Hi all

I have an 05 Panda Semi Auto 1.2. It starts up immediately and idles fine but no response when I press the accelerator......the revs rise maybe to 1200-1300 rpm but that's it......barely above idle.

I have a basic OBD reader and there were a fair few codes so I erased them all and tried again and now I have 2 consistent codes - P1121 and P1122 related to Throttle Position Sensor/Potentiometer tracks 1 and 2?

I have pulled multi plugs on the TB, the ECU and accelerator pedal and given them a spray with a contact cleaner but to no avail. I have looked through the history of the car and it seems this problem has occurred before and it appears the garage replaced the accelerator pedal back in 2009.

Unfortunately, the car is away from my home so I am wondering/hoping if it is a simple case of replacing a part, I can fix it and drive it home or I may have to consider getting it recovered back home or to a garage.

I have read many topics of a similar nature but haven't seen a definite solution. The pins on the ECU multi plugs look good and not bent. I've tried some wiggling of wires but I was on my own so didn't have anyone to try the throttle at the time to see if anything changed. I've pressed the butterfly open and the revs started to rise but coughed as I suspect too much air being allowed in and no increase in fuel?

Any ideas or advice would be helpful.

kcdionysus said:

Hi all

I have an 05 Panda Semi Auto 1.2. It starts up immediately and idles fine but no response when I press the accelerator......the revs rise maybe to 1200-1300 rpm but that's it......barely above idle.

I have a basic OBD reader and there were a fair few codes so I erased them all and tried again and now I have 2 consistent codes - P1121 and P1122 related to Throttle Position Sensor/Potentiometer tracks 1 and 2?

I have pulled multi plugs on the TB, the ECU and accelerator pedal and given them a spray with a contact cleaner but to no avail. I have looked through the history of the car and it seems this problem has occurred before and it appears the garage replaced the accelerator pedal back in 2009.

Unfortunately, the car is away from my home so I am wondering/hoping if it is a simple case of replacing a part, I can fix it and drive it home or I may have to consider getting it recovered back home or to a garage.

I have read many topics of a similar nature but haven't seen a definite solution. The pins on the ECU multi plugs look good and not bent. I've tried some wiggling of wires but I was on my own so didn't have anyone to try the throttle at the time to see if anything changed. I've pressed the butterfly open and the revs started to rise but coughed as I suspect too much air being allowed in and no increase in fuel?

Any ideas or advice would be helpful.

Click to expand...

have you checked the movement on the throttle cable at the engine end of it
make sure is moving fully, some have a clip that holds the outer of the throttle cable as a adjustment to take up the slack, if this falls off you hardly get any throttle action putting a couple of tie wraps on it can make a semi perm cure
also try moving by hand and see if it revs then
hope this helps

is it fly by wire like an air france airyplane?

It's a 'fly by wire' type arrangement so no cable other than an electronic one to send the signal that the accelerator is being pushed.

My basic understanding is that it could be the 'sender' unit on the accelerator pedal, and looking again through the service history, it looks like there was an issue back in 2009 where the pedal was replaced only to be investigated again a couple of months later with a similar issue but the notes in the history suggest the garage couldn't replicate the fault the customer was having. That suggests to me that this car has perhaps had some history related to this type of problem and the pedal is faulty again or, perhaps it's not the pedal but the 'receiver' end interpreting the signal. This is where I'm not certain how it works i.e. where does the signal goes..... is it via the ECU to be processed and the command sent to the throttle body or something else?

kcdionysus said:

It's a 'fly by wire' type arrangement so no cable other than an electronic one to send the signal that the accelerator is being pushed.

My basic understanding is that it could be the 'sender' unit on the accelerator pedal, and looking again through the service history, it looks like there was an issue back in 2009 where the pedal was replaced only to be investigated again a couple of months later with a similar issue but the notes in the history suggest the garage couldn't replicate the fault the customer was having. That suggests to me that this car has perhaps had some history related to this type of problem and the pedal is faulty again or, perhaps it's not the pedal but the 'receiver' end interpreting the signal. This is where I'm not certain how it works i.e. where does the signal goes..... is it via the ECU to be processed and the command sent to the throttle body or something else?

Click to expand...

I haven't got the schematics in front of me at this moment, but can check tomorrow, but, my understanding is that the pedal connects to ECU, ECU to throttle valve actuator.

Due to history, I would be loathe to replace the pedal unit without some in depth investigations. It sounds more like a fault elsewhere, wiring/loom or else ECU.
The only real way forward I believe, is to get it to a fiat dealer, or,get mes registered and look at the output of the pedal unit.
No quick fix I can see,unfortunately.

