Accelerator pedal (AP) fault codes

[foggyjames]

Hi all,

Happy Christmas fault code advice required!

My old man's 2009 V50 T5 (35k miles) has been gone into limp-home mode three times over a couple of months. I read the codes yesterday, a couple of weeks after after the second event, and got...

ECM-941D - AP sensor, analogue signal - Signal too low
ECM-9430 - AP sensor, analogue signal - Faulty signal
CEM-3F93 - AP sensor - Signal too low

Then last night it shut down again, and repeated ECM-941D and CEM-3F93.

The first two shut-downs were straight after a cold start. Yesterday's was on the move. Gut feeling...it's either the pedal sensor itself (I know these can give trouble), or a wiring issue.

I've heard good reports of people cleaning the tracks inside the pedal. Any views?

Your thoughts, please!

cheers

James

[Clan]

Originally Posted by foggyjames

Hi all,

Happy Christmas fault code advice required!

My old man's 2009 V50 T5 (35k miles) has been gone into limp-home mode three times over a couple of months. I read the codes yesterday, a couple of weeks after after the second event, and got...

ECM-941D - AP sensor, analogue signal - Signal too low
ECM-9430 - AP sensor, analogue signal - Faulty signal
CEM-3F93 - AP sensor - Signal too low

Then last night it shut down again, and repeated ECM-941D and CEM-3F93.

The first two shut-downs were straight after a cold start. Yesterday's was on the move. Gut feeling...it's either the pedal sensor itself (I know these can give trouble), or a wiring issue.

I've heard good reports of people cleaning the tracks inside the pedal. Any views?

Your thoughts, please!

cheers

James

Hi James !

Firstly the 2 ECM codes are being caused by the CEM code so you can ignore those .
It may help if you know how it works :
The pedal sends out 2 signals , One is digital and goes direct to the ECM , the other is analogu a 0 - 5 volt signal varying with throttle position . This goes direct to the CEM and is converted in the CEM and sent on the network system to the ECU . This is like a plane where everything is duplicated .
So the ECU monitors these two signals and they must both give the same reading in the ECU .

This signal is only failing intermittantly so any fault tracing you do is going to show ok you are never going to be lucky enough to catch the sytem in the fail mode to fault trace it .

I would check the wiring plug on the pedal first . unplug it and with a thin terminal of similar size just press it into each socket in the plug one by one to make sure there is drag when you insert and pull it out . This will test that the terminal is in fact gripping the pins in the pedal socket ..
Get some volvo rapid rust loosener 1161658 and spray the socket and put it back .
next remove the CEM and do the same with the relavent plug which contains the pedal signal wire . Check all the CEM pins for corrosion especialy the big green one .

Hopefully this will do the trick although it may be some weeks before you know .
If it still happens you could run a new wire down from the pedal to the CEM .
Changing the pedal is the last thing before changing the CEM or ECM .. I have never found a pedal which is actualy faulty with this problem .
You do get it serviced properly and have the software updates i take it .. The CEM gets updated at every service so you need to know this has the latest software .

I hope that helps ,

[foggyjames]

Hi Nick,

Many thanks for your expert assistance, and for confirming my suspicion that this would not be as simple as a failed pedal. A couple of quick questions, if I may...

Is the rust loosener a contact cleaner? I don't have ready access to the Volvo stuff (see below), but I can probably find a substitute.
Where is the CEM located on these cars?

The car gets serviced as a local independent Volvo specialist, but they don't have access to VIDA, as far as I'm aware. The nearest dealer is a considerable drive away, sadly, although making a special trip for a software update won't be a problem. I remember you saying something similar about my V70's SAS error...which I must confess I have yet to get around to looking at!

In other news, I was hearing last night that the "other" local indy replaced a pair of track rod ends, then didn't check/adjust the tracking, which proved (weeks, and considerable tyre-wear, later) to be 20+ degrees out! That one left me open mouthed...

cheers

James

[Clan]

Originally Posted by foggyjames

Hi Nick,

Many thanks for your expert assistance, and for confirming my suspicion that this would not be as simple as a failed pedal. A couple of quick questions, if I may...

Is the rust loosener a contact cleaner? I don't have ready access to the Volvo stuff (see below), but I can probably find a substitute.
Where is the CEM located on these cars?

The car gets serviced as a local independent Volvo specialist, but they don't have access to VIDA, as far as I'm aware. The nearest dealer is a considerable drive away, sadly, although making a special trip for a software update won't be a problem. I remember you saying something similar about my V70's SAS error...which I must confess I have yet to get around to looking at!

In other news, I was hearing last night that the "other" local indy replaced a pair of track rod ends, then didn't check/adjust the tracking, which proved (weeks, and considerable tyre-wear, later) to be 20+ degrees out! That one left me open mouthed...

cheers

James

The Rapid rust loosener is slighty acidic so it actualy cleans the connectors of any corrosion , rather than just cleans grease off like brake cleaner or lubricates to prevent the air getting to the contact points .
It is brilliant on manifold studs and other stiff or rusy threads . I always keep a can in my box despite it being £6 a can . well worth it .

The CEM is under the glove box , the big white unit with the fuses in ,it has about 3 plugs on the underside , then it will hinge down after removing two thumb screws , then you can remove the other 5 or so plugs and remove the CEM from it's bracket , it kind of slots out .
Disconnect battery first then all you will loose is the time !

