Heads up, trying to clean or replace one of the front ABS sensors on a 4WD might end up causing the replacement of the wheel hub.

[sehaare]

1998 SOHC xlt 4WD Rust bucket.

I had an issue with the ABS kicking in just before the SUV came to a stop but no ABS warning light. It would pull to the right and after looking at the brakes, the front Right pads were almost completely worn away while the drivers side had a lot of life left in them.

Before going after the ABS issue I went ahead and did a complete brake job on both axles pads, as it was due, pads, rotors and calipers up front, and pad and rotors in the rear. As I expected, after the brake job the SUV braked perfectly when the ABS fuse pulled, but still had the same pulling issue when the ABS fuse was put back in. So my next step was going to be to pull the driver side front ABS sensor to take a look at it and then initially try cleaning it before replacing it if necessary. Everything up to removing the sensor went pretty quick since I had just removed everything for the brake job a few days before.

When it came to removing the sensor, I made sure to clean out the Allen head bolt that holds the sensor in, so that I didn't strip it out. The bolt came out pretty easy by using just an Allen wrench (no need for an Allen socket). The sensor was in there tight so I started to wiggle it out and finally it came out - or so I thought until I looked at it. The sensor had come apart. What came out was the guts of the sensor with the copper coil wiring exposed. The case that the guts went into, stayed stuck in the wheel hub. No way to get that out without trying to pick it out and probably having broke pieces and rust fall into the hub.

So at this point I have a Motorcraft Wheel hub on order from Amazon. I was surprised to find that none of the local Autoparts store carried the Axle/spindle nut and I had to order that from Rock Auto. I would have just gotten the nut from Ford but I remember from when I replaced the front axle that Ford charged me $25 for that nut and checking this time on rock auto it was under $8 including shipping.

On the positive side, I guess that fact that the sensor fell apart is a good indication that it was the bad one.


So, if you are thinking about replacing the ABS sensor you might be opening up a can of worms like I did.

 

[J_C]

Same thing happened to my sensor when I removed it, except I was able to pull the pieces out of the hub. I got a 2 pack of generic sensors on Amazon for around $18 (bought before I removed the sensor, anticipating I might need them and not wanting the vehicle sitting taken apart), but then decided it was time to replace the hub anyway as the sensor itself wasn't bad until I pulled it out (and still read the correct ~420ohms resistance even with the outer casing broken off) and if dirty grease is getting flung around, wiping the sensor off doesn't get the grease any cleaner, would only be a temporary solution.

That fixed the ABS issue but now a couple years later, my other (still factory original) front hub is causing ABS to activate again... time to replace the other hub. I got the Timken hub from Rock Auto last time, and reused the nut. Not sure what this "service design" Motorcraft part is on Rock Auto now in their economy listings, at $107 it's a lot cheaper than I saw the Motorcraft hubs for back when I got the Timken. What little I could find, suggests that these "Service Design" parts are lower quality. I'm aware my 2nd link below is for an NHUB32 instead of NHUB22.

More Information for MOTORCRAFT NHUB22

Motorcraft Hub Assembly HUB4 (OEM) vs Motorcraft NHUB32 (Service Design) - Ford Truck Enthusiasts Forums

1999 to 2016 Super Duty - Motorcraft Hub Assembly HUB4 (OEM) vs Motorcraft NHUB32 (Service Design) - I'm looking to replace my hub assemblies, and everything points to Motorcraft Part HUB4 being the OEM part for this. However, both Ford and RockAuto also have Motorcraft Part NHUB32, which has...

www.ford-trucks.com

 

[CDW6212R]

The ABS sensor in the AWD/4WD hubs is very well protected, and should not fail unless something amiss happens inside the hub(grease and bearings), or the wiring is damaged outside etc. So if any truck like that has an ABS issue pointing to the sensor, I take that as a big sign that itt's time to replace the hub.

I took one ABS sensor out early on when I had to replace my first two, looking for a grinding bearing noise etc. The issue ended up being the front drive shaft, its CV joint. That's another subject.

I liked the Ford hubs that I bought the first two times, not knowing if other brands would last. Later I bought Timken hubs, and the last four have been SKF. I think some lesser hubs will probably last several years. I have gone after the top end stuff for the most part. The SKF has the potential to be the best overall at the moment. I gave about $145 for each when I got them a few years ago, a couple were from Amazon, and I think two from RA.

If you have an ABS issue, I suggest buying new hubs and make the truck last longer in the end. I have never had a hub fail yet, though I have replaced all but two original ones in my trucks. The BJ's are typically all junk when you buy the used truck, and doing the hubs also just saves that labor, to only do it once.

 

[J_C]

One other thing. The reason my sensor broke when pulling it out, was probably partially due to sitting next to hot brake components for years, but primarily it was due to the o-ring seal on its shaft, being too far down it (by design) and no gasket between the base of the sensor and the hub, so the top of the hole it mounts in, gets wet, rusts up, and seizes the sensor in. I did use penetrant spray before trying to remove it, didn't make a difference.

When I put the new hub on, I took the sensor off and put a bead of silicone grease around the base of it to try to stop the rust from forming there again.

 

[CDW6212R]

I recall that, I noticed some corrosion at the top next to where it goes into the hub(mine were stock 98k miles parts). I didn't think of that here, I can see that being a problem far up North.

 

[C420sailor]

Had the same happen to me with my rear sensor. Snapped off in the diff. Had to pull the cover to push the stub out.

 

[sehaare]

Had the same happen to me with my rear sensor. Snapped off in the diff. Had to pull the cover to push the stub out.

ouch, while I haven't had to replace that one - yet, that is a hard place to get to in the first place, I could see that being a btch to get out.

