Hi all great site, I have a problem on my fiat 500 t/a Dualogic . When at standstill brake pedal works fine but when driving I am forever having to lift the pedal back up with my other foot after brakes are depressed. The brakes are dragging but when pedal is lifted it feels fine this is throwing transmission errors, hill holder asr faults all over the dash I have scanned the car and got c0037-29 speed sensor psx invalid signal , p0856-81 bam gearshift invalid data I have changed brake switch twice cleaned wires removed battery cleaned all contacts and wd40’d done all earth points new pads n discs on front cleaned callipers and still none the wiser please help I’m at my wits end ?
Technical Fiat 500 brake problems driving me mad ?
- Thread starter Jayhay79
- Start date
Currently reading:
Technical Fiat 500 brake problems driving me mad ?
Sounds like just a mechanical issue with the pedal - servo..
The errors would probably not flag on a manual..
The errors would probably not flag on a manual..
Try, go under the dash WD40 on the pivot points on the brake pedal, move it by hand to see if it moves freely and more to the point returns to it's resting position ?
Also check the arm that goes across the car for obstructions like say mats etc.
Also check the arm that goes across the car for obstructions like say mats etc.
Last edited:
I had this with one of my earlier cars. It actually seized the brakes on, when on my first drive to work after repairing it. I had to call the AA after nearly burning the clutch out. While waiting for recovery, something just told me to try it after sitting there for about 45 minutes. It drove fine. The recovery arrived and I told him it seemed OK, so he followed me home and it was fine all the way.
The following day, I noticed that it was exactly as you describe. I had a look underneath at the pedals, put grease on the pivot which I thought it probably was, didn't make any difference. I ended up changing the pads and it went away. It was weird, not really ever got to the bottom of what caused it but changing the pads did the job.
The following day, I noticed that it was exactly as you describe. I had a look underneath at the pedals, put grease on the pivot which I thought it probably was, didn't make any difference. I ended up changing the pads and it went away. It was weird, not really ever got to the bottom of what caused it but changing the pads did the job.
I changed pads and discs about 4 months ago it went away for a while now has come back worse checked all the bar and still stumped ?
If the pedal is not coming back then that sounds like a master cylinder problem, although if the brakes are binding then that might be causing the master cylinder problem.
So, first job for you is to identify which/if any of the individual brake calipers are sticking when you have pressed the pedal and released it. When your pedal is stuck at "mushy", jack up each side of the car in turn and test which wheel(s) are still being braked.
If changing the pads solved the same problem a few months ago then that suggests the pads you are using could be jammed in the calipers. Take the caliper off (each of the front wheels) and check to see that the pads are free. They should be able to just drop out.
If they are stiff or stuck in the caliper frame then that's the problem. Take them out and clean the slots where they fit. You may need to file the pad "ears" .. since they rust and can expand. The pads should be fairly "loose" (but not rattly) in their seats. Cheap pads are worse for this. Buy some Brembo and feel the difference.
If the pads look okay but one wheel is still being braked, then it could be the rubber hose has degraded and is causing an internal lock. If it goes away after a few hours sitting on the driveway, then this could be a contender. The only solution is to replace the hose.
I presume you have drum brakes on the rear, in which case it's the front that is most likely to be the problem so start there first (unless your rear shoes are sticking/getting so hot that they're smoking, etc.) If you have discs all round, then the problem could also be at the rear... but the fronts are the most likely, given your rather severe symptoms.
Ralf S.
So, first job for you is to identify which/if any of the individual brake calipers are sticking when you have pressed the pedal and released it. When your pedal is stuck at "mushy", jack up each side of the car in turn and test which wheel(s) are still being braked.
If changing the pads solved the same problem a few months ago then that suggests the pads you are using could be jammed in the calipers. Take the caliper off (each of the front wheels) and check to see that the pads are free. They should be able to just drop out.
If they are stiff or stuck in the caliper frame then that's the problem. Take them out and clean the slots where they fit. You may need to file the pad "ears" .. since they rust and can expand. The pads should be fairly "loose" (but not rattly) in their seats. Cheap pads are worse for this. Buy some Brembo and feel the difference.
