C5 electrics = 4cyl petrol
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Thread: C5 electrics = 4cyl petrol

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    Default C5 electrics = 4cyl petrol

    So on the 4cyl petrol, the terminal for a "reader' in the glove box has no power coming to, I believe pin no 16. This apparently drives the reader. Does anyone know where the power comes from. I have checked every fuse I can find and all OK. The car runs perfectly for around 10 to 15 kms and then loses power. I have replaced the primary O2 censor and the "map" reader. Both produced an increase in performance but only for the initial 10-15kms. The pollution light comes on. One dealer said there was no problem indicated and another could not get his reader to work because there was no power.
    Don

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    1000+ Posts George 1/8th's Avatar
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    Hi Don,
    to diagnose a C5 you need the Diagbox/Lexia software running on Windows XP on a laptop, or using an emulator such as 'Virtual Machine' on a later computer. The diaxbox software is usually only available to the dealerships. Cracked versions are available with the necessary wiring hardware from China, with the software. From ebay it's about $60- $100. DEPENDING WHICH KIT YOU BUY.
    It takes about 3 hrs to set up the software package, and you have to 'flash' the connector almost every time you use it.
    Your mechanics diagnostic might not work on the C5...the wiring is different. As far as I know there isn't a little hand held OBD unit suitable. The ELM connector system works well, but it can only give you a system read out, not the proper diagnostics with fault codes.
    I don't own a 4 cylinder C5, if you have the pollution light coming on you might have had a misfire, a faulty of fouled sparkplug, or a failed coil pack.
    The Lexia setup described above will tell you which cylinder has misfired. You then replace the sparkplugs, and or the faulty coil pack, then delete the fault codes. Then drive it to see if the fault codes remain absent.
    Don, these cars have a very critical antipollution system. It only takes one misfire to happen for the anti-pollution fault warning to come on. It can be annoying to see that light remaining on. A better system would have been if the manufacturers had a reset switch under the bonnet.
    You could just replace the plugs with new ones, and all the coilpacks and have it running perfectly yet still have that warning light coming on. If you have the ELM system the program OBD SPY can turn off the warning.
    If you use the Lexia system you get a lot more specific information and codes.
    If you clear the codes but don't fix anything, they will come back. If you replace the parts and fix the problem, then clear the codes, the light should stay off.
    Good luck.
    Last edited by George 1/8th; 5th March 2016 at 07:49 PM.

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    Now go make me a sandwich Hotrodelectric's Avatar
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    One dealer said there was no problem indicated and another could not get his reader to work because there was no power.


    One thing I would do is, if you can ( I know you might be a little limited there in Tassie) is find a dealer that actually knows the car and it's diagnostics. Failing that, an indie shop who actually cares. There is no excuse for them to tell you either finding without at least an explanation. Both reek of "I don't wanna do the work".
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    I have an electrical notes pdf, written in French, which puts power to the prise diagnostic (pin 16) coming from the body computer on green channel 10 of the computer.

    I'd expect power for what amounts to a computer port to come from the computer, so that makes sense.
    Last edited by seasink; 5th March 2016 at 09:05 PM.

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    In no order I suggest:

    • Find a person with the correct gear, or buy/learn it yourself. A generic reader will either give you limited results, or sometimes red herrings.
    • Avoid playing "Parts Roulette". It's costly and limited in accuracy, as you're finding.
    • Don't trust the computer 100%. A computerised car does not exclude items of physical failure, such as stripped gears in a throttle body motor, or oxidised wiring, or sticking handbrake cables.

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    1000+ Posts Ken W's Avatar
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    You need to find someone with a Lexia/Diagbox system or similar that doesn't need power from the OBD socket. Surely someone in the Citroen Club of Tassie who lives in Hobart will have one.

    Another possibility is to disconnect the battery for a night or see if you can reset the BSI so it might repower the line to the OBD Socket. Can someone point to a sure fire way to reset a BSI?

    Cheers, Ken

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    Quote Originally Posted by Ken W View Post
    You need to find someone with a Lexia/Diagbox system or similar that doesn't need power from the OBD socket. Surely someone in the Citroen Club of Tassie who lives in Hobart will have one.

    Another possibility is to disconnect the battery for a night or see if you can reset the BSI so it might repower the line to the OBD Socket. Can someone point to a sure fire way to reset a BSI?

