Hello everyone,
I have been looking for information on this forum for a while and I am running out of ideas and even hope. I even ask advice from chatgpt, but the more I explained, the more nonsense it got. If I stayed any longer it would have suggested me to check the carburetor. I bought my 2001 2 years ago, with the same fault on the dash. Vsc off- abs - vsc. I did diagnostics: Rear speed sensor LH circuit and ABS control system malfunction. I got a new rear abs sensor with the car, what I replaced. Replacing the sensor I noticed that the ring was worn out bad because of the corrosion on the hub pushing the dust shield against it. I replaced the ring and still same issue. I used diagnostic device to read speed signal while driving, right side is reading good, left side is 0. I ran a wire from left side sensor plug to right side body loom, and the sensor itself reads fine. Thinking maybe the left harness having some damage, I measured the resistance from the under dash abs control unit plug, Have the same resistance as measuring from the sensor plug, 1.1kohm. Same resistance as the other side. Thinking maybe the left channel has burnt out on the control module, I replaced the module under the dash. Going for a test drive with high hopes I came back with anger and despair. I also ran a new pair of wire from under the dash to the sensor and still nothing. The car itself runs fine, brakes are good, no abs and skid control. The hydraulic booster sometimes whines under the bonnet after starting up cold. Its not making sense to me anymore, what am I missing?
Thank you in advance!
Martin

 

 

Did you check to see if the new sensor is seated in all the way?
Is the new sensor OEM? some times those aftermarkets are not made to exact spec and dont let the sensor seat in all the way.
Did you check the tone ring inside the hub for debris or water?
Did you clean the rust off the inside of the hub before you replaced the dust cover (what Toyota calls it..lol) for the ABS sensor?

if the sensor is not seated in all the way its enough to throw off the signal.
if the dust cover ring becomes damaged or pushed out due to rust it will damged the tone ring inside the hub.
if you already checks for an open circuit in the wiring and the wiring is good then its gotta be a issue within that area. ABS ECU is the least likey issue.

 

Hello, thanks.
As I mentioned in the post, I checked the ring and replaced it. The sensor and the ring are fine as when I took 2 long wires and connect the left side sensor to right side body connector, I get a good steady speed signal from the sensor, just showing as right rear wheel on the diagnostic tool. When I connected right side sensor the left side body connector, there is no speed signal from either side. I even cut the wires behind the abs ecu and switch sides in there and still left channel stays 0. I changed abs ecu twice, still the same. All except the brake booster has been checked now. I have no idea what it might be.

 

The ABS speed sensors dont go through the brake booster/ABS acuator directly.
Might be a long shot did you check to see if the short pin in the DATA 1 (OBD) connector is in the right place?