Wheel speed sensor woes

[ko2]

Hey all, my 2006 LX470 has had an intermittent issue with the wheel speed sensor throwing codes. I narrowed it down to only happening when it rained/was damp out. During winter this meant it would happen often, and during summer it happened very rarely. I left it most of the year assuming it would be an easy fix.

Recently I checked techstream and confirmed the front right wheel speed sensor. Ordered a replacement (non-OEM part, Wells brand) and used the stab-the-old-sensor-with-a-pick-until-its-gone method of removing the old sensor. Installed the new one and.... it's even worse now. Now the code is always on. I unbolted the new sensor to check it out, and it had some metal shavings on it. Cleaned that off and still nothing.

At this point I found out I could get live readings of the wheel sensor, and it shows as 0 mph. It isn't reading any speed no matter how fast I go.

Despite working on my vehicles for almost 20 years (has it really been that long?) I'm horrible with electronics. Does anyone have any ideas? Have you experienced this before?

(Apologies the pics are huge)

 

[scubadoober]

You can ohm the sensor, if it show O/L it is dead.

 

[Dirt J]

Could the upstream wiring cause the issue? (Not the actual sensor)

 

[ko2]

You can ohm the sensor, if it show O/L it is dead.

I'll definitely check that. Just read up on the method for doing that.

Could the upstream wiring cause the issue? (Not the actual sensor)

Good point. The harness looked good from the engine bay though I suppose it could have an issue anywhere from the engine bay to the ECU. Any idea which ECU the wheel speed sensor go to?

 

[GerLC100]

Sensor picks up the signal from the rotor right? Is it clean inside there?!

 

[ko2]

Sensor picks up the signal from the rotor right? Is it clean inside there?!

It looked a bit crusty in there. The confusing thing is that it was an intermittent problem before I replaced the sensor and after replacing the sensor it doesn’t read at all, which is what led me to think it was electrical.

I’ll definitely remove the sensor again and look closer as there is a chance some debris got loose when I removed the old sensor.

 

[scubadoober]

The sensor picks up from the back side of the hub. However, it can get clogged up with metallic dust. Not a bad idea to blow it out with brake clean/compressed air. Probably not your issue unfortunately. Do you have a multimeter that reads resistance (ohms)? You can disconnect the plug in the engine bay and test without further removal. There are only two pins, and polarity doesn't matter for the test.

 

[badlander]

You can clean the sensor ring by reaching in thru the sensor hole with a q tip and slowely rotating tie wheel a little at a time. Clean each and every notch thoroughly using solvent on the q tip. Mark the tire so you know you made it all the way around.

 

[ko2]

View attachment 4024018
The sensor picks up from the back side of the hub. However, it can get clogged up with metallic dust. Not a bad idea to blow it out with brake clean/compressed air. Probably not your issue unfortunately. Do you have a multimeter that reads resistance (ohms)? You can disconnect the plug in the engine bay and test without further removal. There are only two pins, and polarity doesn't matter for the test.

Thanks! I went out last night and tested the plug. I set my multimeter to ohms, which made it read o/l, then when I touched the pins and it continued showing o/l. That, plus the fact that techstream showed that the new part didn't register any speed is leading me to believe the sensor is bad. (my first rock auto part failure in many years)

My plan is to trace the driver-side harness (with a functioning speed sensor) and test that one to be sure it's not a problem with my multimeter.

Question regarding blowing out the backside of the hub. Is there anywhere for all that crap to go?

 

[ko2]

You can clean the sensor ring by reaching in thru the sensor hole with a q tip and slowely rotating tie wheel a little at a time. Clean each and every notch thoroughly using solvent on the q tip. Mark the tire so you know you made it all the way around.

I appreciate your help, today is the last sunny day before snow is supposed to fall so I'll be taking this on. I asked in my last post a couple minutesago but I'll ask you too: When I clean out the sensor ring will any junk I scrub off fall out of there?

 

[badlander]

If you keep the q tip moist most junk will stick to it and you can just keep changing to new q tips. Some debris may hall inside but it will fall straight down and just stay there out of harms way. Rotate the tire so the ring rotates upward so as you clean you continue to pick up some of the stuff that may fall downwards and stick back on the ring as it falls.
Obviously the best way to service it is to remove the hub, but a ton of extra work.

 

[scubadoober]

The wires are very thin and delicate. I pinched mine replacing the upper ball joint, and the insulation was still intact. Threw a code on the test drive, there was no continuity when tested. Found a good used one on ebay, and replaced.

 

[ko2]

Update: The sensor does seem to just be dead based on my testing. I don't remember crushing or damaging it in any way, but I suppose that could have happened. Cleaning and vacuuming (not sure the vacuum did much) out the ABS ring as best I could made no change. I ordered an OEM sensor from partsouq. I'll update when I've installed the new part.

Thanks to everyone for their help with this!

 

[ko2]

Final update:
I installed the new oem part, cleared codes and the problem is now solved. Pic included shows all wheels registering speed (just driving up and down the driveway) where the previous part showed 0 mph all the time.

For anyone who sees this in the future:
I ordered a Wells brand wheel speed sensor that tested as inoperable upon install. It didn’t register any speed in techstream. There were no cuts or pinches that I could see. I ordered an OEM part from Partsouq and it solved the problem.
Unfortunate waste of $120 CAD but I’m just happy all the codes are gone.

Big thanks to everyone for their help with this!