ABS Reluctor Ring Chafing Wheel Speed Sensor (2007 Tacoma)?

[john_pifer]

This issue started in November with the ABS/Brake warning lights illuminating. I have a thread on that issue HERE but I wanted to start a new thread about this, in hopes that more people will read it, and also hopefully it'll come up in search results in the future, when somebody else has this problem. Anyway, I pulled the left rear wheel speed sensor, and, it did look a little funny, but, initially I didn't look too hard at it. Put the new sensor in, warning lamps blinked out, and all was good...until a day later on my way to work, when they came back on. I pulled the new one that I had installed, and obviously something inside the hub was making contact with it - enough to wear all the way through the outer plastic housing, to the point where the copper internals are showing. I called a local independent shop, and they said it almost has to be the ABS reluctor ring (looks like a gear on the axle shaft - this is what provides the wheel speed input to the sensor). His guess was that the ring has somehow come loose and is now making contact with the sensor. I was already planning to go on and change the wheel bearings/housings, as well as the seals (gear oil is not showing - yet - on the outside of the drums, axles, or wheels, but the wheel speed sensors have gear oil on them when I pull them out). My question is, who's seen this before? What's going on here? My plan is to pull the axles and have a local machine shop press the old wheel bearings and components off the axle shafts (I don't have the necessary press, nor do I have room in my small garage for one), and press the new components on, then re-assemble everything myself. I was just wondering if anyone's seen this, especially on a Tacoma, 4Runner or similar Toyota, and has gone through this before. Goal is to do this right the first time and avoid a rework due to leaking again, so, just wanting to arm myself with as much information as possible. Here are photos of wheel speed sensors. Upper left is original, OEM sensor. Upper right is the new (eBay) sensor. You can tell that the original sensor was being rubbed, but the new one got rubbed much worse. Bottom one is a new (RH side) sensor, for comparison.

 

[14Accent]

Why is the eBay sensor so much smaller? Is that just the angle? That being said, maybe pull both rear sensors and look through the bore at the tone ring. If it's only happening on the left side, the problem should be obvious. ABS rings are pressed onto the axle shaft, and it's not unheard of for them to break. Mid 2000's Ford Escape's are notorious for this. What I don't get, however, is how the sensors got worn on the sides. Those sensors should be reading the gaps from above, not from the side. The only sensors I've seen that read from the side are the type where the tone ring is a magnetic strip embedded into the bearing itself. I'm interested to hear what you report back with.

 

[CharBaby]

My experience with Toyota/Lexus is to stay with OE on just about everything. I've had issues with reluctor rings on a Lexus where it cracked and caused the ABS light to appear. Also, during normal stopping even on dry pavement, the ABS would pulse at every stop. So, I disconnected the electrical connector from the proportional block till I got it fixed properly. Needed to replace the reluctor ring on the axle shaft.

 

[andyd]

Just hearsay But I've <span style="font-style: italic">heard</span> that loose or broken rings can be epoxied back into place.

 

[Audios]

Your wheel bearing has play and is allowing the axle to hit the sensor. This is common on GL's like mine and heavier MLs like with the 500 or 550 engines.

 

[john_pifer]

Originally Posted by 14Accent

Why is the eBay sensor so much smaller? Is that just the angle? That being said, maybe pull both rear sensors and look through the bore at the tone ring. If it's only happening on the left side, the problem should be obvious. ABS rings are pressed onto the axle shaft, and it's not unheard of for them to break. Mid 2000's Ford Escape's are notorious for this. What I don't get, however, is how the sensors got worn on the sides. Those sensors should be reading the gaps from above, not from the side. The only sensors I've seen that read from the side are the type where the tone ring is a magnetic strip embedded into the bearing itself. I'm interested to hear what you report back with.

The eBay sensor is the same size - same dimensions. It's just the camera angle making it look smaller. It is interesting how it's worn on the outboard side. The part of the sensor that has been chafed faces outboard. The left rear sensor mounts into the cavity from the front, with that mount hole you can see in the photo pointing down, and the plug pointing forward. I haven't disassembled yet, but it seems to me that if it was the tone (reluctor) ring hitting the sensor, it would be hitting the end of the sensor and not the outboard side of it. I'll just have to pull the wheel and drum to see.

 

[john_pifer]

Originally Posted by Audios

Your wheel bearing has play and is allowing the axle to hit the sensor. This is common on GL's like mine and heavier MLs like with the 500 or 550 engines.

You're probably right. I'll update this post when I find out what is going on.

 

[CharBaby]

This is what I discovered with these reluctor rings. If my rotors are frozen on the hubs, I have always given the rotors a good )))"WACK"((( with a mallet. Well, maybe a 4lb sledge! If your brake rotors are frozen on the hubs due to rust, ya' can't pound 'em off with a hammer. This pounding, cracks the rings. I found this out the hard way.

 

[john_pifer]

Originally Posted by Char Baby

This is what I discovered with these reluctor rings. If my rotors are frozen on the hubs, I have always given the rotors a good )))"WACK"((( with a mallet. Well, maybe a 4lb sledge! If your brake rotors are frozen on the hubs due to rust, ya' can't pound 'em off with a hammer. This pounding, cracks the rings. I found this out the hard way.

Thanks for the tip. This model Tacoma has rear drum brakes. Easy to remove since they thought to put bolt holes where you can thread in bolts to pull off the drums easily. So, no pounding necessary.

 

[CBR.worm]

I haven't experienced that, but, my first thought would be wheel bearings allowing some movement, or whatever the sensor mounts to is moving.

 

[mattd]

Check the whee bearings. Unless you have a full array of tools with a good press rear Tacoma bearings are not a diy job

 

[john_pifer]

Originally Posted by mattd

Check the whee bearings. Unless you have a full array of tools with a good press rear Tacoma bearings are not a diy job

Plan to do as much as I can, myself. See original post.