If the pads look okay but one wheel is still being braked, then it could be the rubber hose has degraded and is causing an internal lock. If it goes away after a few hours sitting on the driveway, then this could be a contender. The only solution is to replace the hose.
I presume you have drum brakes on the rear, in which case it's the front that is most likely to be the problem so start there first (unless your rear shoes are sticking/getting so hot that they're smoking, etc.) If you have discs all round, then the problem could also be at the rear... but the fronts are the most likely, given your rather severe symptoms.
Ralf S.
Last edited:
Sounds like something binding
That will generate heat
Once its done its 20+ drive..and is showing the fault..
CAREFULLY go around the 4 wheels.. looking for differences in temperature.
1st lightly touch the wheel itself
Then put your palm near the centre of wheel
If still feels cold..
Put a finger tip on the wheel nut hexagon.
Anything rubbing will soon warm the area.. so beware of HOT surfaces.
If its REALLY HOT you will probably smell it.. and save your finger tips
Charlie
Make sure the backs of the pads are well greased up with copper grease too.
The brake pedal should have a spring on it to bring it back up, even if the master cylinder does not follow it. So this suggests that the problem is with the pedal or the linkage across the car.
You need to spend some time under the dash, upside down with the blood rushing to your head, and you'll feel dizzy when you get out. Lovely job.
You need to check the pedal pivot, and the linkage across the car, as the servo and master cylinder are on the left. Make sure nothing is in the passenger footwell causing problems. (Some time ago someone posted about a similar problem, which was caused by their passenger sticking their feet against the linkage. Only had the fault when carrying that passenger.)
Another issue could be the brake light switch. This has caused problems on other models too, particularly Stilo I think. When fitting a new switch, there is a procedure to 'set' it correctly. If disturbed, or occasionally it just seems to reset itself, it can be incorrect, and will hold the pedal down a little. Driving without the switch might help a diagnosis, but brings a high risk of being hit from behind, so not a good idea unless you can find a very quiet road.
When the problem occurs, ideally you need to stop and grovel under the dash to see why, checking switch, and linkage, etc. Might need a test route with thought to allow safe stopping points.
Do a search for brake light switch. Somewhere there is a nice procedure for resetting an old one. (Might be in another model thread, perhaps Stilo.) Fiat say if disturbed, must be replaced with new, as they come ready for an initial set. But occasionally new ones have 'let go' so need resetting anyway.
You need to spend some time under the dash, upside down with the blood rushing to your head, and you'll feel dizzy when you get out. Lovely job.
You need to check the pedal pivot, and the linkage across the car, as the servo and master cylinder are on the left. Make sure nothing is in the passenger footwell causing problems. (Some time ago someone posted about a similar problem, which was caused by their passenger sticking their feet against the linkage. Only had the fault when carrying that passenger.)
Another issue could be the brake light switch. This has caused problems on other models too, particularly Stilo I think. When fitting a new switch, there is a procedure to 'set' it correctly. If disturbed, or occasionally it just seems to reset itself, it can be incorrect, and will hold the pedal down a little. Driving without the switch might help a diagnosis, but brings a high risk of being hit from behind, so not a good idea unless you can find a very quiet road.
When the problem occurs, ideally you need to stop and grovel under the dash to see why, checking switch, and linkage, etc. Might need a test route with thought to allow safe stopping points.
Do a search for brake light switch. Somewhere there is a nice procedure for resetting an old one. (Might be in another model thread, perhaps Stilo.) Fiat say if disturbed, must be replaced with new, as they come ready for an initial set. But occasionally new ones have 'let go' so need resetting anyway.
Hi thanks for all reply’s I’m stumped I’ve cleaned front callipers all fine stripped under dash to see all components greased and wd40 all joints look fine I changed servo vacuum pipe and still not working. The pedal works flawlessly when idle or engine off but put it in drive and the brake pedal does not come back would this be Dualogic issues or vacuum issues?
