No signal from left front wheel speed sensor

TERRY SCHENK

MEMBER
2010 MAZDA 5
2.3L
4 CYL
2WD
120,000 MILES

ABS/traction control dtc.

Wednesday, July 29th, 2020 AT 8:10 AM

3 Replies

BMDOUBLE

MECHANIC
1,139 POSTS

The first thing that hits me is a faulty front wheel hub bearing failing and taking out the sensor. If the hub has already been done and/or sensor has been replaced, check the circuit in the way that I have shown by applying voltage to one side then placing a load, like a headlight bulb, horn, window motor, etc. On the other side to prove out the circuits. If the circuit proves good, try swapping sensors left to right, if things are the same the only thing left is the module.

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Wednesday, July 29th, 2020 AT 9:38 AM

TERRY SCHENK

MEMBER
20 POSTS

My sentiments exactly I greatly appreciate the test procedure will do that now and will let you know how it goes. And the hub has been checked and sensor replaced only thing is I do not see any type of tone wheel on this thing I pulled sensor and can clearly see entire seat area and there is no tone wheel or magnet or anything visible is that normal if so what does the sensor use as a reference.

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Wednesday, July 29th, 2020 AT 10:42 AM

STEVE W.

MECHANIC
12,950 POSTS

There is a magnetic encoder ring on one of the seals on the end of the wheel bearing. If you could see the magnetic field it looks like a lot of small bars on the face of the seals surface. The sensor reads that surface. If the bearing was replaced just before the loss of signal it is possible the bearing was put in backwards. If not then the magnetic surface may be cracked or has failed. The image shows the magnet side, it is normally flush with the edges of the bearing while the non-encoder side has a recessed seal.

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