if you think its the pedal take it off and measure its resistance through a full sweep
Technical Tech Help Needed - Throttle Sensor Fault ?
- Thread starter percymon
- Start date
Currently reading:
Technical Tech Help Needed - Throttle Sensor Fault ?
Great advice, not so easily done.
Wrestled with the pedal last night - eventually getting it out by...
1.drilling the rivets holding the electical board
2.disconnecting most of the wiring harnesses going onto the board - about 8 of them from recollection !
3. moving the board out of the way (ha ha given theres nowhere to move it to in a Panda footwell)
4. struggling to release the grey securing clip on the throttle pedal connection,
5. disconnecting the pedal, and then threading it out via the position where the electrical board was.
So on with the test tonight - hopefully its a black/white answer from this test, unlike the throttle body end that was a bit ambiguous
do it in place then, testing it at the ECU.
Results from testing the pedal, all readings from the connector on the pedal assembly...
6 pin connector, singkle row of six labelled A - F
Checked resistance on pins F and E ....
Initially 1.29 kOhm, rising steadily and smoothly to 2.17kOhm as pedal depressed to end stop, releasing pedal saw reading smoothly return to 1.29kOhm
Checked pins F and D...
Initially 2.17kOhm, dropping smoothly to 1.24kOhn when fully depressed, and returning smoothly to 1.24kOhm when pedal released.
Only other readings i could get across combination of pins was 2.05kOhm across pins A and B, which didn't change with pedal operation.
On the basis of the results for F/E and F/D i'm assuming the pedal itself is OK, so its been reinstalled and all connections remade at the electrical board and pedal assembly. Restarted car and no different.
If anyone could point me towards where to measure the same resitance / change at the ecu end (or access to a wiring diagram ?) i could check that tonight.
thanks for the ongoing suggestions T14086
Towing it down to the Fiat delaer late tonight, once the traffic dies down.
Might have another look at the live data if i can beforehand, but needs some input from Fiat now to better diagnose where the issue is. Only problem is they can't look at the car until 7th June, but will try to sneak it into the workshop sooner if they get a cancellation.
Might have another look at the live data if i can beforehand, but needs some input from Fiat now to better diagnose where the issue is. Only problem is they can't look at the car until 7th June, but will try to sneak it into the workshop sooner if they get a cancellation.
Now with Wessex Fiat in Newport - they'll try to fit it in when they can to diagnose the probable root cause.
Well dealer found no more fault codes than I did, not spoken to them since Wednesday but they had been swapping parts with another car to aid diagnosis.
And the result is.....
.. ecu failure.
New one ordered, should be fitted Monday. Asked whether recon units were available and told no, then i find them listed on eper !!
Wallet £765 lighter ! Not very pleasant on a car worth £3k, but its worth £100 if not running !!
I suppose given they did the diagnostics (including swapping bits form another car) they have spent a fair few hours fault finding, some of which is no doubt assigned against the ABS recall job done at the same time. Even if i bought a ecu cheaper elsewhere i'd still be paying them for the fault finding time and have to find somewhere to code the new ecu.
Could happen to any car i guess, but does seem to be lots of mention of engine control issues here lately, and i've never had an issue on any of the other cars i've owned.
.. ecu failure.
New one ordered, should be fitted Monday. Asked whether recon units were available and told no, then i find them listed on eper !!
Wallet £765 lighter ! Not very pleasant on a car worth £3k, but its worth £100 if not running !!
I suppose given they did the diagnostics (including swapping bits form another car) they have spent a fair few hours fault finding, some of which is no doubt assigned against the ABS recall job done at the same time. Even if i bought a ecu cheaper elsewhere i'd still be paying them for the fault finding time and have to find somewhere to code the new ecu.
Could happen to any car i guess, but does seem to be lots of mention of engine control issues here lately, and i've never had an issue on any of the other cars i've owned.
Collected Monday - both ignition keys reprogrammed to new ecu. Wallet £720 lighter but the car is back to good health, and the ABS recall has finally been completed too.
