ABS Wheel Sensor zero MPH

Crobe · May 27, 2018

The ABS, VSC & VSC Off warning lights are lit on my Nov. 2002 Lexus SC430.

Using Techstream GTS Diagnostics > ABS/VSC/TRAC > Data List, I discovered that the Rear Right Wheel Speed was not registering any speed. All 3 other wheels register a speed as I drive, but not the Rear Right. It stays at zero MPH. However Techstream did not show any DTC error codes?

I assumed that the Rear Right ABS Wheel Speed Sensor was faulty so replaced it with Lexus part no: 8954524030. I reconnected Techstream which cleared the ABS, VSC & VSC Off warning lights. However, as soon as I drove a short way these lights returned & the Data List showed Rear Right Wheel Speed was still not registering any speed.

The problem is obviously not the RR ABS sensor. (Both the old & new sensor show ~ 1,069 ohms).

How may I diagnose deeper what the real problem is?

C Andrew Green · May 27, 2018

My thoughts:

Is there a voltage at the connector where the ABS sensor is plugged in? Maybe check continuity back to the ABS ECU.

Is the ABS (I think it's called a reluctor?) ring secure, undamamged, in the correct place, not too rusty and in one piece (not split)?

Does the the ABS ECU need a jolly good restarting by disconnecting the vehicle Battery for a time?

I'm not a mechanic but had some hassles with ABS on my old Mazda 626 and ended up remaking / rewinding an ABS wheel sensor.

Andrew

Neil E · May 27, 2018

Sounds familiar, this may help you.

https://forum.lexusownersclub.com/threads/abs-vsc-problem.2802/page-2

Crobe · May 27, 2018

Thanks Andrew. I've tried the "disconnecting the vehicle Battery for a time" and I get 2.57 Volts at the ABS connector, so I think the circuit to the ABS ECU is OK. Reluctor ring secure, but Neil's link may be the answer.

And thanks Neil, I did indeed have many iron filings on the sensor when I removed it, and the sensor did seem quite a distance from the reluctor ring, tho' it's castellations still looked quite prominent. It looks a massive job to replace the reluctor ring, so before I resort to that, and as I seem to have two good sensors, I thought I'd try filing down the shoulder of one ABS sensor so it gets closer to the reluctor ring! What do you think? I'll also check for rust & release the hub collar if it's grinding the reluctor ring.

I'm away on hols, but will let you know how it goes mid June. Thanks again guys.

Crobe · May 28, 2018

Had time to take another peek down the ABS sensor aperture. I must have been dreaming thinking I saw castellations last time I looked. As you see, the reluctor ring has been worn smooth!! That's my problem. Thanks again Andrew & Neil. I'm now on the hunt for a new reluctor ring.