 

[Flashflood]

Maybe this is why, I get an ABS light on occasion, when it's cold and stopped or parked in 4WD. Or only in 4wd periods. One hubs been replaced when we got it. The other one hasn't maybe after I get my explorer back I can check this out. I.d.k. Better than replacing the other hub hoping to fix it.

 

[J_C]

^ I was never getting the ABS light, just activation slowing to a stop, below ~10MPH.

If you get the light then there's probably an ABS code set, or a scan tool capable of live data can show the output from all 3 sensors while moving, or lack of output if one is intermittent.

Does your 4WD light flash? Are you certain 4WD is engaging? The rear speed sensor is used for the speedometer so if not getting a signal while moving, your speedo won't be working.

Keep in mind that if your replacement hub was a low quality generic, it could even fail before the other original does, especially if the axle nut was overtorqued, but if this only happens in 4WD then I doubt it's a hub failing. On the other hand, given two factory hubs on same vehicle, same driving environment and one already failed, the other probably doesn't have much life left in it so even if it doesn't solve the problem, I'd consider it something that will need replaced eventually, anyway, not a waste of time.

Don't forget to check the two main wiring harness connectors in the engine bay, though the ABS sensors themselves, are wired to the ABS module and produce a low AC voltage pulse when the wheels spin. Wiring diagram attached.

2nd gen issues? Try this first!

Sometimes a gremlin can be caused by the smallest thing. There are 2 large wire bundle connectors on the firewall. Both are held tight with a 10mm bolt. Any bad connection in either plug can cause just about any issue. from bad transmission shifting, bad o2 sensor readings, no start, no...

www.explorerforum.com

 

[C420sailor]

The rear one isn’t bad to change at all if it goes as planned. But if it snaps it’s gonna cost ya another hour or so and 3qts of gear oil. Still not the worst thing in the world.

Now that I think of it, I had to drive it into the pumpkin after it snapped off...not out.

 

[ynottruth]

1998 SOHC xlt 4WD Rust bucket.

I had an issue with the ABS kicking in just before the SUV came to a stop but no ABS warning light. It would pull to the right and after looking at the brakes, the front Right pads were almost completely worn away while the drivers side had a lot of life left in them.

Before going after the ABS issue I went ahead and did a complete brake job on both axles pads, as it was due, pads, rotors and calipers up front, and pad and rotors in the rear. As I expected, after the brake job the SUV braked perfectly when the ABS fuse pulled, but still had the same pulling issue when the ABS fuse was put back in. So my next step was going to be to pull the driver side front ABS sensor to take a look at it and then initially try cleaning it before replacing it if necessary. Everything up to removing the sensor went pretty quick since I had just removed everything for the brake job a few days before.

When it came to removing the sensor, I made sure to clean out the Allen head bolt that holds the sensor in, so that I didn't strip it out. The bolt came out pretty easy by using just an Allen wrench (no need for an Allen socket). The sensor was in there tight so I started to wiggle it out and finally it came out - or so I thought until I looked at it. The sensor had come apart. What came out was the guts of the sensor with the copper coil wiring exposed. The case that the guts went into, stayed stuck in the wheel hub. No way to get that out without trying to pick it out and probably having broke pieces and rust fall into the hub.

So at this point I have a Motorcraft Wheel hub on order from Amazon. I was surprised to find that none of the local Autoparts store carried the Axle/spindle nut and I had to order that from Rock Auto. I would have just gotten the nut from Ford but I remember from when I replaced the front axle that Ford charged me $25 for that nut and checking this time on rock auto it was under $8 including shipping.

On the positive side, I guess that fact that the sensor fell apart is a good indication that it was the bad one.


So, if you are thinking about replacing the ABS sensor you might be opening up a can of worms like I did.

Try bleeding the abs. I had s similar issue after replacing my hubs on my awd 98, so I used my obd2 tool to bleed the abs system. Hope this helps.

 

[J_C]

^ Can you explain how that would help? ABS only activates if it senses a wheel speed imbalance (even if due to no signal from a fault), while air in the system should only cause poor braking performance, not abs activation. Pulling the ABS fuse to disable it should tell you which is which, air in the system doesn't go away by pulling the fuse.

 

[ynottruth]

^ Can you explain how that would help? ABS only activates if it senses a wheel speed imbalance (even if due to no signal from a fault), while air in the system should only cause poor braking performance, not abs activation. Pulling the ABS fuse to disable it should tell you which is which, air in the system doesn't go away by pulling the fuse.

When I bleed the abs it also rest the abs system. Maybe is just my tool...

 

[J_C]

^ So your problem was the light staying on, not that it continued to activate the ABS slowing to a stop?

 

[ynottruth]

When I bleed the abs it also rest the abs system. Maybe is just my tool...

*reset

^ So your problem was the light staying on, not that it continued to activate the ABS slowing to a stop?

No. My light was not on at all. My problem was the abs activating and pulling one side then the other while driving. Mine is an awd

 

[Flashflood]

*reset

No. My light was not on at all. My problem was the abs activating and pulling one side then the other while driving. Mine is an awd

Sounds like a sensor in that case! Or your transfer case.

 

[ynottruth]

When I bleed the abs it also rest the abs system. Maybe is just my tool...

Sounds like a sensor in that case! Or your transfer c

Sounds like a sensor in that case! Or your transfer case.

Idk. It went away after bleeding the system with my obd2 tool

 

[J_C]

Seems strange and makes me wonder if it was just pulling from braking with air in the system and not an ABS (per se) problem, that ABS wasn't activating, so pedal only sinking from compressing air in the line.

 

[Flashflood]

Idk. It went away after bleeding the system with my obd2 tool

Nice that's what made mine go away God I wish gms were as easy as this lol.