Abs, Vsc, Vsc Off And Speedometer Not Working

[MackScania]

Hello,

I'm yet another victim of the above problems. I have tried to search for an answer but I can't find anything that points me in the right direction.

I've had diagnostics run and was advised it was the Rear Right speed sensor. They had to remove the hub to get the sensor out as it was stuck so I was advised the ABS ring was fine. Unfortunately this cleared the code, but not my problems.

I've just tried replacing the ABS ECU with a used one from eBay which has not altered the problem in any way.

The weird thing is, if i plug a hand held diagnostics computer into it (it advises communication failed), the lights go out except the ABS light. When the vehicle starts moving all three lights illuminate again and the speedometer starts working once at a speed of 20mph+ but after returning to a stop the lights go out with the exception of the ABS light.

Eventually (5-10 minutes) the speedometer stops working and all three lights remain on constantly.

Can anyone shed any light on my problem.

The brakes feel fine.

P.s. 1998 GS300 with 70,000 miles

[steve2006]

If you have a digital multimeter you can measure the resistance of the sensors, IIRC they should read around 1200-1500 ohms, if you don't get any reading the sensor is open circuit and therefore faulty.

Just disconnect the sensor at the plug/socket and measure across the 2 pins.

[MackScania]

Thanks for your reply, were are the speed sensors plugged into?

Thanks

[TigerFish]

Pre 2001 models are not odbii compliant which is why the reader won't work unfortunately.

You should be able to read the codes by using a paperclip and counting the flashes of the abs light. I can't locate the details on my Iphone, but will try and find them when I get on my laptop.

Sent from my Iphone using Lexus OC

[MackScania]

This sounds promising! I look forward to your reply. I assume the paper clip will go into the diagnostics port under the bonnet??

[MackScania]

I've checked the rear speed sensors and they show the resistance as 1.2 ohms so i beleive they are fine. I've replaced the ABS ECU under the dash with a used part from eBay. Speedo worked for 2 seconds then stopped.

Would I be right in saying its time to replace the brake control unit under the bonnet?

I've heard I should replace it with an 02-05 model part, is this just plug and play or would it need modification?

Thanks

[dave1]

I doubt if that will cure anything as you don't appear to have the faults associated with failure of the unit.

[KentIS300]

old thread resurection. But I put here the most likely cause to the problem.

I had the same symptom to mine GS300 '98 model and the problem was the "swelling" of the rear hubs. They get rusty internatly... and they wear off the teeth of the ABS rings.

So the sensors cannot pick up correct the gaps etc.

The sensors are fine in most cases with no damage like it was at mine.

The fact you loose the speedo, it is the both wheels loose signal at some point... which indicates issues on both hubs.

If you have problem to one wheel only the speedo should not fail. But you will have the lights on the dashboard (christmas tree like lol)