Mk2 Gs300 Speedometer Not Working

[garethr]

The VSC and ABS lights have been on, and the code said right rear wheel sensor. Replaced it, no difference, so investigated further today.

Had the car up on the lift, removed the rear sensors, lots of swarf, peered into the holes, found the problem - something had worn down the ABS rings.

Removed a driveshaft nut and tapped the shaft back so that we could see the ring, and could see that something (dust seal?) had been rubbing against it. The other side is also worn own, so need two driveshafts. So far so good.

Put it back together. Drove home, and the speedo was behaving oddly, not reading below about 20, and now it's stopped working altogether, although the cruise control is working perfectly.

Any ideas? I thought the speedometer took its signal from the gearbox. How could we have affected it by messing about with the driveshaft/rear ABS sensors? Just coincidence?

[katana92_uk]

sorry cant help you with your problem

but i recognise your name from TIF and LSOC

[ColinBarber]

the speedo gets its signal from the ABS/VSC ECU which in turn gets its signals from all 4 ABS sensors.

[Steviewevie]

the speedo gets its signal from the ABS/VSC ECU which in turn gets its signals from all 4 ABS sensors.

What is the gearbox speed sensor used for then ?

[garethr]

The speedo gets its signal from the ABS/VSC ECU which in turn gets its signals from all 4 ABS sensors.

Thanks, that might explain it. Perhaps it could deal with one rear wheel sensor not working, but now we've disturbed the other rear sensor and two aren't working.

What is the gearbox speed sensor used for then?

The gearbox is working as normal, and, as I said, so is the cruise control, so those speed signals appear to be OK.

[garethr]

Sorry cant help you with your problem but I recognise your name from TIF and LSOC

That's me. I still have the Soarer.

[MackScania]

I have the exact same problem at the moment, speedo not reading below 20, then eventually after a slow crawl in traffic, stops working altogether. If I plug in a diagnostic handheld tool, it doesn't read the codes, but it does appear to reset whatever is stopping the speedo from working.

Garage replaced the Rear right speed sensor with no success. They had to dismantle the hub to get the sensor out as it was stuck, so i imagine they checked the ABS ring for damage.

Are you any further forward with your problem?