Wheel Speed sensor issues

[Ed Kennedy]

It's the right rear sensor that's bad. But I've got a lifetime warranty on those so I'll just trade them out. If it goes out again, I'll grab OEM from Ford. May grab some to have extra anyway if history with them is an indicator of the likelihood of it happening again. That Jeep had so many issues with it I swore I'd never buy another.

Sponsored

 

[airline tech]

Ok, you have pinpointed the location, with this being a repeat issue and unknown if it was the same sensor from the first issue.
I would pull the sensor, jack up the truck and visually look at the encoder while you spin the axle, look for any debris stuck in one spot or damaged teeth.
next, would be a wiring integrity check for the RR

Disconnect the ABS connector C135 and the RR sensor C426
Ohm between:
Pins 17 & Pin 1 - Sensor High Circuit
Pins 29 & Pin 2 - Sensor Low Circuit

Alternate procedure - Jumper Pins 17 & 29, then meter between pins 1 &2 on the RR sensor connector, all you are doing is checking for wire integrity.

Should measure 3 ohms or less

Note: This circuit goes through 2 inline connectors
C421 & C408 - if you have a higher resistance reading

It goes through C421 before C408 - Going from rear - forward, I do not have a detailed pinout of that connector yet or its detailed location (on the left rear frame)
but if needed I can dig some more.
I am pointing out C408 - this connector has been problematic for corrosion and may just have a dirty connection for the pins of the wheel speed sensor.

So if issue is found - you can isolate the circuit down - and jumper pins 9 & 10 on the downstream connector and do the same meter test as above on C426 (Pins 1 & 2)

RR @ C408
Pin 10 - Feeds Pin 1 on C426
Pin 9 - Feeds Pin 2 on C426

If you want to roll the dice and guess its just a bad from stock sensor, just replace it, but if the issue returns again then it needs a deeper diagnostic of the encoder, RR wheel bearing for roughness and the wiring checks.

 

[RangerBill]

It's the right rear sensor that's bad. But I've got a lifetime warranty on those so I'll just trade them out. If it goes out again, I'll grab OEM from Ford. May grab some to have extra anyway if history with them is an indicator of the likelihood of it happening again. That Jeep had so many issues with it I swore I'd never buy another.

Do you still have the original sensors? If so, try putting the original Ford sensor back in. Maybe that RR sensor was ok. Since all four were replaced without knowing which one was originally bad, the RR Ford one might be ok.

 

[Ed Kennedy]

Ok, you have pinpointed the location, with this being a repeat issue and unknown if it was the same sensor from the first issue.
I would pull the sensor, jack up the truck and visually look at the encoder while you spin the axle, look for any debris stuck in one spot or damaged teeth.
next, would be a wiring integrity check for the RR

Disconnect the ABS connector C135 and the RR sensor C426
Ohm between:
Pins 17 & Pin 1 - Sensor High Circuit
Pins 29 & Pin 2 - Sensor Low Circuit

Alternate procedure - Jumper Pins 17 & 29, then meter between pins 1 &2 on the RR sensor connector, all you are doing is checking for wire integrity.

Should measure 3 ohms or less

Note: This circuit goes through 2 inline connectors
C421 & C408 - if you have a higher resistance reading

It goes through C421 before C408 - Going from rear - forward, I do not have a detailed pinout of that connector yet or its detailed location (on the left rear frame)
but if needed I can dig some more.
I am pointing out C408 - this connector has been problematic for corrosion and may just have a dirty connection for the pins of the wheel speed sensor.

So if issue is found - you can isolate the circuit down - and jumper pins 9 & 10 on the downstream connector and do the same meter test as above on C426 (Pins 1 & 2)

RR @ C408
Pin 10 - Feeds Pin 1 on C426
Pin 9 - Feeds Pin 2 on C426

If you want to roll the dice and guess its just a bad from stock sensor, just replace it, but if the issue returns again then it needs a deeper diagnostic of the encoder, RR wheel bearing for roughness and the wiring checks.