[foggyjames]

Thanks Nick - I'll have a play if the rain ever lets up!

cheers

James

[Clan]

Originally Posted by foggyjames

Thanks Nick - I'll have a play if the rain ever lets up!

cheers

James

yes indeed , bridge on the point of closing here and gales and lashing rain i havent been in my garage for a week !

[SonyVaio]

Originally Posted by foggyjames

Thanks Nick - I'll have a play if the rain ever lets up!

cheers

James

That'll be a job for next year then??

[Pete-V70 D5 2003]

Originally Posted by Clan

Hi James !

Firstly the 2 ECM codes are being caused by the CEM code so you can ignore those .
It may help if you know how it works :
The pedal sends out 2 signals , One is digital and goes direct to the ECM , the other is analogu a 0 - 5 volt signal varying with throttle position . This goes direct to the CEM and is converted in the CEM and sent on the network system to the ECU . This is like a plane where everything is duplicated .
So the ECU monitors these two signals and they must both give the same reading in the ECU .

This signal is only failing intermittantly so any fault tracing you do is going to show ok you are never going to be lucky enough to catch the sytem in the fail mode to fault trace it .

I would check the wiring plug on the pedal first . unplug it and with a thin terminal of similar size just press it into each socket in the plug one by one to make sure there is drag when you insert and pull it out . This will test that the terminal is in fact gripping the pins in the pedal socket ..
Get some volvo rapid rust loosener 1161658 and spray the socket and put it back .
next remove the CEM and do the same with the relavent plug which contains the pedal signal wire . Check all the CEM pins for corrosion especialy the big green one .

Hopefully this will do the trick although it may be some weeks before you know .
If it still happens you could run a new wire down from the pedal to the CEM .
Changing the pedal is the last thing before changing the CEM or ECM .. I have never found a pedal which is actualy faulty with this problem .
You do get it serviced properly and have the software updates i take it .. The CEM gets updated at every service so you need to know this has the latest software .

I hope that helps ,

Hi Guys, thanks for your help here some great insights to check. I have a 2010 facelift V50 1.6Eco and have had almost every dodgy wiring issue going from steering lock reset etc. Over the last year have cleaned up all the relays, fuses, cem etc etc and all good. Last issue was throttle pedal one. Various codes pointing to dodgy connections. Took pedal off and cleaned up all contacts and buggered up the plastic bits using modern wd40 (crap) and pedal was no longer smooth but errors went away for a few months. i dont really use the car too much anyway so a few months here doesnt equate to thousands of miles, maybe a 1000 or so. Cant recall codes offhand at the mo but main issue was power reduction and engine service required. You could drive through these for a shortish distance and it would cure itself. But its back again on last trip as I slowed down in traffic, but again a few moments later it cleared itself.

I was going to get a used pedal 4M51-9F836-BK which seems the same as mine despite many differing vehicles using the same one. But I thought I should try your tip on checking voltage pedal to cem. And then it occurred to me lots of these silly problems can often be cured by a software update. Fords were notorious for it. What do you think? If so is there a way to establish what software version I have on the car and what software version is the latest? I guess the latest could be 5yrs old or more but its a good place to start, just ensure you have latest software update? If so how can it be done and what would the costs be ish?

If you think its software first I'll go for that, then the pedal wire to cem, then maybe another pedal and after that if it still happens Im stuffed. Cheers

[Clan]

Originally Posted by Pete-V70 D5 2003

Hi Guys, thanks for your help here some great insights to check. I have a 2010 facelift V50 1.6Eco and have had almost every dodgy wiring issue going from steering lock reset etc. Over the last year have cleaned up all the relays, fuses, cem etc etc and all good. Last issue was throttle pedal one. Various codes pointing to dodgy connections. Took pedal off and cleaned up all contacts and buggered up the plastic bits using modern wd40 (crap) and pedal was no longer smooth but errors went away for a few months. i dont really use the car too much anyway so a few months here doesnt equate to thousands of miles, maybe a 1000 or so. Cant recall codes offhand at the mo but main issue was power reduction and engine service required. You could drive through these for a shortish distance and it would cure itself. But its back again on last trip as I slowed down in traffic, but again a few moments later it cleared itself.

I was going to get a used pedal 4M51-9F836-BK which seems the same as mine despite many differing vehicles using the same one. But I thought I should try your tip on checking voltage pedal to cem. And then it occurred to me lots of these silly problems can often be cured by a software update. Fords were notorious for it. What do you think? If so is there a way to establish what software version I have on the car and what software version is the latest? I guess the latest could be 5yrs old or more but its a good place to start, just ensure you have latest software update? If so how can it be done and what would the costs be ish?

If you think its software first I'll go for that, then the pedal wire to cem, then maybe another pedal and after that if it still happens Im stuffed. Cheers

as i said its never the pedal ,
you need to get a new plug shell for the throttle pedal and renew the terminals too , they have lost their springy grip on the pins , also the other end of the signal wire to the CEM put a new terminal repair wire on that too.

[Pete-V70 D5 2003]

"as i said its never the pedal"

Well that saves a £40 punt then on a used one.

"you need to get a new plug shell for the throttle pedal and renew the terminals too , they have lost their springy grip on the pins"

You mean as in a new part? Whats that called in their lingo?

"also the other end of the signal wire to the CEM put a new terminal repair wire on that too"

OK thats the next project then thanks.

Any thoughts on the software update idea?