X-Type ABS issue

[Phil Darby]

My 2003 V6, 3L X-Type has a recurring problem that goes away for weeks then comes back, each time being worse than before.

Each time that I apply the brakes the ABS engages. However the dash light doesn't come on (it is functioning). I've had the control unit reconditioned (twice because I wasn't convinced the first time). No faults show on diagnostics (not even if we leave the tester connected and watch when the fault occurs). The sensors and rings have been checked and pronounced OK.

It used to be intermittent in that if I stopped, switched off the ignition and then started again it would often clear. I've also cleared it in the past by connecting the diagnostic tester even though there are no faults showing. If I remove the fuse for the ABS the fault does not occur. It also stopped for a while when I replaced a steering arm and again when I had the tracking adjusted, but it comes back again after a few days weeks.

This is severe in that the pedal engages very high up and braking is slow and pulls to the right when it happens. It is also embarrassing as the ABS makes a ratcheting sound that everyone can hear.

Anybody come across this before? I'm going mad!

 

[cosmicma]

iv'e come across it twice but both on hondas not jags
both times it was a failing ABS wheel sensor 

[JOE-DOT-COM]

HI

Did not think any lights come on the dash for ABS operation, only a fault bring it on and it light up for a few seconds everytime the ignition is switch on, just to proove light works

Only traction control brings a flashing light on, when it operates

cheers

Joe

[cosmicma]

what causes the ABS to kick in when it's not supposed to is the speed signal being interrupted 
not enough to throw a fault up but enough to fool the system into thinking a wheel has locked 
the trouble is because a wheel hasn't actually locked it's hard to determine which sensor is at fault you really need to be looking at live data to see which wheel sensor is causing the problem 
rest assured it will give a fault eventually 
 

[Phil Darby]

Thanks to everyone. I also believe that live data is the key to solving this, but so far it hasn't shown anything, even when the fault occurs when the  diagnostic is connected.

I suspect I'll have to change the rings and sensors to be sure of a solution, regardless that they all check out as OK.

If anyone else has any ideas, I'm all ears!

[cosmicma]

live data should show whats going on 
if you can record the data that would be even better