Good evening I've just joined this forum and I'd like some help or advise on the following problem.
I recently replaced my brake Master cylinder and on two occasions since the replacement the 4 wheel disc brakes have applied themselves and the brake peddle was hard and would not move. No warning light illuminated the ABS light is functional and illuminates at start up goes out once the car runs through its start up sequence.
any help would be appreciated
Rhys

 

Did you bench bleed the master? You also need to command the ABS system into bleed mode

 

yes it was done what seems to be the potential problem is in the booster itself. The car will be taken to one of the ABS/Brake service businesses on Tuesday to confirm this or identify if indeed there is an issue in the ABS pump itself

 

I’ve had the same ABS light on my 02 X type and through my personal “travels” and trips down the “rabbit hole” of random things that can go wrong with Jags, I replaced all four wheel speed sensors. Still had the ABS light. I thought maybe that my passenger side rear caliper is frozen and causing the problems. But it didn’t seem to be that after further inspection. I checked my ABS control unit and it doesn’t seem to be that. But then I found a thread somewhere that mentioned checking the Yaw control sensor, which is under the J-Gate/radio/cigar lighter in my X Type. I guess sometimes the sensor can delaminate and malfunction. Yaw control basically sends independent messages to the ABS systems for each wheel, telling them “less” or “more” braking depending on the driving conditions and situations..in order to prevent roll overs. If the sensor is malfunctioning and sending bad signals to the ABS unit it COULD be causing the fault. By no means do I claim to be right about this, but it is definitely something worth looking at. Have your mechanic or whomever check your yaw control. If it is that sensor, you can find them on eBay, new or used, for under a hundred bucks. I’ll tell you, I do all the work on my cat myself, and I’ve gotten nearly all my parts off of eBay. And I’ve never had an issue. Save yourself tons of money.