Rear Caliper Binding - Seat Toledo MK2 2002 1.9 TDI

[barrymurphy]

Hello,

I have an issue where the rear passenger brake will start to engage and bind when driving after pressing the brakes a few times.

So this evening I pulled the fuse from the ABS as I was confident that the calipers were fine and I replaced the line on saturday.

Voila, the issue is gone and the rear passenger no longer locks.

I stopped the car and replaced the ABS fuse and slowly the issue returns after pressing the brakes lightly a few times. Then when it starts happening and you slow the car to very slow it starts trying to bind harder and will bring the car to a stop. You can drive on if you accelerate as the brakes on the other three wheels are not on. But it is trying its hardest to stop you.

So the question is - is this the abs wheel sensor and if so would this tell the abs to lock one wheel or would it try to engage on all 4 wheels or.....

is this air in the abs module causing the locking of one wheel?

I say air in the abs as I recently changed the master cylinder but this only started happening a few weeks after the master cylinder change and everything has been fine until now since the change.

So have I answered my own question? it is the sensor? but would the abs module try to lock one wheel only?


Barry

 

[Burnerman]

Although it's very rare, some faults in the ABS module can cause brake misbehaviour including locking up.....however with faults like this the brake pedal feels very hard i.e as if the servo isn't actually doing anything.
A couple of actions to consider: (Assuming that the brake system has absolutely no air in it, of course!)
1) Take the car to a garage that can do ABS module interrogation
2) Contact BBA-Reman by phone to hear if they know anything about this problem. They can remanufacture your ABS module if necessary.
I wouldn't randomly chuck parts at the car at this stage!
John

 

[Harry Bloomfield]

It sounds like a sticking valve in the ABS modulator unit - the unit where all of the brake pipe meet up. It should record an ABS fault, if you can find a garage with equipment to diagnose the ABS.

 

[barrymurphy]

Thanks.

The pedal does not feel very hard.

Would the abs module behaviour affect one wheel only?

The pedal feels normal and gradually gets hard after a while using the brakes but it gets hard because one caliper is locked on.

Thanks

Barry

 

[barrymurphy]

Hi thanks,

Another thing, the ABS light is not on and when I use the ABS brakes they work perfectly. I went to an industrial estate, gathered speed and slammed then on. They worked very well. I did this a few times.

Surely a sticking valve would affect performance and/or the ABS light?

Barry

 

[barrymurphy]

UPDATE

The brakes worked well but there was binding on one wheel but there was another issue where no fluid would flow to the rears when bleeding, (fluid would come out when the pedal pressed but not of its own accord), and indeed when you disconnected the two pipes coming from the MC to the ABS there was no fluid flowing from them either (again would flow when pedal pressed). The binding could still have been an ABS issue as it affected only one wheel? Or could it have been a return issue where fluid is not allowed return properly after the pedal is released but I read somewhere that this would have affected at least two wheels and not one?

Anyhow, I found the cause of the non flow. The bottom bolt on the MC was too tight against the servo and so pushing the piston in a fraction too much. As soon as I loosened it just a bit fluid started flowing. So one issue resolved.
I also removed the ABS and used compressed air and brake cleaner through the ports to blow out any crud and clean the valves.

I am hoping this will be my problem resolved but will not know until tomorrow.

My question is whether the problem at the MC could cause the binding at one wheel or did I indeed have two separate issues?

Barry