Sorry was a quick reply? I’ve spent prob 15-20 hrs trying everything without a fiat specialist around here?
Hi I cannot find a spring or an area for a spring to go ? I’ve studied under the dash and all literature I can find but cannot see anywhere one would go?
Is this still reliant on 20 mins?
Is it binding brakes ? ( you havent said about which hubs get hot..)
Please explain more thoroughly
If we are to help.. we need the whole picture
Is it binding brakes ? ( you havent said about which hubs get hot..)
Please explain more thoroughly
If we are to help.. we need the whole picture
Is this still reliant on 20 mins?
Is it binding brakes ? ( you havent said about which hubs get hot..)
Please explain more thoroughly
If we are to help.. we need the whole picture
Hi sorry it’s now doing it from start up I’ve checked the brakes none are binding had on 2 post ramp all wheels are free as long as the brake pedal is pulled up in the car. When the pedal stays down both fronts pull it takes no pressure just a flick to bring pedal up. I have removed brake servo pipe and taken for a drive and the pedal comes up on its own albeit the pedal you have to push harder to get the brakes to work wether that’s because you have to push harder. it’s a full brembo set up on the front pads and discs replaced 6 months ago. It seems 90% of the time if you feather the pedal rather than stab it stays down if you stab it it comes straight up on standstill but not when driving. If you pump the pedal it’s hard then start up it sinks 1/2” as it should but once in drive it’s staying 1/2” down once pushed which throws the gearbox fault? I have disconnected the brake booster on the engine and that is sucking air and throws the engine light on when running I changed the servo pipe with the sensor on but that’s not altered the issue
The servo has a valve inside that allows air to bleed to provide the assistance. Many years ago these could become sticky, but I've not heard of one recently, so possible, but unlikely.
The master cylinder could be sticky, if the seals are failing.
Being RHD, there is a linkage across the car, with several pivots, any of which could cause this issue. The brake light switch is also a possibility.
To determine the problem, you have to get under the dash and check every possibility. This means probably disconnecting each part and checking if it is tight, or free.
Start by removing the brake light switch and checking operation. If the pedal now returns, you need a new switch. Don't drive it like this, as you have either no brake lights, or they're on all the time.
If switch not the issue, disconnect the linkage from the servo, this is under the passenger side dash. Note where the servo pushrod is, push it, and allow it to return. Does it return fully? If it returns fully several times, servo and master cylinder are ok. If it does not return, you need to disconnect the master cylinder from the servo to determine which of the two is the problem.
With the linkage disconnected, is it free? May need to dismantle some or all of the pivots.
Attached is a file from the Panda workshop manual, showing a spring around the brake pedal pivot shaft. Can't see it listed on the parts listing for 500.
I'd still put a shilling on the switch.
The master cylinder could be sticky, if the seals are failing.
Being RHD, there is a linkage across the car, with several pivots, any of which could cause this issue. The brake light switch is also a possibility.
To determine the problem, you have to get under the dash and check every possibility. This means probably disconnecting each part and checking if it is tight, or free.
Start by removing the brake light switch and checking operation. If the pedal now returns, you need a new switch. Don't drive it like this, as you have either no brake lights, or they're on all the time.
If switch not the issue, disconnect the linkage from the servo, this is under the passenger side dash. Note where the servo pushrod is, push it, and allow it to return. Does it return fully? If it returns fully several times, servo and master cylinder are ok. If it does not return, you need to disconnect the master cylinder from the servo to determine which of the two is the problem.
With the linkage disconnected, is it free? May need to dismantle some or all of the pivots.
Attached is a file from the Panda workshop manual, showing a spring around the brake pedal pivot shaft. Can't see it listed on the parts listing for 500.
I'd still put a shilling on the switch.
Thanks all for suggestions on this problem I changed air servo pipe then next day at work plugged car in reset all faults and voila problem solved ??? after many weeks of issues the problem is cured also done all earth points lubed brake mechanisms cleaned callipers. Had mot today car on rollers for brake test and all pulling and releasing as they should. Thank you again for all your help it’s great to know a community page like this exists