It's how I thought it would be set up with the connections all going via the ECU and I agree that a more in depth investigation is probably the way forward as just replacing random associated parts isn't the best way to fix a problem. Unfortunately, some garages do work like this but the ones I trust are near me so I might see what it will cost to get the vehicle recovered back to one of them.

But because it seems, to my simple mind, to be either the accelerator pedal or the ECU (or the throttle body but the previous owner replaced that so I have the new one and the old one with the car), it might be more cost effective for me to get the ECU sent away and tested/fixed as well as a replacement pedal rather than get the car recovered, diagnosed and fixed by a garage.

Is it worth getting some software like Fiatecuscan and a cable to help me? Is it fairly easy/intuitive to use or is it really for those with specialist knowledge?

Hi ,
I think the only course of action is further diagnosis.
However, on checking, the last price I have for the pedal for your selespeed with 'drive by wire' model, it is only 73 GBP inc vat. for the complete electronic pedal. which is rather good ! -
In that case, I might be tempted to try it...
It is unusual, but not unheard of, to have 2 failures of the same part.
It is always difficult to virtually impossible with the handheld generic diagnostic units to tell what is happening - or even be pointed in the right direction - in this case, there may be information stored in the efi ecu and also in the selespeed ecu that could confirm diagnosis as the drive by wire is fitted as part of the selespeed system and integrated - although FROM the efi ecu to the selespeed ecu.
I expected the pedal to cost a fortune, a pleasant surprise for a change !.
(still 14 quid cheaper in Portugal !) gawd know why they alter the prices - the car actually costs MORE here to buy >!
Anyway, hope you get it sorted.
Cap.

=kcdionysus;3456259
Is it worth getting some software like Fiatecuscan and a cable to help me? Is it fairly easy/intuitive to use or is it really for those with specialist knowledge?

Click to expand...

Absolutely 100% !!
Get MES (Multiecuscan V19 registered) - or, the Multiplex version)
You would need an ELM327 interface - I posted an article recently on selecting and modifying a suitable unit for the panda with no extra leads.
I think EVERY owner of a fiat with a hint of interest or aptitude should have this product. The first time you need it - it WILL pay for itself.
Mine saved me thousands - literally - as it identified one clocked 4 year old car ... It saved me the expense of a new EPS assembly - the fault was purely battery and terminal related. Allowed me to do a phonic wheel calibration after timing belt change and many other items. I use it to check the car on a routine basis - ALL ecus -
I consider it a MUST HAVE item.
heres the thread.
I have a few interfaces here already modded if you need one contact me.
https://www.fiatforum.com/panda/347352-selecting-modifying-interface-panda-diagnostics-mes-how.html

But it is fairly straight forward if you have a soldering iron - whatever is best.

Here is some more info regarding the latest chinese elm interfaces - ALL of them - from the MES site.
The later boards in my thread are slightly different layout, but they still are wired incorrectly and can cause issues without the removal of the un-needed and unnecessary resistor across the canbus lines !
http://forum.multiecuscan.net/viewtopic.php?f=5&t=1493

edit - re easy and intuitive to use -
My opinion is that any one with a reasonable understanding of the workings of a modern vehicle, a modicum of awareness of canbus, ecus, actuators, sensors etc - as well as the standard mechanical and electrical knowledge of vehicles in general, would have no problem using the software at all. It is very intuitive and easy, but presumes a reasonable level of competence in the user.
It is also a product where one HAS to be fully aware of ones own abilities and lack of in some cases - if there is an adjustment etc, that you do not 100% understand and know you need to do, and why - then dont touch it. It is also not a product for experimenters to probe about with on a 'what does this button do ?' basis lol

I dont think you would have any issues, you have already displayed a good understanding of the issue. That is more than most as they dont have the experience, unfortunately.
It is a superb diagnostic, testing, and setup tool - the only one at anywhere near the price.
Beware of pirated versions of the older FES software, and any MES - if you use them on your vehicle, you are asking for trouble - they are simply dangerous. And, the product is only 50 euros - a total bargain.

Thanks for the info Cap.....it's appreciated. I think I'll get the MES anyway as the Panda isn't the only Fiat we have at present and I'm looking to getting an Alfa as well to which the MES works on them too from what I understand.

