I keep getting the ABS light come on fairly regularly. I have cleared the fault code (12), but the fault seems to return almost straight away. My understanding is that this is a faulty front passenger side sensor. I have tested this with a multimeter and it seems to show it is still ok, as I get a reading of 1.4k ohms.
Any ideas what this could be ?
What model MX-5 is it? NA wheel speed sensor resistance should be 1.1 kilo ohms and code 12 could also point to a damaged ABS ring, the part the sensor picks up from. NB F/L sensors should be 1.0 - 2.0 kilo ohms.
It could be a break in the wire between the sensor and the ABS control module. When you say the fault returns almost straight away do you mean as soon as you drive off? To confirm that it is or isn’t the wheel speed sensor you could use lengths of wire and connect the RH sensor to the LH harness and the LH sensor to the RH harness and see if the fault code changes to point at a fault with the other sensor. Don’t drive the car any distance with the ABS sensors crossed over though.
Re the resistance reading, I had a sensor that gave a good resistance reading, but on connecting to an oscilloscope it did not produce a waveform when the wheel was rotated. The sensor was duff, changing it cured the problem.
Yes, it is rare for it to be anything other than a faulty sensor.
Thanks All. The car is a NB model, so resistance checks out ok. I cleared the fault code and started the engine with no ABS light showing, but whilst the car was warming up (about 3 minutes later) the fault light reappeared.This was before I even put it in gear to move off.
I have since checked the fault codes again, and I now have fault code 11 and 12 showing !!!
I have since taken both wheels off and noticed that the ring and sensor were filthy, which I have now cleaned up. The rings were both fine with no damage showing.
I started the car last night and no ABS fault was showing at standstill, although I have not driven it yet. I will do that today to double check the fault has gone.
If the fault returns without the wheels rotating it won’t be an ABS ring issue.
Further update. I have taken the car for a drive this morning and I have had no ABS light come on. However I rechecked for fault codes and fault code 12 came up, even though the ABS light did not come on whilst driving the car, and is currently not remaining on ??
I have cleared this code again, but wondered if I have some other fault, or the original ABS fault will reappear shortly ??