My abs. light comes on my renault megane whenever

HALLO

CHECK REAR HUBS IF THEY RE FOR ABS TYP. IF THEY HAVE ABS RING INSTALED. ALSO CHECK DIMENSIONS OF ALL FOUR TYRES. SHOULD BE THE SAME. LIGHT COME ON BECOUSE OF DIFERENCE BETWIN WHELL SPEEDS- CONSTANT.

MARKO

If the tyres are different diameter the number of pulses per revolution will only be small and ignored at slow speeds. If it counts for 5 seconds and check that all sensors are the same, at slower speeds the number of pulses may all be within tolerence. Once you go fast enough, you will get more pulses in the same time period, so a larger tire would give many more pulses than a smaller one and flag up the error. It is worth making sure the ABS rings are clear of brake dust and rubbish when doing any brake work, as it may hide damaged or missing teeth on the ABS rings, etc.