P1220 ACCELERATOR PEDAL POSITION SENSOR 1/2 CORRELATION
Technical Sluggish Panda 1.2 Euro 5
- Thread starter Martijn169
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Technical Sluggish Panda 1.2 Euro 5
Martijn169
New member
I really appreciate your involvement. I can not thank you enough for that.
I understand it is a process of analysis and deduction. Until we find a likely cause I will not swap parts anymore.
Access isn't good
There's a connector on the top of the pedal that often goes green and furry, especially if the duck bills have been clogged (scuttle drains)
Needs looking at
Some people have had success by blowing with compressed
There's a connector on the top of the pedal that often goes green and furry, especially if the duck bills have been clogged (scuttle drains)
Needs looking at
Some people have had success by blowing with compressed
Martijn169
New member
Is this the specific Fiat explanation of this fault?
That would point towards the accelerator pedal?
I have read that the reading of sensor E should be approx. half of the reading of sensor D?
Is this right for Fiat as well?
My readings were aprrox. equal.
It's a fairly common fault
It reduces power and acceleration so I would say this and no check light would be your only problems along with the MAP misting up
Let's concentrate on the P1220 for now
Here an explanation
THEORY OF OPERATION
The Electronic Throttle Control (ETC) system uses two accelerator pedal position (APP) sensors to monitor the
accelerator pedal position. The APP sensors 1 and 2 are located within the pedal assembly. Each sensor has a 5
Volt reference circuit, a low reference circuit and a signal circuit. Processors are also used to monitor the ETC
system data. The processors are located within the Powertrain Control Module (PCM). Each signal circuit
provides processors with a signal voltage proportional to pedal movement. The processors share and monitor
data to verify that the indicated APP calculation is correct.
WHEN MONITORED
With the ignition on and no APPS No. 1 and APPS No. 2 DTC present.
SET CONDITION
APPS values No. 1 and No. 2 are not coherent. Idle is additionally forced when the brake pedal is pressed or
failed. Acceleration rate and Engine output are limited. One trip fault and the code will set within five seconds.
ETC light is flashing.
It reduces power and acceleration so I would say this and no check light would be your only problems along with the MAP misting up
Let's concentrate on the P1220 for now
Here an explanation
THEORY OF OPERATION
The Electronic Throttle Control (ETC) system uses two accelerator pedal position (APP) sensors to monitor the
accelerator pedal position. The APP sensors 1 and 2 are located within the pedal assembly. Each sensor has a 5
Volt reference circuit, a low reference circuit and a signal circuit. Processors are also used to monitor the ETC
system data. The processors are located within the Powertrain Control Module (PCM). Each signal circuit
provides processors with a signal voltage proportional to pedal movement. The processors share and monitor
data to verify that the indicated APP calculation is correct.
WHEN MONITORED
With the ignition on and no APPS No. 1 and APPS No. 2 DTC present.
SET CONDITION
APPS values No. 1 and No. 2 are not coherent. Idle is additionally forced when the brake pedal is pressed or
failed. Acceleration rate and Engine output are limited. One trip fault and the code will set within five seconds.
ETC light is flashing.
I did notice when you started the engine it was at 1.5K rpm before dropping to the correct 1.2K rpm
I normally start by looking at the live data from track A and B, if you slowly push the pedal up and down it should graph as a nice curve
I not sure if the software I recommend has the option to plot both potentiometers
Normally when they are faulty the line is jumpy at the begining
I normally start by looking at the live data from track A and B, if you slowly push the pedal up and down it should graph as a nice curve
I not sure if the software I recommend has the option to plot both potentiometers
Normally when they are faulty the line is jumpy at the begining
Yes the codes are model specific
The extract above is from the
CHRYSLER GROUP official Worksop manual for the fiat 500, which is usually near enough as the system is almost identical
P0??? Codes are set in stone
P1??? Are different manufacturers to manufacture and sometimes between models
The extract above is from the
CHRYSLER GROUP official Worksop manual for the fiat 500, which is usually near enough as the system is almost identical
P0??? Codes are set in stone
P1??? Are different manufacturers to manufacture and sometimes between models
Heres an example if a corroded pedal connector
Incorrect
Both tracks are supplied with 5 volts
I can't remember the exact figure they are slightly offset from each other
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I've had a pedal sensor fault - it immediately brings up ECU fault light and would not rev past @2000rpm.