    Cheers, Ken
    Yes I bought a Lexia and we can not get it to activate. I was even prepared to buy a more expensive unit and my challenge to the seller was if it gives a reading I will buy it. It confirmed that there was no power so I did not get to buy it. I had firstly changed the battery, plugs and coils on the advice of the garage - a Citroen expert... Made no difference. The other bits did improve but not fixed. I will try and trace that wire back and see if it is active at the source. Every time I changed a censor i disconected the battery to allow the computer to reset. The hoses leading into the airintake have been checked as well. I have been in a couple of "normal" cars the last few days and miss the citroen so I will persevere if I can

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    Hi,
    If you need a quick fix then just put power direct from the battery to that wire to the pin and get your readings. It is normally always powered. I could plug my generic scanner in and it powered up straight away and you set the menu before switching on the ignition.
    I do believe that the handbook lists a fuse that includes the diagnostic port along with something else ?? Memory ?? I do not assume the power would come from the computer. Why ?
    You can look on the Citroen web site for wiring diagrams. Vin specific too !
    Jaahn

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    Looking at the circumstances as provided, the issue commences when the car has reached what's probably a stable operating temperature. At this point, the thermostat will be moderating coolant flow and the ECU in closed loop mode.

    You can buy male and female ODB-II "tails" off the internet quite cheaply, if you want to play further these can be of use in making a breakout box.

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    Quote Originally Posted by addo View Post
    Looking at the circumstances as provided, the issue commences when the car has reached what's probably a stable operating temperature. At this point, the thermostat will be moderating coolant flow and the ECU in closed loop mode.

    You can buy male and female ODB-II "tails" off the internet quite cheaply, if you want to play further these can be of use in making a breakout box.
    Please excuse me for sounding or actually being obtuse - I never kept up with the development of electronics, choosing I guess, just to marvel at the (normally) reliable performance that is extracted from a modest engine these days.
    So if the ECU is in closed loop mode does that mean the diagnostic may not be available and may come on stream if you let everything cool down?
    Do I go looking for an OBD tail that fits into the diagnostic plug?
    When the engine reaches temperature and the ECU is in closed down - could it be missing out somehow on getting the signals into it and if I learn how to use a break out box should that be able to determin and identify it?

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    Quote Originally Posted by jaahn View Post
    Hi,
    If you need a quick fix then just put power direct from the battery to that wire to the pin and get your readings. It is normally always powered. I could plug my generic scanner in and it powered up straight away and you set the menu before switching on the ignition.
    I do believe that the handbook lists a fuse that includes the diagnostic port along with something else ?? Memory ?? I do not assume the power would come from the computer. Why ?
    You can look on the Citroen web site for wiring diagrams. Vin specific too !
    Jaahn
    I did have a go at following the wiring diagram but quickly got lost.....

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    Closed Loop and Open Loop are the two main "modes" of ECU operation. A Lexia or Diagbox machine can read operating (live) parameters in either mode or with the engine stopped.

    Basically, in Open Loop, the ECU considers it is not yet stabilised. It frequently ignores the oxygen sensors altogether, going on MAP/MAF readings, knock sensing, throttle position, intake air temperature, coolant temperature to decide the amount of fuel injected (ie, injector open time at fixed fuel rail pressure).

    In closed loop, the ECU decides based on coolant temperature that the engine is "warm" and proceeds to trim the fuel mixture by relying on the first oxygen sensor as a measure of richness or leanness. The second oxygen sensor is a checking device to make sure the catalytic converter is operating correctly.

    Don't take this the wrong way, but you picked one heck of a place to own a slightly cantankerous French car. Maybe one of the FCCT members on here can comment on whether there are any tech-savvy C5 owners within striking distance.
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    Quote Originally Posted by C5challenge View Post
    I did have a go at following the wiring diagram but quickly got lost.....
    Don't feel bad. Diagrams are notoriously difficult to read. Some types, like the later GM flow-chart style are easier to use than others. Some, like the '80's Japanese are almost impossible. It sometimes helps to take a sharpened object, like a pencil and just slowly trace over the line lightly from/to, noting breaks and splices along the way.
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    Quote Originally Posted by addo View Post
    Closed Loop and Open Loop are the two main "modes" of ECU operation. A Lexia or Diagbox machine can read operating (live) parameters in either mode or with the engine stopped.

    Basically, in Open Loop, the ECU considers it is not yet stabilised. It frequently ignores the oxygen sensors altogether, going on MAP/MAF readings, knock sensing, throttle position, intake air temperature, coolant temperature to decide the amount of fuel injected (ie, injector open time at fixed fuel rail pressure).

