Fiat stilo JTD problem

[jonniebravo]

Hi guys,
I have problem with fiat stilo jtd 115hp, 192A1.000.
Problem is not consistent, it comes from time to time, car all by itself starts adding throttle.
It revs up to 3 or 4000 rpm without touching anything. I checked with KTS and I have error that APP(Accelerator Pedal Position) potentiometer 2 is not ok and also error P1555 for brake switch.
When i go to live data in kts I can see that potentiometer 2 signal is not consistent, in neutral position it should be giving 0,3-04 volts and when pedal fully pressed 1,8 volts.
It has that scope of voltages and it is linear but from time to time i can see that signal goes to 0 volts, its random, it happens no matter in what position pedal is. Car was tested with another accelerator pedal and its the same.
I took scope and connected it to signal wire on ECU connector(80) and ground(79), signal looks like on attached picture(its just drawing scope.jpg) it looks like 0,4 volt drops, i noticed that they are all of the same length.

I was unable to diagnose car when it starts acting crazy, because when car arrives at my place it works normally.




Has anyone ever had problem like this?
And if you had this problem, please don't tell me that car was fixed all by itself.

As for error with brake switch I searched through fiat forums, and it's common error which occurs when you press both accelerator and brake pedals in the same time. I also "recalibrated" brake switch, i.e. pulled it down and let brake pedal push it back in it's final position.

[dopsleutel13]

Looks like connector D4 problem (mostly common)

[jonniebravo]

Checked before, all contacts from accelerator pedal are copper ones and they are all clean and shiny.
When you plug in connector hissing sound is heard so its water tight.

D4 is located under fuse box in engine compartment or is it another one?

[dopsleutel13]

D4 is near the engine .
But you can get the whole Elearn from this https://rapidshare.com/files/1724886...Fiat_Stilo.rar to look at yourself ! its all in it in most langua .

[jonniebravo]

i have elearn, it is wrong position in drawing, it is near engine but under fusebox, it has three rows of contacts. pedal contats are in the middle row(marked B).

[dopsleutel13]

Yes marked as B2 - - - - -B7
Cut the wires and soldered and try again (was a solution by the Lancia Lybra by Fiat technical bulletin)

[jonniebravo]

you mean i cut them from connector, and solder them directly??

[dopsleutel13]

Yes, (burned contacs in the connector you ca'nt repair)
The you are for sure its ok !

[jonniebravo]

ok i will do that, will post results back as soon as i finish.

[dopsleutel13]

ok i will do that, will post results back as soon as i finish.

on holiday ?

[Meat-Head]

on holiday ?

some members do but at all costs come on here to assist

[jonniebravo]

No I'm not on holiday....just nothing happens....I don't wanna do anything if this problem doesn't repeat, problem occurred several times during that week, now it's gone.
As soon as it happens I'm getting rid of connector.
Anyway, dopsleutel13, those technical bulletins by fiat, you got them in some sort of software(like alldata) or what?

[dopsleutel13]

No I'm not on holiday....just nothing happens....I don't wanna do anything if this problem doesn't repeat, problem occurred several times during that week, now it's gone.
As soon as it happens I'm getting rid of connector.
Anyway, dopsleutel13, those technical bulletins by fiat, you got them in some sort of software(like alldata) or what?

Straight from Fiat as PDF