Martijn169
New member
Tomorrow I will remove the accelerator pedal assembly and inspect the electrical connector.
I will also try to make a recording of the APPS wheb applying the pedal.
One thing worth mentioning is that when I delete DTC 1220, it will appear again without me touching the accelerator pedal. So if there is an inconsistency in the sensor readings it is also there at the beginning of the stroke.
I will also try to make a recording of the APPS wheb applying the pedal.
One thing worth mentioning is that when I delete DTC 1220, it will appear again without me touching the accelerator pedal. So if there is an inconsistency in the sensor readings it is also there at the beginning of the stroke.
We know there's a problem with the voltage seen by the ECU
We don't know whether it's
A 5 volt supply problem
A reference ground problem
A signal wire problem
A faulty potentiometer in the pedal
A high resistance corroded connector
A faulty ECU
And probably something I have missed
If we had a spare pedal we could just change it and either change if the fault is fixed or move on to further checks if it's the same
If there is a problem with the pedal it's nearly always at the begining of it travel, the part that gets used the most, it normally visible on software that can graph both potentiometers, they should run parallel to each other if there's spikes on one track near the begining or it's not settling in the same place, but fine later in it's travel we know the pedal faulty
We don't know whether it's
A 5 volt supply problem
A reference ground problem
A signal wire problem
A faulty potentiometer in the pedal
A high resistance corroded connector
A faulty ECU
And probably something I have missed
If we had a spare pedal we could just change it and either change if the fault is fixed or move on to further checks if it's the same
If there is a problem with the pedal it's nearly always at the begining of it travel, the part that gets used the most, it normally visible on software that can graph both potentiometers, they should run parallel to each other if there's spikes on one track near the begining or it's not settling in the same place, but fine later in it's travel we know the pedal faulty
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Martijn169
New member
Just yet I used the OBDII dongle to look for irregularities in the accelerator pedal.
When I don't touch the pedal the APPS readings are 15% and 21%. This seems quite a difference to me. And it would fit the observation that the P1220 DTC returns immediately, also when the pedal is not touched.
I have also removed the pedal to look for signs of corrosion in the connector. None were found.
@koalar: would you say that this is enough readon to replace the accelerator pedal for another one? They are not that expensive.
I have checked the supply voltage to the pedal: on two pins it is 5 volts. That seems to be ok.
When I don't touch the pedal the APPS readings are 15% and 21%. This seems quite a difference to me. And it would fit the observation that the P1220 DTC returns immediately, also when the pedal is not touched.
I have also removed the pedal to look for signs of corrosion in the connector. None were found.
@koalar: would you say that this is enough readon to replace the accelerator pedal for another one? They are not that expensive.
I have checked the supply voltage to the pedal: on two pins it is 5 volts. That seems to be ok.
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5 volt is correct
Pins look in excellent condition
The two readings are supposed to be offset
I don't know what the rest percentage should be unfortunately, I don't think I have ever posted my cars results, it also depends which software you use as to how the voltages are transferred into percentages
Fortunately @MrMagoo posted a working pedal here https://www.fiatforum.com/threads/ecu-virgin.480009/post-4529609
Pins look in excellent condition
The two readings are supposed to be offset
I don't know what the rest percentage should be unfortunately, I don't think I have ever posted my cars results, it also depends which software you use as to how the voltages are transferred into percentages
Fortunately @MrMagoo posted a working pedal here https://www.fiatforum.com/threads/ecu-virgin.480009/post-4529609
Martijn169
New member
That would be something for me to have a look at.
When I shake the pedal (don't kknow why I did) it ralttles, so there seem to be loose bits in the pedal.
I will let you know about the resistance measurements.
Martijn169
New member
I have done the measurements and don't what to conclude from this.
