Brake Switch problems

[pgainf]

Greetings!

My car is a Panda Multijet 2004 and when I have the brake switch installed the car is always braking a bit.
I notice the car less willing to go.
I already changed the switch 3 times.

Any ideas?
The stop lights work good.

The brake pads, discs, brake fluid, brake tubes all were changed not long ago to try to fix this problem.

Without the brake switch the car works well.
When the brake switch is installed I notice also the pedal to be a bit more hard and up.

My regards

 

[Most Easterly Pandas]

Any ideas?
The stop lights work good.

In which case as harsh as this sounds its likely to be in your head then.

If the brake lights are switching off then there won't be a feed going to the ECU telling it the car is braking which is the only time it should impact on the car.

 

[portland_bill]

When the pedal is released, there should be some free play before the brakes are applied, during this movement the brake lights come on.
If the switch is holding the brakes on, its either the wrong switch, or needs adjusting.
If its not holding the brakes on, as noted above, check the brake lights are actually off.

 

[pgainf]

Greetings!

I wish it was only my imagination but when the brakes start smelling burn a lot it proves it is not.

The stop lights work ok.

The switchs were always bought at Fiat with the car chassis number.

The problems is something in the ECU.

It seems the brakes send some signal to the ECU to cut fuel and or to the ABS ECU.

I have a eml reader and no errors.

Without the switch on the car behaves great.

Probably some electric gremlin is sending brake signals to the ABS ECU.
I tried already to run the car without the abs fuse on and it does the same.

This problem already gave headaches to several mechanics/ electricians.
No one knows how to fix it.
If I go to Fiat they just start changing parts/ECUs and the bill will be more than the value of the car.

My regards

ps.Some guy with the same problem. My car did this before I changed many parts.
http://www.honestjohn.co.uk/forum/post/index.htm?t=94411#m1040137

 

[Most Easterly Pandas]

Without the switch on the car behaves great.

Can you expand, without the switch physically in position or without it plugged into the wiring

 

[pgainf]

This is the most mind troubling fact.

The car only behaves well without the switch physically in position.
It is not really the wiring.

It took me months to detect that.
Never before a car took so much of my sleep away as this one.

My regards

 

[sludgeguts]

I had this exact same problem many years ago - albeit on a Uno.

The plunger went into a threaded tube in the top of the switch.
The threaded tube had two nuts screwed on to hold it in place.
for whatever strange reason, the switch managed to work its way upwards towards the pedal.
Even though the plunger was only touching the pedal marginally, it was enough to close the gap normally left by the pads - but not enough to put the brake lights on.
Cost me a fortune in new brake parts until I finally got the answer from a guy off a forum in America who had the same fault with his panda!

I had to slacken off the top nut to allow the switch to drop further away from the pedal then tighten the bottom nut.
As portland_bill says, there should be some free play before the pedal touches the switch.

When installing a new switch, don't assume that the bottom nut has to stay locked down to the bottom of the thread - against the body of the switch.

If your switch is the 'twist & lock' type - then it maybe that you didn't install it correctly - some switches require you to push the plunger fully in & kinda lock it in place before installing it. As you twist the switch into position, it releases the plunger to the correct position.

 

[portland_bill]

Just looked on Elearn. Procedure to replace switch looks very simple, just disconnect connector, twist and remove. To replace, put in place and twist to lock, reconnect.

Seems foolproof, but obviously something else is wrong.

Just realised that Elearn only shows LHD. Ours is different as we have a complicated linkage to move the pedal to the right, while leaving the servo and master cylinder on the left. So switch is on the passenger side.

Haynes:
Depress the brake pedal and hold it in this position.
Insert the switch into its mounting bracket. Rotate the switch clockwise until the locating lug is felt to engage in its recess.
Release the brake pedal and allow it to rest against the switch plunger - this adjusts the position of the switch body inside the bush.
Reconnect the wiring connector.

Hopefully something there will make you go "OH" and an easy fix from there.

New Haynes manual highly recommended. Find on Amazon or Ebay for good price.

 

[sludgeguts]

Sounds like the switch on my lad's polo, on his you have to 'prime' the plunger first. Iirc, 'something' is on a ratchet & when you locate the switch body, you have to be careful about releasing the pedal so as to allow the switch to set itself. If you mess it up, you have to go through the whole rigmarole again!

 

[pgainf]

Can you expand, without the switch physically in position or without it plugged into the wiring

Greetings!

The post above really made me think.

And the Uno experience by Sludgeguts.