I'm pleased that the car is sorted but... ouch!
wouldn't have mattered much which bit had failed..
throttle pedal ca £700 (even eurocarparts are similar price)
ecu £550
throttle body £550 (£240 from shop4parts though!)
without the dealer swapping bits from other cars it was difficult to pinpoint it to the ecu. I could well have fitted a throttle body, secondhand pedal myself and been no further on fixing the fault and then looking for a used ecu and someone to recode it. either way the bill would have ended up somewhere near the same.
This is one advantage of a main dealer - they can 'borrow' parts to diagnose the fault by process of elimination.
For an independant, it's a big gamble to buy an ECU on a no-return basis.
At least your car is back to full health
For an independant, it's a big gamble to buy an ECU on a no-return basis.
At least your car is back to full health
Resurrecting this thread again !
15 months on and the car at times seems under powered, no matter what you do it just seems 20hp down on power, and its not got a lot to start with !
Then the dreaded EML came on again !!
Diagnostic read P1220, only one number different to the original ecu fault code. Clearing the code did nothing, just reappeared on the next engine start.
Anyway tonight i thought i'd have a play around with ecu connectors, earth points etc. I removed the ecu earth strap from the ecu plate to the car body inner wing, cleaned all the contact points with emery and put it back together. Removed ecu connectors and remade. Did same with the three connectors around the throttle body area (under air intake).
To my surprise the EML went out on the next engine start - whether its good fortune i dunno but its one less thing to worry about overnight.
Other than that the car passed its MOT again recently, but only after yet another wishbone replacement (rear bush gone AGAIN), and a leaking damper on front offside. The other lower wishbone bush is starting to look on its way out (only 2 years old), and the drop links bushes are also starting to crack (again less than 2yrs since replaced).
Good news is the exhaust and battery are still original (now 7yrs old, 55k miles) although the exhaust box is down to its inner skin, the outer having corroded away and fallen off, taken off by me !
Starting to get to the time to chuck this in for something newer, and sadly whilst the bodywork and interior are unmarked, the thought of another Fiat with potential electrical issues puts me off buying another, even with 61 platers available for £6-7k new.
Next car will probably be of German technology, either in the form of a 1-2yr old Skoda Fabia/Roomster or a 2-3yr old Merc A Class.
15 months on and the car at times seems under powered, no matter what you do it just seems 20hp down on power, and its not got a lot to start with !
Then the dreaded EML came on again !!
Diagnostic read P1220, only one number different to the original ecu fault code. Clearing the code did nothing, just reappeared on the next engine start.
Anyway tonight i thought i'd have a play around with ecu connectors, earth points etc. I removed the ecu earth strap from the ecu plate to the car body inner wing, cleaned all the contact points with emery and put it back together. Removed ecu connectors and remade. Did same with the three connectors around the throttle body area (under air intake).
To my surprise the EML went out on the next engine start - whether its good fortune i dunno but its one less thing to worry about overnight.
Other than that the car passed its MOT again recently, but only after yet another wishbone replacement (rear bush gone AGAIN), and a leaking damper on front offside. The other lower wishbone bush is starting to look on its way out (only 2 years old), and the drop links bushes are also starting to crack (again less than 2yrs since replaced).
Good news is the exhaust and battery are still original (now 7yrs old, 55k miles) although the exhaust box is down to its inner skin, the outer having corroded away and fallen off, taken off by me !
Starting to get to the time to chuck this in for something newer, and sadly whilst the bodywork and interior are unmarked, the thought of another Fiat with potential electrical issues puts me off buying another, even with 61 platers available for £6-7k new.
Next car will probably be of German technology, either in the form of a 1-2yr old Skoda Fabia/Roomster or a 2-3yr old Merc A Class.
lamlash
New member
You've been unlucky -it can happen with any car. Many of the sensors and actuators on modern cars are from the same original manufacturer (e.g. Bosch, Siemens etc.) and are just as prone to failure on an £20K A-class Merc as a £6K Fiat Panda.
Before you jump ship, check out the price of a MAF sensor for an A-class and read up on head gasket failure with some of the Fabia / VW Polo engines. Having said that my father in law has systematically and relentlessly abused his 1.4 Fabia over the past 5 years and hasn't had any trouble with it whatsoever, and I quite fancy an A-class Merc myself!
