ABS sensor change

[PUKU]

Does one have to reset the ABS System, somehow, after changing a sensor? I ask because I have just replaced the rear O/S sensor and the the ABS is literally going haywire. Brakes are coming on and off at random when accelerating or braking but more worryingly when breaking hard the car will not stop. No ABS or other warning lights are on although VSC did flash on momentary. No lights remain on

When the sensor is unplugged all is well; running as if no ABS is fitted, (lovely - I'm in control again!). Obviously VSC,ABS and H/Brake warning lights are on.
I have tried the "disconnect the Battery for a while" bit but no difference.
I am wondering; I ordered the sensor as a rear right. Silly question ... is that right facing the car or right looking from behind - Offside.
I want to explore all avenues before I have to send the car in to be looked at (costly)

Any help would be very much appreciated.

The car is an RX300 year 2000.

 

[kenhall]

Sounds like a duff or incorrect sensor or less likely a damaged toothed ring.  What made you decide that this particular sensor was faulty? Where did you buy it from? I’m unfamiliar with the type of sensor on an RX300, however the sensors fitted on my RX400h have a resistance of 1725 ohms (coil and magnet type). In my experience of similar sensors on Citroen cars they mainly fail due to going open circuit which causes the ABS self diagnostics to turn off the system.

No requirement for resetting ABS normally unless a permanent fault code has been logged which would require a diagnostic (Techstream) connection to clear.

You are correct Right=Offside in the UK

[PUKU]

I had juddering during breaking; a diagnostic check flagged up the sensor. During the removal the old sensor did breakup so internal damage may have been possible. I will (once again) strip the hub down and check.

Thank you so much for the information, I had a feeling that there was no need for resetting but never 100% sure on modern cars!

[m4rkw]

On 8/13/2020 at 5:08 PM, PUKU said:

I had juddering during breaking; a diagnostic check flagged up the sensor. During the removal the old sensor did breakup so internal damage may have been possible. I will (once again) strip the hub down and check.

Thank you so much for the information, I had a feeling that there was no need for resetting but never 100% sure on modern cars!

Was actual diagnosis done by an experienced technician or did you just scan the codes and see a sensor error code and assume the sensor was faulty? Error codes are not specific faults they are error *conditions* usually with hundreds of possible causes. If you bought a cheap sensor off eBay you may have simply added another problem to the one that was already present.

[PUKU]

Yes it was with a professional scanner operated by a skilled tech, that backed up my scanner findings.  When the sensor was made ready for replacing it was found badly corroded and broke up easily.  I have checked the new one now and found an impedance of 1.075ohms where the assumed correct reading should be nearer 1725 ohms

[Herbie]

2 hours ago, PUKU said:

I have checked the new one now and found an impedance of 1.075ohms where the assumed correct reading should be nearer 1725 ohms

I'm not quite sure if that's right but it's a bit of a confusing item.

The workshop manual I have is for model year 2003 onwards so the difference may be down to that, but if the manual is correct then neither of your values are actually within spec.

[PUKU]

That is worrying, although I will have to refer to my 2000 WSM as knowing Lexus there is bound to be SOME difference. It is a lovely vehicle, reliable and pleasant to drive (All over UK) but when something goes wrong .....  Out of interest Lexus wanted over £180.00 for their sensor!

[m4rkw]

10 minutes ago, PUKU said:

That is worrying, although I will have to refer to my 2000 WSM as knowing Lexus there is bound to be SOME difference. It is a lovely vehicle, reliable and pleasant to drive (All over UK) but when something goes wrong .....  Out of interest Lexus wanted over £180.00 for their sensor!

It was probably a bargain given that yours doesn't work 😛

[PUKU]

Does make you think about that! 

I have now checked the readings again, yes there is a difference on the values required. (year 2000 to 2003). Plug terminal to terminals was just out of spec at 1.09-1.106 k ohm.. (Required 1.5 k ohm - 1.7k ohm) but open circuit to body ground so that puts that sensor back to the supplier as faulty. 

Got another on order from different source and if that goes gaga then Lexus here I come!  (Probably go that way anyway but when after market ones are £15-£30 ... 'nuff said!)

[PUKU]

Now have a replacement. Took readings Through the plastic bag before opening!, and we have 1.057 k/ohm.

Any Thoughts?

Out of interest I decided to check the N/S one as well. Same as the offside, completely jammed in the hub due to rust and crud, had to destroy the old on to get it out - so here we go again!

[m4rkw]

If it’s out of spec send it back and buy from Lexus

[PUKU]

Is there a way of clearing the error codes without an Analyser. My Autell only does the engine not the ABS/Brakes.  I am not worried as it is lovely driving without ABS but with a MOT looming .....