[aerosam]

Hi everyone,

been having some real trouble with my 156 recently, and it's starting to seriously p*** me off.

It's a 2.0JTS, and a few weeks ago started hesitating under acceleration. This would be closely followed by a MCSF message, which my code reader tells me is "Throttle pedal position sensor A circuit". After speaking to a couple of people I found that this means the throttle pot is faulty, and this is a common problem on 156's. After the message appears, the engine goes into a sort of low power mode, and although the car still drives, it's painfully slow. i can erase the code with my reader, and the car returns to normal, and may be ok for 100 yards or 20 miles but it always comes back.

I replaced the pedal/sensor assembly with a salvage part bought from a well known Alfa breaker, and it cured the problem for a day or 2, but then it came back. I just replaced the pedal again with a brand new one from AR, and guess what, 2 days later and here we go again!!!

I'm not spending any more money on it till i know what's really wrong with it. Effing thing.

Thanks in advance,

Sam.

 

[Karn]

I used to have the same problem, I'm 90% sure your having the same issues. There is a cable connected to the pedal that runs behind the centre console and onto behind the glove box. It is sheathed in a yellow sleeve (much the same as the airbag wiring) Mine had a lable attached to it that read pedometer or something. Anyway, it has a white connection block and this is the issue. It is a common fault on 156's and alot of people have this removed and the wires soldered together (hard wired) I just unplugged mine and plugged it back in and this solved the problem. It has happened again once or twice over the 3 or 4 years I've had my car and doing this has fixed it every time.

You may have to remove the glove box to gain access to this cable as I did.

Hope this helps.

 

[TheMystic]

My 147 has the same error, but mine is the ECU, not the pedal. The pedals don't often fail, but the wiring issue is common. The 147 has much the same connector as karn describes and it's a often the fault.

 

[aerosam]

Right, will have a look at it on my dinner break - thanks!

 

[aerosam]

Ok, had a look. I removed the glove box and found the yellow sheathed wire, but the connector it went into was yellow and purple, not white. The cable contained 2 wires, yellow and yellow/black on one side of the connector to white and green on the other. I disconeccted and reconnected it, will see how it goes this evening on the way home.

I was also reading in this section about the ECU/throttle reset procedure. Does anyone think this would help?

 

[Daffo]

Well did you make it home ok Sam, or is it still naffed?

 

[steveisfrowning]

yeah - how'd you get on Sam?

 

[aerosam]

Nahh, didn't work.

I did get home, but only after having to stop twice to reset the fault codes and get it out of limp mode. But then it got back here (it's about 10 miles each way) this morning no problem at all.

Methinks I'm gonna have to book it in with my local Alfa specialist to trace the fault, probably buried deep in the loom. But if anybody else has any ideas I'll give them a shot first!

 

[Doug164]

It might be worth checking the connectors onto the actual throttle body. I had to disconnect all these last week during the replacement of the alternator.
After refitting everything the car would only idle and wouldn't respond to the accelerator at all and then the idle became very juddery and hesitant. How I cursed !!!
I started checking all the connections at the back of the engine and cleaned them with contact cleaner. It was when I did the small connector on the bottom of the throttle body that it cured the problem much to my relief.
Give it a go and see how you get on.
Doug

 

[aerosam]

Nice one Doug - will have a quick look at that before i set off home, if it isn't still chucking it down with rain outside

 

[aerosam]

Ok it's just getting worse and worse, someone please solve this before I lose my temper completely and weight it in.

It's now hesitating EVERY time I try and give it some welly, MCSF come up and beeps away for a minute or so then shuts up, and it goes into limp mode about 50% of the time.

checked all conections that have been suggested, OBD just keeps reporting the same "throttle pedal switch a circuit" fault code.

 

[v6junky]

I would replace the block connector behind the glovebox. Solder it or use spade connectors. Disconnecting and reconnecting will not solve anything of there is a loose connection inside the block itself. Then have a go at the connector at the throttle body end. Give it a good clean with elctrical contact cleaner and make sure that all pins, especially the female ones look tight.

 

[Karn]

I second the above post. Hard wire the connections behind the glove box or use a different method of connecting them. Even an electrical block connector would give you an idea if that was the problem. If it still doesn't work you at least can tick that off your list of possible causes.

 

[aerosam]

can someone confirm that I'm looking at the right connector block? 2 wires either side yellow and yellow and black to a green and a white of the other side, yellow coloured connector block.

Or is it another?

 

[Karn]

just looked at mine, im V6 so dunno if our will be the same or not. Ok, mine is grey, pink, green, yellow, white, brown connecting into white, yellow, brown, pink, grey, grey. Both sides are shethed in a yellow sleve and has a yellow tag that says cablelettr on it. Hope this helps

 

[aerosam]

Ok had another look during lunch. The only yellow sheathed wire is the one i previously described, and upon further inspection, is clearly going to the passenger airbag.

Found another connector with 5 wires either side, that suspicously wasn't clipped to the panel where it was supposed to be, and had insulation tape binding the loom tape down on one side. I pulled it apart and re-made the connection, all pins look ok. Also re-checked the throttle body connection (was raining last time) and basically opened and closed every connector i could get my hands on behind the glovebox.

Took it for a short test drive, and hey presto, it's working fine again!

I can't believe such a simple thing could cause such problems. I'm no good at soldering, but I have some really cool do-it-yourself connector blocks at home which i used to fabricate the entire loom on my kit car, and will replace the 5-way block if the problem occurs again, which i fully expect it will, soon.

Thanks guys! Will keep you updated!

 

[Karn]

Glad you got it sorted mate. I remember feeling exactly the same way when I finally fixed mine, how could such a minor fix cause such major issues!!!! I know it's been a pain in the behind but at least it's a free fix. That's the sort of problem that could cost someone alot of money if they didn't know about this forum and just took it into the local garage.

 

[v6junky]

Result! :thumbs:

 

[Flo]

Hi All,
I'm having almost the same issue. I'm not really techie (just in IT) but i've got error code P0220 and P1221, after checking many site it looks that this is the fix i've been looking for. Today after work, i'll have my hands full of it, hopefully it work and sort me out. I love my Alfa. this has happened to me on motorway many time (which is dangerous), loss of power, stuck in 2nd Gear, car coughing and throttle lost in transition.

I will let you know if all of above helped me out.

Thanks

 

[Akos_]

Hi Flo,

Did this actually work for you?
I have soldered the white 5-wire connector behind the glove box and still getting the same fault codes.
Do I need to replace the potentiometer assy?

Thanks,
Akos