Posted by Peter Holland on September 29, 2009, 1:45 pm
Customer complains that when the vehicle is on full lock, the ABS cuts in under braking. Its a long wheel base, rear wheel drive Transit. No fault codes stored. Another garage has fitted a new n/s/f speed sensor. Live data shows a signal from all four wheels and I've scoped all wheels as well. There appears to be no signal drop out under hard cornering etc.
I've checked that all the tyres are the same size, checked for play in the wheel bearings etc. The only thing I've noticed is there is about 2mm play in the half shafts, which I'm led to believe is not unusual for Transits. Has anyone had any experience of this and would the play in the half shafts be enough to reduce the output voltage of the ABS sensor. I can't see a noticeable difference on the scope, but at the low speeds needed to induce this fault, the output voltages are pretty small anyway.