change my self.

[DmaxMaverick]

The axle nut is 36mm. Torque a NEW axle nut to 155 ft/lb. The hub to knuckle bolts torque at 133 ft/lb. The wheel speed sensor bolt is 13 ft/lb. The caliper bracket bolt is 221 ft/lb.

[olimaxx]

what would cause the hub to not read anymore. there is no slop in the bearing?

[DmaxMaverick]

Hard to say. It is a mechanical to electronic interface, so anything can happen, at any time. These things are really much more forgiving than we deserve. My first bearing failure was obvious, with plenty of wiggle that no rocket science was needed to see it. The second, not so. The play was well within spec (barely noticeable, if at all), but it still had a slight growl under load (towing) at low-mid highway speed. Within 10K miles, the play was as obvious as the first. I kept a close eye on it, and it seemed to "let go" overnight. The "squeaky wheel" did get the grease, eventually. The good thing about these, even when they are in so bad shape they seem to be no better than old skate wheels, they hang on (as in: no catastrophic failure). In every case I've seen, they complain well ahead of any serious failure. In any case, these things, as with all man-made devices, can fail for any number of reasons, or none at all, at any time. They are still manufactured by human hands, after the engineer decided his idea is better than anyone else's (sometimes, they get one right).

How are you testing the bearing play? If you are doing it by just wiggling the bearing, that's not good enough. Most often (early on), it takes significant leverage to actually see any play. Do it with the wheel on, jack the wheel off the ground and push/pull on the top of the tire. Check at several clock positions of the wheel. Any more play than the slightest noticeable, is a bearing on the way out.

[rat4go]

I think the service bulletin suggested that in areas that use salt, the hub can corrode under the speed sensor causing the gap between the sensor and the tone wheel to be too far apart to get an accurate reading. Since your sensor checks out OK, you might want clean up the area around the sensor hole to try to get it flat and to not have any rust that would prevent the sensor from going far enough into the hole on the hub. Make sure you plug the sensor hole to keep crap out before you start filing, grinding, etc.

Hubs aren't too hard to replace, but they're pricey. Local NAPA had 'em for $235 each (including the sensor).

Good luck!

[olimaxx]

well thanks everyone.... what a pain. it turns out i did the wiggle test and the hub is bad. gettin new tomorrow. remind not to lift my next duramaxx. it looks good but it cost money.