I looked at the ring teeth earlier and didn't find problem but might as well look again. I tested the plug earlier today and it tested out good. I'll clean it all up before I put another sensor on. I think you're onto something though but I just haven't found it yet. I'll go through it all tomorrow. Could be dust from a recently reworked road I drive that's got a lot of dust. Could be the aftermarket sensor too. Had a similar thing with that on the jeep. I'll take my time and work through it. Just glad to know it wasn't the module! This thread has been great! Appreciate everyone's help/advice!

 

[Ed Kennedy]

Curious, I might try to clean the teeth just to cover everything. What's the best route to do that?

 

[got3fords]

Curious, I might try to clean the teeth just to cover everything. What's the best route to do that?

Toothbrush of course.

 

[DukeCanBuildit]

Toothbrush of course.

It may actually be the best method but it’s still funny!

 

[airline tech]

Any small brush or small diameter magnet, the encoder ring is magnetized and any metal shavings from the differential can work their way outboard to the encoder and stick to it - sometimes a small piece of debris can stick in between the teeth on the encoder, thus it throws off the Hall-Effect of the sensor.
So really all that needs done is to spin the axle and inspect the teeth for any obstruction the sensor would pick up and also inspect the teeth for any damage

 

[Ed Kennedy]

Cleaned it all up but it really wasn't very dirty at all. Cleaned the two plugs to be sure and did find the one on the axle was a little loose, so I fixed that and dropped in the sensor and it's all good so far. I'll go back over the complete wiring one more time tomorrow to double check that.

 

[airline tech]

If the RR was not secured- that might have been the issue.

 

[Ed Kennedy]

Well, well, well.....back again with same sensor issue, so I've definitely got a problem on the RR wheel area. Tone ring? Bearing? I don't know.....but it's frustrating. No trash on sensor or in splines still.... no bearing noise when turning (will check looseness today). No loose or bad wires that I can find (checked that connector again).

 

[RangerBill]

Well, well, well.....back again with same sensor issue, so I've definitely got a problem on the RR wheel area. Tone ring? Bearing? I don't know.....but it's frustrating. No trash on sensor or in splines still.... no bearing noise when turning (will check looseness today). No loose or bad wires that I can find (checked that connector again).

Did you use an aftermarket or Ford sensor?

 

[Ed Kennedy]

Did you use an aftermarket or Ford sensor?

I didn't and that's going to be the cheapest first try I guess, assuming I don't find another issue when I inspect the hub/axle.

 

[airline tech]

I have a feeling you have an issue with the wiring, most likely on that connector - Worn & Spread contacts.
They make Flex-Probes (Test Leads) that are an exact fit for wire checks, this probe also allows for a (resistance check) of the contacts (how easy can you pull the probe out of the connector)

You can do some wire checks that I previously posted or you can try and replace the harness from C421 back to both rear sensors.
If you follow the RR harness forward you will come to a 6-cavity connector, at this connector
it splits off the LR & RR ABS Sensors and (IF INSTALLED) will have 2 wires for the (Elec Lock Diff)
I do not have an exact location of C421 but its somewhere near or above the spare tire.
If you can, you may try and see if there is a way to spread the contacts out, so they have a tighter grip on the RR Sensor.

The Base PN of the Harness is: 2B572
I cannot locate the exact PN as they differ if you have the ELD, but somewhere on the harness is a white parts tag - Possibly LB3T-2B572-BAA, this will be the engineering PN and will need to cross this PN over to the (KB3Z ?) as the most likely prefix

Again it really needs a wire check with a (shake) test to ensure wire integrity on that circuit if there is an issue it will show up on a shake test.
With C408 being a known problem area for corrasion, I would also check that connector (Pins 9 & 10)

 

[Ed Kennedy]

I'll start with wiring and work to hub if nothing found. The issue is happening intermittently right now, it comes and goes, so a bad connection sounds like a possibility.

Sponsored