Before you jump ship, check out the price of a MAF sensor for an A-class and read up on head gasket failure with some of the Fabia / VW Polo engines. Having said that my father in law has systematically and relentlessly abused his 1.4 Fabia over the past 5 years and hasn't had any trouble with it whatsoever, and I quite fancy an A-class Merc myself!
Mytheroo
New member
just in case someone else comes across this thread researching a similar problem:
(the following is my understanding, and may not be correct, and is knowledge gained from a 2004 Stilo 1.6)
In order to distinguish between a pedal issue and a throttle valve issue:
When the ignition is turned on but the starter motor not engaged, the ECU will apply a sweeping voltage to the throttle valve DC motor, probably 0v to 12v, in order to test the maximums (as sensed on the two resistance tracks inside the throttle body). This should be audible, and if the air cleaner is removed it should be visible also. As you can see, the accelerator pedal is not involved in any way here, so a lack of movement of the throttle valve during this time points towards:
ECU failure:
option 1: the circuit that applies voltage to the pins connected to the throttle valve motor has fried -- fix is replace the ECU
option 2: the ECU has overheated or experienced mechanical stresss breaking the soldering on the pins that connect to the throttle valve --- fix is to resolder all the pin connectors... needs a quality iron as chunky through-hole connections are being reflowed, and I'd recommend some soldering skills also
ECU Connector or Throttle valve connector (I don't think the D4 connector is used here):
Fix: remove the connectors and spray switch cleaner onto all the contacts, then replace/remove/replace a few times. You could also back-probe continuity between the throttle valve connector and the ECU connector
Throttle valve motor failure:
Remove the throttle body connector and apply a DC voltage to pins 2 and 3 (the motor + and -) 5v will give about half-range travel (which is what I did, using a PC power supply), I'm assuming 12v will give full range travel. There is a return spring which provides counter-torque so in normal use the motor is always straining against the spring, and the voltage applied is determining the angle at which these two forces are equal and opposite.
If the throttle valve doesn't rotate, it is either stuck, or the motor windings are kaput. If the plate rotates by hand then it is more likely that the windings are kaput.
(the following is my understanding, and may not be correct, and is knowledge gained from a 2004 Stilo 1.6)
In order to distinguish between a pedal issue and a throttle valve issue:
When the ignition is turned on but the starter motor not engaged, the ECU will apply a sweeping voltage to the throttle valve DC motor, probably 0v to 12v, in order to test the maximums (as sensed on the two resistance tracks inside the throttle body). This should be audible, and if the air cleaner is removed it should be visible also. As you can see, the accelerator pedal is not involved in any way here, so a lack of movement of the throttle valve during this time points towards:
ECU failure:
option 1: the circuit that applies voltage to the pins connected to the throttle valve motor has fried -- fix is replace the ECU
option 2: the ECU has overheated or experienced mechanical stresss breaking the soldering on the pins that connect to the throttle valve --- fix is to resolder all the pin connectors... needs a quality iron as chunky through-hole connections are being reflowed, and I'd recommend some soldering skills also
ECU Connector or Throttle valve connector (I don't think the D4 connector is used here):
Fix: remove the connectors and spray switch cleaner onto all the contacts, then replace/remove/replace a few times. You could also back-probe continuity between the throttle valve connector and the ECU connector
Throttle valve motor failure:
Remove the throttle body connector and apply a DC voltage to pins 2 and 3 (the motor + and -) 5v will give about half-range travel (which is what I did, using a PC power supply), I'm assuming 12v will give full range travel. There is a return spring which provides counter-torque so in normal use the motor is always straining against the spring, and the voltage applied is determining the angle at which these two forces are equal and opposite.
If the throttle valve doesn't rotate, it is either stuck, or the motor windings are kaput. If the plate rotates by hand then it is more likely that the windings are kaput.
Last edited:
- Joined
- Sep 14, 2009
- Messages
- 19,492
- Points
- 3,294
Motors, generators and coils generally don't smell of anything. The familiar smell of burnt insulation is a handy hint that problems are brewing if not already landed.
