[blackterminal]

Random question. If you have your car conversion on jack stands and you are testing with wheels off the ground ABS light goes on?

I was testing using my original throttle cable last night on my BMW project and my abs light went on. Wheels up off the ground. The only thing I can think of is when I briefly held onto one of the spinning rear wheels and the diff then rotated the other side. I didnt think that would be a problem but soon after that the ABS light went on and stayed on. Is that normal?

 

[remy_martian]

A human holding on to a spinning rear wheel looks like a brake is being applied with no brake line pressure sensor indication and is not not normal.

 

[Duncan]

The traction control and the ABS operate by measuring the acceleration of the wheels
If the car is on stands with the wheels in the air then they will accelerate (and decelerate) much much faster than if they are having to accelerate the whole car

 

[VintageVolts]

Yes our (BMW) Mini used to throw ABS faults in addition to the low tyre warning light if one of the tyres was a bit flat, to reset it we were told to drive it in a figure 8 pattern in an empty car park - this then allows the steering position sensor to reclaibrate with what the wheels are doing.

I guess the non-powered wheels are expected to turn roughly the same RPM as the drive wheels, if no signal comes back then the control unit suspects it's faulty. Just a guess!