Rear Wheel Speed Sensor

[Gen5RangerPegasus]

I have a question for anyone who has a 19-23 Ford Ranger.

I have a ABS/Trac light come on intermittently. Every time I turn off the truck and drive a short distance it goes off and will come back on here and there. Sometimes not at all. I plugged into the OB2 awhile ago and found I had a RR wheel speed sensor that is misreading etc. When I pulled the sensor it appeared damaged and has diff lube on it. I have no external leaks. I know this sensor is my culprit. I attempted to replace it but light stayed on without going off at that point and I am assuming it was because of the fluid in the carrier tube. When I pulled the new sensor out it was like I dipped it in fluid. Needless to say I put the old sensor back in and got my intermittent back.

Here is my question. Is the differntial overfilled or is the seal failing? If the seal was failing would it not leak externally and Isn't the sensor behind the seal inside the tube?

I know I can check the vent tube, which I have not done yet. Thoughts?

Let's Talk.

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[RangerBill]

I have a question for anyone who has a 19-23 Ford Ranger.

I have a ABS/Trac light come on intermittently. Every time I turn off the truck and drive a short distance it goes off and will come back on here and there. Sometimes not at all. I plugged into the OB2 awhile ago and found I had a RR wheel speed sensor that is misreading etc. When I pulled the sensor it appeared damaged and has diff lube on it. I have no external leaks. I know this sensor is my culprit. I attempted to replace it but light stayed on without going off at that point and I am assuming it was because of the fluid in the carrier tube. When I pulled the new sensor out it was like I dipped it in fluid. Needless to say I put the old sensor back in and got my intermittent back.

Here is my question. Is the differntial overfilled or is the seal failing? If the seal was failing would it not leak externally and Isn't the sensor behind the seal inside the tube?

I know I can check the vent tube, which I have not done yet. Thoughts?

Let's Talk.

Was the new sensor a OEM Ford part? If not, I would only use a Ford sensor as others have had issues with aftermarket wheel speed sensors. The axle seal is leaking if you have oil on the sensor and will need to be replaced.

 

[Gen5RangerPegasus]

Aftermarket.

 

[airline tech]

To clear this up - yes its normal to have oil on the sensor, it lives in the oil supply gallery for the bearing.
What needs inspected - is the encoder (tone ring) for metal shavings or debris build up that is being pushed down the tube from the gear sets, rotate the axle and visually look down the sensor hole and inspect the encoder ring.

Yes - it has been noted that some aftermarket sensors, also will generate codes and the conclusion I have come to for the reason is:

The ABS Module is highly sensitive to the - (High-Low) pulsed signal being generated and the signal quality of that signal is very important - so how accurately the sensor is reporting the transitions of the spinning encoder.

1. Frequency = How fast the encoder is spinning

2. Signal = How accurately the sensor is communicating the transitions (High-Low) pulses, I think this is where the Aftermarkets are having the issue and the ABS Module does not accept the signal as believable (its not accurate enough) for the sensitive ABS Module and I think that since the wheel speed sensors tie into other functions (Can Bus) signal driven - Traction Contral - Hill Start Assist and AEB Etc, I think this adds to the sensitivity issue
The signal is generated by the missing tooth (spacing) on the encoder wheel, if there is debris build up on the teeth it can generate a false signal
The signal itself is a magnetic field - so over time the encoder can attract metal debris to it from the gear sets (shavings etc)


So not only the quality and accuracy of the sensor, but the length (air gap) of the sensor also factors in - do the aftermarket and ford sensors - match exactly (gap) between the sensor tip and the encoder wheel when its installed, so something as simple as a different thickness of the mounting flange would pull the sensor farther away from the encoder.The Aftermarket issue is just my theory on why they do not work correctly on the 5G Ranger a true test would be - get the 2 side by side and note the differences and then live data monitor or even better lab scope the frequency between a new or known good sensor to the aftermarket sensor and note how much of a signal difference - that is being reported, since this is what the ABS Module is flagging

Plus we need to factor in - poor connections between the sensor connector and the ABS Module

Now for this specific issue - Damaged Sensor Tip

This can be caused by either issue

1. Bad Bearing or not normal axle play, allowing the encoder wheel to contact the sensor tip.

2. Gear sets - metal shavings caught up in the encoder wheel and the metal shavings hit the sensor tip.

A. Get the wheel off the ground and shake and pull on the axle, any major play noted.
B Drain the differential fluid and check for abnormal metal debris

 

[Gen5RangerPegasus]

It's normal to have "oil" or "diff fluid/bearing fluid" on the sensor?

So what I am gathering is that my assumption is correct - the sensor lives behind the axle seal, recieves lubrication from the differntial fluid at the gear housing, and that it travels down the carrier axle tubes. I have no external leaks and I have checked the play in both of my rear wheels.

When I have time (next day or two) I will pull the sensor and take a picture of it. I don't know if I will be able to get a good look at the tone ring. That was what I was suspecting may have been damage as I did have grey discoloration and an abnormal amount of fluid build up on the wheel speed sensor. When I took it out and cleaned it, my thought was that the shavings and build up of fluid on the sensor have degraded it's integrity. Using an aftermarket sensor (too cut costs) did not help me find a solution. However, I do not want to throw good parts at this truck and not fix the causation of the failing sensor. I am not sure if a small amount of shavings is normal or not on a truck with 100k on it.

I was a technician by trade and went to an automotive technical school before I switched careers, so I have a little know how. I wanted to get some input on this design and to help determine if I need to order two new rear axles with bearings since they are sold as an assembly. I am looking to put a locker of limited slip differential in the rear, and I was considering that if I am going to rebuild the entire rear end that I should do it when I buy the replacement parts. In the meantime I do want to get rid of the ABS trouble code symptom. With your advice I can check the tone ring for damage, and buy a new OEM sensor. Now that I think about it I do recall the flange size being a difference on many aftermarket parts creating an air gap as you have mentioned. Pretty common I would say.

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