As for replacing the parts, as you have seen, a pedal unit is circa £73 and I believe an ECU test, and if needed a repair, is circa £200 so I'm tempted to go for it as a recovery, diag and repair at a garage is likely to cost more BUT I would be sick as a pig if if didn't work and I had to recover it anyway?? It looks like there has been similar issues before and the appointed garage at the time replaced the pedal unit but it looks like a similar, intermittent issue occurred within the same month so to me, it seems like maybe the pedal wasn't the cause of the original problem or maybe it's just bad luck that the new one is/was faulty.

My inclination is still the ECU playing up but I'm wondering if Panda's suffered with anything like maybe water or debris getting into the footwell and to the pedal unit perhaps and corroding the connections? I think I might go back to the car with a decent torch and have a better look at all the connectors to do with the pedal, TB and ECU just to satisfy myself it's not something more simple/obvious.

I agree with your thoughts sir.
The re-occurance of the issue is troublesome -and - as you say, would tend to be indicative of another issue. I doubt ecu as I dont think the replacement pedal would have worked - sounds more like connection / wiring and I think the detailed look with torch etc is definitely worth doing. !. I am not aware of any specific issues with water coming into the car - but, I really dont know - someone else may have a better idea...
If it was a Smart Roadster - yeah lol ! - water on the electronics.. .. yuk..
Is there any indication in the history of what the second repair consisted of after the pedal ?

If I WAS going to get a new pedal - I would be tempted firstly - to remove the old one and 'dismantle it' and examine it... even if it 'pretended' to refuse .... ....

There is a documented case on here recently of an issue with connection problems at the pedal - cured by cleaning - that caused weird and wonderful rpm states..
best of luck and keep us updated.

Haven't checked the Panda, but the Stilo's had a notorious (D4) connector under the fusebox (near the battery) where all the CANinfo had to go through. Cleaning this cured many Stilo's. Worth a try IMO.

gr J

Cheers A3, when I go back to the car, I'll have a look.

I've done some more reading about the codes P1121 and P1122 and it would appear that one is for too low a voltage reading detected on the potentiometer and the other is for a voltage detected as being too high.

So that suggests to me to be either a wiring problem or a duff ECU??

I think I'll definitely go and look over the wiring and harnesses more carefully (I had my young nephew with me the last time who was being a little distracting) and see if it's a dirty connection or something like a dodgy earth somewhere.

kcdionysus said:

I've done some more reading about the codes P1121 and P1122 and it would appear that one is for too low a voltage reading detected on the potentiometer and the other is for a voltage detected as being too high.

So that suggests to me to be either a wiring problem or a duff ECU??

I think I'll definitely go and look over the wiring and harnesses more carefully (I had my young nephew with me the last time who was being a little distracting) and see if it's a dirty connection or something like a dodgy earth somewhere.

Click to expand...

Actually, I would still presume the fault is the actual pedal assembly - the ecu would be my last suspect, by a long way.
The wiring is a possibility, but ... if the pedal has malfunctioned both tracks could be damaged - anyway, here is the connector, and here is the diagram, so with a reasonable multimeter you can test the pedal...
It also gives you the pins on the ecu to do a continuity check of the wiring IF the pedal tests ok - .
I would, at this stage, go for pedal check first - its an easy one to do .
You should have the same resistance across the main pot terminals A and B
and also D and E, then you should have the wiper value varying with pot movement on pin C for Pot A/B and also on F for pot D/E

measure reisistance from A to B and then from D to E first, that is the pot value and should be equal - not sure of the value - probably 1 to 20k ?? - and fixed.
then resistance from A to C AND from B to C is the wiper, and should vary as the pedal is moved - apart from being in the reverse direction, the resistance should vary across the range from BOTH A to C and B to C.

the same test for the second Pot D-E with wiper F

this can be done of the car.

There is a resistor shown in the wiper circuits, but I expect it is small, it is to stop the output being connected directly to source or sink.

On the car - test for power at pins A and D of the throttle loom connector, and ground on B and E

refer to schematic. EDIT - Throttle is location K055 !! - the two potentiometers can clearly be seen.

hope that helps.

Cap.

OK - went down to the car and took the accelerator pedal off. Terminals are all pretty clean with no corrosion.

