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Technical My Punto Mk2 Brake Problems

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Technical My Punto Mk2 Brake Problems

peaster2k

peaster2k

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Well, its driving me up the wall. Two problems that might be related or not.

1. The ABS will kick in at low speed (under 20mph) at the small of touches on the pedal, not every time the pedal is pressed though. At first I thought it would be the rear bearings/hubs as I discovered the handbrake lever had been rubbing on the hub. After replacing them both the problem still persists, so I decided to move onto the front.

I expected (well hoped) to find a broken ABS ring on the outer CV joint but after initial investigations I am proved wrong - see photos - as it doesn't have an ABS ring. I assume this is correct as its a magnetic sensor?

2011-11-26115003.jpg

2011-11-26114945.jpg

2011-11-26114912.jpg


I've checked the error codes in the ECU and no sensor fault is being reported.

2. The car pulls to the left under heavy braking, mainly down a slip road. Its been on the rollers and the left front and right right rear are pulling more than the right front and left rear. The rear operates fine under the handbrake.

The car is a 1.2 16v Sporting Mk2 X Reg (2001).

Its had new discs/pads/shoes and drums this year, also a rebuilt pair of calipers.

Can anyone suggest what to look at next or what the problem might be?
 
Asymmetric braking effort could be the cause of the ABS kicking in. It looks at differences between wheels. With my optimistic hat on I would hope a fluid change and flush would sort it. If the rebuilt caliper is not pulling it's weight , say front right , that might also be enough to provoke the ABS.
 
Brendan W said:
Asymmetric braking effort could be the cause of the ABS kicking in. It looks at differences between wheels. With my optimistic hat on I would hope a fluid change and flush would sort it. If the rebuilt caliper is not pulling it's weight , say front right , that might also be enough to provoke the ABS.
Click to expand...

Thanks Brendan, I had started to think along these lines before. Although in saying that the two problems started at different times, brake imbalance was present at MOT time and the ABS problem didn't start until a few months after. But a bleed of the full system certainly won't go a miss.

I've been doing some more digging, surely I should be working, and think that I've came to the conclusion that the sensor on the front picks up the signal from the back of the wheel bearing. This may or may not be at fault, not sure how I establish which side is at fault though.
 
you might have a restricted brake hose causing brake inbalance especially at this age
the abs pickup does indeed collect its signal from the back of the hub bearing ,maybe its dirty /well corroded/ or a combination of both these things
a proper diagnostic test should point towards the problem wheel but have to admit i dont know what machine would do it as fortunately ive never had your problem
 
On mature reflection you said that both right front and left rear are lazy. This would make me inclined to suspect the master cylinder in the absence of a large leak. I don't know about the internal plumbing in the ABS but, as it can control wheels individually, the underlying fault is most likely upstream of the ABS.
 
s and b said:
you might have a restricted brake hose causing brake inbalance especially at this age
the abs pickup does indeed collect its signal from the back of the hub bearing ,maybe its dirty /well corroded/ or a combination of both these things
a proper diagnostic test should point towards the problem wheel but have to admit i dont know what machine would do it as fortunately ive never had your problem
Click to expand...

I read about this, both fronts have been replaced not that long ago as they had been rubbing.

Brendan W said:
On mature reflection you said that both right front and left rear are lazy. This would make me inclined to suspect the master cylinder in the absence of a large leak. I don't know about the internal plumbing in the ABS but, as it can control wheels individually, the underlying fault is most likely upstream of the ABS.
Click to expand...

Another thing I'd thought about as its a split system. When you say upstream of the ABS, do you mean the lines between the master cylinder and the ABS pump?

My next step has to be to double check all the pipe work for leaks and bleed the system in order. Then take it from there.
 
Last edited:
I've had a look at the pipe work between the master cylinder and the abs pump; I can't see any obvious leaks. As you would expect I've got two pipes (one for the RR/LF & another for RF/LR). What I can't tell is which one is which at the master cylinder end, does anyone know?

2011-11-29131912.jpg
 
Did you find a solution to this problem, my wifes Punto has the same problem, I have noticed though that sometimes the ABS light comes on and when it comes on the grating sound stops.

Thanks in advance

Mark
 
mncollyer said:
Did you find a solution to this problem, my wifes Punto has the same problem, I have noticed though that sometimes the ABS light comes on and when it comes on the grating sound stops.

Thanks in advance

Mark
Click to expand...

grating sound mite be a wheel bearing, jack it up spin the wheels and check for the grateing sound.
 
Going in on Tuesday to be looked at, was just looking for info to pass on to him. He thinks it is something to do with ABS but has got to strip out driveshafts for access to sensors. Will post back with findings.

Mark
 
mncollyer said:
Going in on Tuesday to be looked at, was just looking for info to pass on to him. He thinks it is something to do with ABS but has got to strip out driveshafts for access to sensors. Will post back with findings.

Mark
Click to expand...

there isnt an abs ring type pickup on the punto
driveshaft
therefore if he thinks theres an error its the pickup connector which i have successfully removed by duck oiling having a cuppa then returning to and with proper fitting mole grips very slowly wiggled side to side to clear the rust build up in the hub hole before withdrawing to replace with another free s/h one from the scrappies

he still needs to check pads

ideally a fault code reader like the sykes pickavent with appropiate fiat pod would be ideal because i dont think the fiatecuscan lead can give abs sensor readouts? (anybody?)
 
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