east to test sensors with a meter if open circuit they are nbg, but that should also put abs light on all the time, so I suspect that maybe cleaning the face of all sensors and greasing the toothed wheel inside the hole after removing sensor may help, best of luck as can be troublesome to sort out. also the fluid level will trigger warning lamp, maybe fluid a bit low and when driving the fluid moves in master cylinder and alerts the system and then triggers the light, worth checking before taking everything apart. If all else fails the circuit diagram would help but I only have the one for a 2wd.