MX5 Mk3, wheel bearing replaced now ABS light on. HELP!

[Rubin215]

Hi Folks, looking for some help/advice.

Last night I helped a friend replace the n/s front hub on his 2007 Mk3 MX5.

All went smoothly, no big hitting things or swearing required to get the old one off, and the new one went on without a hitch.

Everything is back in place, including the ABS sensor, BUT now the ABS light is on and won't go off.

What have we done, and how do we cure it?

Thanks for any advice.

[devnull]

The light is probably staying on due to a connection not being made properly, it might be the wrong sesor, it might be faulty, etc. You might also want to try unplugging battery for 10 mins to clear any fault codes?

I know you can read the codes for ABS on a MK2 MX5, but not so sure about the MK3. Ask on the MX5oc.co.uk forum or MX5nutz.

[miniman]

How far have you driven it since the work? Presume the reluctor ring is present?

Edited by miniman on Sunday 1st July 11:33

[Superhoop]

MkIII doesn't have a reluctor ring, the ABS sensor picks up its signal from a magnetic ring built into the wheel bearing.

Was it a pattern part or genuine Mazda? If non genuine, does it have the magntic pick up built into the bearing?

[TooLateForAName]

Is the sensor in properly?

Some vehicles have a plastic sleve/spacer that you replace when you disturb the sensor - makes sure that the spacing between the sensor and the reluctor is correct

[Schuey M]

Take it out for a few miles and it may reset itself.

[morgrp]

Have you cracked the abs ring fitting the new bearing?

[Rubin215]

So after taking the sensor out again last night, it had tiny flakes of rust on it; I can only assume they came from the old hub.

Cleaned them off and replaced it and now it has stepped down to an intermittent fault; sometimes the ABS light goes on when driving, but then goes off again soon after.

Bloody electronics...

[Rubin215]

So, after a two month holiday (no, seriously) he finally took the car to a Mazda dealer who hooked it up to the diagnostics and pronounced that the abs sensor was goosed.

They replaced it.

The light stayed on.

They then diagnosed that the new hub must be faulty.

They still charged him for the new sensor plus half an hour labour (just over £100 in total) but waived the diagnostics fee as a "good-will" measure!

Tomorrow, we fit new hub no.2

[Rubin215]

Gaaaaah!!!

New hub No.2 does exactly the same thing as new hub No.1!!!

Start the engine up and pull away, the ABS light goes out.
Accelerate to 10mph and it comes back on and stays on.
Turn off and start again and it does exactly the same time and time again.

Over two hours we tried all combinations: new sensor old hub, old sensor old hub, new sensor new hub, old sensor new hub: all exactly the same result.

What else could be wrong?

[Rubin215]

So now Mr Mazda says that if he takes the car in tomorrow he will re-set the ECU and remove any stored faults.

Why couldn't he do that first time round then...?