ABS Sensor comes on over ~60mph

Technical Area Wheels, Tyres & Brakes
1
  1. My model of MX-5 is: 2008 PRHT
  2. I’m based near: Yorkshire
  3. I’m looking for technical help or recommendations on: ABS fault.

Afternoon all,

We had some decent weather so took the NC out for a spin. After about 15 miles I noticed the ABS light was on so pulled over. After turning it off and immediately restarting the light stayed out for a while, but seems to come back on when the car gets above around 60mph. It goes out again after restarting and doesn’t come back on until its gets to about that speed.

I’ve plugged in my cheapish OBD2 scanner but it didn’t find any codes, does anyone have any idea what this could be?

Thanks

2

Have you checked the fluid level in the brake resevoir. Light also acts as low fluid level indicator.

3

Yep, fluid level looks good, not quite at maximum but well above the minimum level. Not sure why it only comes on above a certain speed really?!

4

Could just be fluid sloshing to the rear of the resevoir at speed and float dropping slightly. Top up to full level and see if it stops.

5

Has it one odd tyre, different make to the others?

Our old Vextra when quite new suddenly lit the ABS light after a few minutes at about 70. This after we had to replace a punctured rear tyre for the second time and found the new but different make spare we had bought triggered the problem.

The ratings, size, circumference etc were all identical, except for the rolling resistance. By now the other three tyres had lost a couple of mm of tread, but buying two new tyres of the correct make solved it even though they were not worn.

I took it back to QF and they agreed to refund me for the “Fateo” they had ‘recommended’ and gave me a good discount on the replacement Goodyear Eagles.

6

I don’t think so, they’re all Kumho’s pretty sure the same on all corners. The wheels aren’t the standard for the car (1.8 so it came with the 16" 5 spokes), I got a set of the BBS Z-Sport wheels but they’ve been on since around September with no issues.

Thanks for the idea though. I’m thinking with it being ‘speed related’ it has to be either a wheel or wheel speed sensor issue.

EDIT: That being said, I’ve just checked and they are all 205/45Z R17 88Y, but the front driver and rear passenger are marked as XL where the other 2 aren’t.

7

Well spotted.

Put the XL on the same axle and the other two on the other axle.

That might well fix it!

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