Months ago I already tried to trim the tip of a the brake switch.
Cut too much and the spring inside broke.
So never thought much about that idea again.
The concept of trimming Original parts, didn't seem right to me before.

I read that some people were pulling the tip when it got stuck in, on other Fiat car Models, like the Stilo.

But I didn't think of it to be possible with it in place (out no point because it would get pushed in, the moment I put it in place).
It was already too difficult just to insert the switch on the brake pedal socket. And doing this gave me headaches.

So following your advice and ideas I trimmed the tip of the brake.
This time I tried not to cut into the hollow part of the tip, to not cut the spring inside.
Then used a file tool to trim it until I could see the spring inside the tip, with only +-1 mm left to reach it.

The car now behaves good.
I don't feel any braking at any speed.

This problem was tormenting me for 23 months already, since I bought the car.

Brake lights work good all the time.

Any person with this problem, just be careful and have the tip pulled out. It should be +- 1 cm in size. If it is only 4 mm the brake light will be always on. Use a Plier to pull it out.

This is the brake switch. Many fiat models use the same.

For now it is working good!
The fuel consumption info on the on board computer is still a bit (15%) higher than usual.
I'm still testing it.

But if I sold the car now, no one would notice anything.
Before the car would smell brake pads burn all the time, and less willing to go. The feeling was sometimes like driving with the hand brake on.
I had to drive without the brake switch on to have a normal driving experience.
I would only use it when I went to the 'MOT' like car inspection test and when I was testing.
But a sad feeling was always in me because if I ever wanted to sell the car, I would have to charge little, and wait for phone calls after.

Thanks for ALL YOUR HELP!
My regards!

 

[portland_bill]

I've read the whole postings again and cannot see where you go the idea to trim the actual switch. This does not seem a good idea. The system should work with standard parts. Trimming the switch is an attempt to address the symptoms rather than fix the cause. The switch will also be weaker and may fail.

My advice would be to replace this switch with a new one sometime and follow the instructions on fitting and setting. Good luck with the current setup.

 

[pgainf]

Greetings!

I did bought the switch 3 times.
And they were installed by decades plus professionals.
After they throw down the towel I came to forums to try to find a way out of this problem.
I would call the auto repair shops and they would not even answer my calls...
I even presented the problem to a friend who is a very experienced mechanical electrician. His job is to fix huge cranes and heavy machinery and the diagnostic was the usual... Sell that problematic Fiat.

Before I thought it was a costly ABS ECU problem.
But when some user asked me if the problem would happen when the brake switch was inserted but not connected to the electronic plug, it made me think of all the testing I already had done. Then I tried a new solution and it is working now.

I repeat: I drove the car for more than an year without the brake switch installed and no problem what so ever!
The fuel consumption is super!
Without the switch installed, with some city driving - 76 imperial mpg (3.7 lt/100km)
Without the switch installed, during trips - 85 imperial mpg (3.3 lt/100km)
With the brake switch installed before it was trimmed - 54 imperial mpg (5.2 lt/100km)

The brake switch trimming is a procedure very common in many forums posts from Stilo drivers and etc (usually to fix the 'always on brake lights' problem). I tried it before but broke the switch. This time I was more careful and success!

My regards

ps. If you have any more ideas they are welcome.
At Fiat they pretended they never saw the problem before and when I talked about the Stilo they wanted me to leave the car there with 'free hand' to change parts.
But I didn't do that because I know they are crooks. To fix the electric steering problem they will always charge thousands when the problem is fixable by only changing the battery. I did that!
Even a friend of mine who is an owner of an auto repair shop, at the time wanted to start to change parts all over.
He did that for the braking problem...

I just found now this post...

https://www.fiatforum.com/stilo/238308-1-9-jtd-temporary-loss-poor-brake-pedal-switch.html

Before I already cut the 2 wires that theoretical send the ECU signals to cut the fuel... no success in fixing my problem.
The brake switch has 4 wires. 2 control the lights and 2 send something to the ECU. This is a theory.
There is a switch for the panda with only 2 wires (it costs 4x more). The plug is not the same as the one in my car.
No ESP and ASR in my car. But 2 months after they started to install those as Standard. My car is from October 2004.

Learned this now (ASR cuts power or fuel at the turbo or cylinder) :
[ame]http://en.wikipedia.org/wiki/Anti_slip_regulation[/ame]

Many people having this problem but never a solution.

I bought two elm327 readers (one usb for the computer, another bluetooth to use with the android phone), to always check for ecu errors. Even while I'm driving.
No errors in my car.