ABS Warning Light - Intermittent
 

Puzzled by intermittent ABS warning light.
Sometimes it knocks the speedo out, sometimes not.

Checked continuity of wiring between sensor on front right wheel and all seems OK. I was about to order a front right sensor, when the ABS light came on and the speedo was still functioning.

Normal braking function is retained, no crunching on slow speed braking, so all reluctor rings seem OK.

Any clues on what to look for first, before replacing anything?

Car is an MGZT-T 2005 - had from new

Possible breaking down with moisture at the connector above the Arch liner?

John, Thanks for the response - you mean the blue connector on the front right sensor, clipped into the top of the front right wheel arch, immediately under the bonnet?

I disconnected this and checked it and reconnected it, when I was checking the wire on the front sensor for breakages - it seemed pretty dry.

I guess the main puzzle here is that it seems unlikely that the ABS fault is only attributable to the front right wheel sensor, otherwise wouldn't it knock the speedo out every time?

Sometimes the ABS warning light comes on and the speedo is still in tact.

Or did you have another connector in mind?

Larry

Check the Plug and socket on the ABS unit under the Battery box. not easy to get at but it is very vulnerable to wet and spray, particularly driving through puddles! see my posts at https://www.the75andztclub.co.uk/for...d.php?t=247845

Hope this helps

Thanks Chuck, I did this once before and it was dry as a bone. This was a couple of years ago when I had a low speed crunch ABS symptom which turned out to be a rear hub after I did all the meter pulse tests on each wheel.

I even cleaned every pin on that plug before reassembling the whole battery compartment - agreed it's a tough one to get to.

As the car is garaged and it's 13 years old I'm pretty confident the plug will be as dry as a bone like last time.

I'm still thinking it must be a wiring chafing or failing sensor, it just puzzles me that sometimes it affects the speedo and sometimes it doesn't and also it often clears itself when you turn off the ignition and then turn it back on again, so the system either does or does not pass the initial self test procedure.

Anyone else seen a similar pattern of speedo affected and then not, in a somewhat arbitrary or intermittent manner?

I'm going to try a new sensor on the front right wheel, anyone have a link that will take me to an original sensor for front wheels?

LR

Ok - Long break, been away.
Ordered a new ABS Front sensor and decided to change the one on the front drivers side wheel as the intermittent fault invariably knocked out the speedo, so assumed that something was wrong on that wheel.

I took out the old one, without too much trouble, but notice it was covered in rust and I then started pulling out as much loose and what looked like damp rust from the sensor channel, using a soft cloth.

I fitted the new sensor, connected up and all seems Ok on driving for a couple of miles - need to try it for a week or so to see if the problem comes back - touch wood.

Anyone else experienced such a rusty situation and know whether this could cause this kind of intermittent fault?

It may be that the old sensor is still OK, but I put the new on in anyhow and will keep the other one in reserve.

Larry