I have set my multi-meter to 200k and got the following results with the pedal off the car and moving the potentiometer the same way each time and the way the throttle would be if pressing the accelerator:

A-B reading 1.7 no movement
A-C reading 2.6 - 2.0 when moving the potentiometer
B-C reading 1.1 - 1.8 when moving the potentiometer

D-E reading 1.1 no movement
D-F reading 1.9 - 1.1 when moving the potentiometer
E-F reading 1.2 - 2.0 when moving the potentiometer

I'm not an auto electrician and my knowledge is limited so if Cap, or anyone else, understands this, could they give me an idea if the accelerator pedal is OK and within tolerances or not? The AB and DE resistance readings are different and the ranges are different but there is variance when the potentiometer is turned so I don't know if this means it's not working correctly??

kcdionysus said:

OK - went down to the car and took the accelerator pedal off. Terminals are all pretty clean with no corrosion.

I have set my multi-meter to 200k and got the following results with the pedal off the car and moving the potentiometer the same way each time and the way the throttle would be if pressing the accelerator:

A-B reading 1.7 no movement
A-C reading 2.6 - 2.0 when moving the potentiometer
B-C reading 1.1 - 1.8 when moving the potentiometer

D-E reading 1.1 no movement
D-F reading 1.9 - 1.1 when moving the potentiometer
E-F reading 1.2 - 2.0 when moving the potentiometer

I'm not an auto electrician and my knowledge is limited so if Cap, or anyone else, understands this, could they give me an idea if the accelerator pedal is OK and within tolerances or not? The AB and DE resistance readings are different and the ranges are different but there is variance when the potentiometer is turned so I don't know if this means it's not working correctly??

Click to expand...

Hi mate,
I have never had the pleasure of actually measuring a fiat one - I was hoping you had an O/C or S/C issue and we could say a definite issue - but at least there is function - , but, the best way to look at this properly is on a dual channel scope with voltage applied.


I would, though, have also expected the pot value to be the same (the actual value measured from A-B and D-E) - the output ranges would normally be different as most systems use a phase shift lag reading (One voltage lags behind the other by a constant rate) - this forms a failsafe check.
Without a scope check, and based on those readings, I would have to say there is a high probability the pedal unit is not working correctly.
You could (with the pdeal off the car) try to apply voltage to AB and DE from a 9v pp3 battery, - then make a rough calibration with masking tape and pen - as the pedal moves, measure the voltages at C and F and plot them against your cal markers (say, 10 marks ?)
Sorry cant help much more. I would probably risk a new pedal at this stage due to the cost of having the vehicle disabled.

I found another thread or two with people who had the same problem but on other cars like Stilo's and they also thought it was the accelerator pedal and/or throttle body but both found the problem to be the ECU.

Another said he 'squeezed' the connectors on the TB and this highlighted the problem of bad connectors. A different thread had a user who checked the resistance on his accelerator pedal and his were similar to mine. In the end, he bit the bullet, put it into a Fiat Dealer and again, ECU was diagnosed as the culprit.

A user called Deckchair5 suggested that P1121 and P1122 are representative of an issue with the signal from the ECU to the throttle body so on the basis my pedal has moving resistance, I would expect something from the engine when I press it. So I'm going to put the pedal back on, have one more look at the connectors and failing that, see if I can send the ECU off for testing/repair.

A diagnostic setup like MES would be useful.
I would also be tempted to take the car to fiat before condemning the ecu.
It is strange that a pedal before fixed the issue for a long time, if anything one would suspect wiring before ecu... fiat can test all with their kit. - well, a good dealer can
best of luck

Deckchair has a lot of knowledge. Fiat do not repair ECU's. They simply replace (and probably repair them and replace again). I'd probably have the ECU checke and repaired as well.

gr J

A3jeroen said:

Deckchair has a lot of knowledge. Fiat do not repair ECU's. They simply replace (and probably repair them and replace again). I'd probably have the ECU checke and repaired as well.

gr J

Click to expand...

I have no issues with having the ecu repaired - and agree fiat are not the ones to do that (repair an ecu) - what I am suggesting is that fiat would be the best people to identify the problem, (or a specialist with the appropriate software) - A MUST !).
One can SEE the pedal tracks independently with the diagnostic software. One can test the throttle body actuator with it,. It is also easy to test continuity in the wiring loom - fiat can do that. That is a simple matter of metering or pin probing into the wiring whilst running.
What I do not recommend, at all !, is sending the ecu away to a repair place without a FULL check on the system first by whoever has the correct equipment. To do this would be more than likely a total waste due to the history of the car. The issue sounds more related to wiring / pedal.. again, both easy to test with the right equipment.
Even if the fault is related to - for example - the tb actuator - sending the ecu off will not fix that. This cold well end up a VERY expensive repair if a swap component trial and error regime is established.
It needs full and appropriate diagnostics at this stage before moving on.