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Omega General Help / Re: ABS-light constantly on after replacing front ABS/wheel speed sensors
« on: 28 October 2023, 14:02:52 »
Both the frequency AND amplitude of the sensor output will increase with RPM. You say you are measuring at 2 RPM. Assuming you're using 235R45x17 tyres, the rolling circumference is 79.57 inches (2021mm). 2 RPM is 120 revs per hour, which is therefore 9548 inches per hour, which is only 0.15 miles per hour.
I don't think the ABS is supposed to work at all below 5mph. Therefore the voltages you are seeing from the sensors are not representative of what you should see if the car is travelling at > 5MPH (8 Km/h).
Your 50mV at 2RPM might be correct - Try it again at a more realistic 200RPM (15 MPH), you should get a much larger signal - probably 20-50 times larger. Remember the ABS needs to work all the way up to above top speed (say 2000RPM/150MPH) so the signal can be massive at that speed. If you adjusts the sensors to give large signals at very low speeds, then at normal/high speed you can overload the ABS inputs.
I've got some old Carlton hubs in the lockup, still with the ABS sensors fitted. I'll dig them out tomorrow and measure them up for clearance. 0.2-0.3mm sounds way too close to me.
I don't think the ABS is supposed to work at all below 5mph. Therefore the voltages you are seeing from the sensors are not representative of what you should see if the car is travelling at > 5MPH (8 Km/h).
Your 50mV at 2RPM might be correct - Try it again at a more realistic 200RPM (15 MPH), you should get a much larger signal - probably 20-50 times larger. Remember the ABS needs to work all the way up to above top speed (say 2000RPM/150MPH) so the signal can be massive at that speed. If you adjusts the sensors to give large signals at very low speeds, then at normal/high speed you can overload the ABS inputs.
I've got some old Carlton hubs in the lockup, still with the ABS sensors fitted. I'll dig them out tomorrow and measure them up for clearance. 0.2-0.3mm sounds way too close to me.