As the issue arises when the pedal is not pressed it makes sense to look at the second column (first column with measurements).
And as I assume it is not the absolute value that counts but the difference between sensor 1 and 2 it makes sense to compare rows 1-3 to rows 4-6?
Still don't know what to make of it.
| A-B | 1964 | 1960 |
| A-C | 2940 | 2220 |
| B-C | 1423 | 2100 |
| D-E | 1195 | 1190 |
| D-F | 2230 | 1300 |
| E-F | 1408 | 2250 |
As the issue arises when the pedal is not pressed it makes sense to look at the second column (first column with measurements).
And as I assume it is not the absolute value that counts but the difference between sensor 1 and 2 it makes sense to compare rows 1-3 to rows 4-6?
Still don't know what to make of it.
Martijn169
New member
Can somebody provide me with 'absolute pedal postion D and E' information in % from a well working system? Preferably measured when the pedal is not actuated.
This gives me an idea to what extend the data I measured indicates a fault in pedal or not.
Thanks!
This gives me an idea to what extend the data I measured indicates a fault in pedal or not.
Thanks!
Known good left yous right
AB 1753 / 1753. 1964 /1960
AC 2614 / 1961. 2940 / 2220.
BC 1130 / 1792. 1423 / 2100
DE 1090 / 1090. 1195 / 1190
DF 1885 / 1089. 2230 /1300.
EF 1129 / 1946. 1408 / 2250
Not sure what's this is telling us
But the faulty pedal is almost identical to the known good except the faulty track AC
Yet yours are all way high except DE
AB 1753 / 1753. 1964 /1960
AC 2614 / 1961. 2940 / 2220.
BC 1130 / 1792. 1423 / 2100
DE 1090 / 1090. 1195 / 1190
DF 1885 / 1089. 2230 /1300.
EF 1129 / 1946. 1408 / 2250
Not sure what's this is telling us
But the faulty pedal is almost identical to the known good except the faulty track AC
ECU virgin | FIAT Panda (Mk3)
Hi All, I'm chasing a P1221 fault on my Panda Dualogic. I purchased the car in December 2019 and it was working great until a week ago when the MIL flashed up. Anyway, I've confirmed that it is the electronic pedal and it did have severe corrosion on the terminals but I swapped the terminals...
www.fiatforum.com
Yet yours are all way high except DE
Martijn169
New member
Therefore I like to look at the interpretation of the ECU of these numbers.
This interpretation results in an absolute pedal position of 15% and 21%. I can't do the math to get to that conclusion, but the difference seems a bit big to me and would explain the P1220 DTC (faulty correlation between APPS 1 and 2).
I think it is safe to say that the lack of power is caused by some sort of safe mode or limp mode which is activated by DTC P1220.
There are a number of possible causes for this DTC to be set of which the accelerator pedal seems to be the most likely one, given the difference in absolute pedal position and the rattling sound when I shake it.
Besides that, the accelerator pedal is the potential cause that can be ruled out most easy at reasonable cost. And I guess there is no prove againt the accelerator pedal as the cause of this all.
We are lacking both the information and knowledge to find certainty the theoretical way. Then we may have come to the point where simply swapping out this part is the most effective.
Wouldn't you agree?
I posted some diagnostic tests for the accelerator pedal circuit a year or more ago I will see if I can find them
Yes the difference in values seem to point to the pedal, we have a sample size of three, two are the same except for the faulty track and yours is different
It does seem strange that they are both high by the same amount
The three throttle readings we interested in
Throttle pedal position
Throttle pedal track 1
Throttle pedal track 2
Not to be confused with
Throttle (on throttle body)
Throttle track 1
Throttle track 2
From memory, so might be wrong
Throttle pedal position 0% @ idle
Track 1 8% @ idle
Track 2 8.6% @ idle
Throttle 12% @ idle
But it does depend which software you use
Here the values for the signal wires for both potentiometers
Sweep 1 voltage should start at approximately 0.45 of a Volt and go above 4.6 Volts smoothly
Sweep 2 voltage should start at approximately 0.22 of a Volt and go above 2.31 Volts smoothly
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