RF wheel lock, ABS sensors and codes

[whitechalk]

2002 Explorer XLT 4dr, 90k miles

We had a RF wheel lock identified (by Michelin) from scallop in Uniroyal Laredo tire from this vehicle, and are now trying to figure out why the wheel locked. Two questions:

1. Visual inspections of RF brake system (pads, calipers, disc, hydraulic line, electric wire) and suspension components show no obvious signs of locking. Still want to look closer at hydraulic lines for signs of crimping or obstruction in return lines. Failing that, what else could cause a single, front wheel lock sufficient to scallop the tire? Where can we look in the vehicle to confirm cause of the lock we observed from the tire? Is it possible that wheel locked and then "unlocked" at some point, so that there is (now) no physical sign of why it locked initially?

2. ABS light is "on" on dash, but ABS scan by Ford failed (all other systems passed scan), though we still hope to rewire to identify power or ground issues and scan again. . . We think ABS would record at least the trouble code generating the ABS light, but would also record info from RF wheel sensor indicating that lock occurred, possibly as part of continuous monitoring if not as trouble code. Ford says a lock from one wheel sensor is not a "fault" in an ABS system, it's part of normal operations, and so would not be recorded anyway. We may find out, if we can get the ABS to scan, but does anyone know who is right on this? Are there additional codes we should be sure the scanner is programmed to detect?

Any other ideas/comments? We're stuck and welcome any input.

[theoldwizard]

While I would still follow up in the ABS light, I don't think it the "root cause" of you tire scallop. That is usually caused by worn suspension parts; ball joints and/or shocks.

[whitechalk]

Just fyi, the scallop was not a long-term, slowly-developing thing, it was sudden and caused complete loss of control of the vehicle. That's why Michelin says it was a wheel lock, so not something related to worn parts. Any ideas about what might cause a sudden wheel lock like this in just one wheel? Where should we look?

[cjones]

was it just one scallop?? i someone locks up the brakes for a long time you could get a flatspot. if so, get the ABS connection working and go from there

have you checked all the ABS fuses??

if they are many scallops evenly spaced around the tire then i would agree with theoldwizard about checking the suspension.

[darkwolf1469]

i have a 92 ford aerostar xlt w/ electronic 4-wheel drive. what would cause the front wheels to seem as if they are grabbing as i drive down the road. when they grab, i press on the brake pedal and the grabbing stops temporarily. brake pads are disc with alot of life left on them