    In closed loop, the ECU decides based on coolant temperature that the engine is "warm" and proceeds to trim the fuel mixture by relying on the first oxygen sensor as a measure of richness or leanness. The second oxygen sensor is a checking device to make sure the catalytic converter is operating correctly.

    Don't take this the wrong way, but you picked one heck of a place to own a slightly cantankerous French car. Maybe one of the FCCT members on here can comment on whether there are any tech-savvy C5 owners within striking distance.
    That is the best, most concise description of open/closed loop I've seen in a long time.
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    That's very kind.

    I tried to phrase it so the known elements of sensing/control could be "seen" in their capacity to contribute - and perhaps help narrow down the likely culprits.

    The main benefit I can see in a breakout box, is not only can you view parameters on a Lexia, but you can run a scope off a signal, for example, or apply a live feed where there isn't currently one, or augment the earthing to test it.

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    Quote Originally Posted by addo View Post
    Closed Loop and Open Loop are the two main "modes" of ECU operation. A Lexia or Diagbox machine can read operating (live) parameters in either mode or with the engine stopped.

    Basically, in Open Loop, the ECU considers it is not yet stabilised. It frequently ignores the oxygen sensors altogether, going on MAP/MAF readings, knock sensing, throttle position, intake air temperature, coolant temperature to decide the amount of fuel injected (ie, injector open time at fixed fuel rail pressure).

    In closed loop, the ECU decides based on coolant temperature that the engine is "warm" and proceeds to trim the fuel mixture by relying on the first oxygen sensor as a measure of richness or leanness. The second oxygen sensor is a checking device to make sure the catalytic converter is operating correctly.

    Don't take this the wrong way, but you picked one heck of a place to own a slightly cantankerous French car. Maybe one of the FCCT members on here can comment on whether there are any tech-savvy C5 owners within striking distance.
    So maybe there is a break in the circuit from engine temp censor to the ECU. The dash temp guage and oil temp gauge both seem to be working OK so the censors should be OK. Do you know which the ECU senses - oil temp or water temp?
    On location - well the temp here is mostly benign and the scenery is great and Tassie food is that much better - there are very few and mostly NO flies and if you have a C5 the driving is very nice BUT we are a bit behind in keeping up with technology- I just have to force my mind to do it! You must visit sometime
    See I still have not mastered smilies.....

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    Quote Originally Posted by C5challenge View Post
    So maybe there is a break in the circuit from engine temp censor to the ECU. The dash temp guage and oil temp gauge both seem to be working OK so the censors should be OK. Do you know which the ECU senses - oil temp or water temp?
    On location - well the temp here is mostly benign and the scenery is great and Tassie food is that much better - there are very few and mostly NO flies and if you have a C5 the driving is very nice BUT we are a bit behind in keeping up with technology- I just have to force my mind to do it! You must visit sometime
    See I still have not mastered smilies.....
    Oh it did come up when posted - I am advancing already!

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    The ECU works off water temperature. The one sender in your coolant circuit provides a signal that is digested for both your dash display and ECU control. If it reaches normal operating temperature and stays there, it's reasonable to assume it's OK.

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    I thought I already posted this - the live power pin of the diagnostic port is fed from the body computer. I did look at the French wiring diagram.

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    Quote Originally Posted by C5challenge View Post
    So maybe there is a break in the circuit from engine temp censor to the ECU. The dash temp guage and oil temp gauge both seem to be working OK so the censors should be OK. Do you know which the ECU senses - oil temp or water temp?
    On location - ----sometime
    See I still have not mastered smilies.....
    Hi,
    I do not think you will get far with a fully electronic car like the C5 guessing. If the computer lost a sensor reading then it would log a fault and put up a fault light. This light would not go out till the fault is cleared or goes away AND some number of starts are done. However the fault is still logged in memory.

    You can look at the real time diagnostic output even with a generic scanner. A lexia will tell all, even if it has to be interperated a bit. However only if the port is working correctly. If the power comes from the body computer maybe it is faulty because someone has shorted it or ???? If you supplied power to the pin and the scanner or lexia boots up then it should tell you if the body computer is OK.

    10-15 ks does not sound like it is after " just warming up" to me. That would be 2-3ks.
    Jaahn

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    Hi
    On the EOBD pin connector, number one= ign positive, number sixteen is battery positive, number eleven is data BSI, pin fifteen is data engine management. Fuse 11 on the BSI may be worth a look but I would go for a bad pin crimp on the connector wiring. This data may be or may not be correct for your model. Not hard to check.

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    1000+ Posts George 1/8th's Avatar
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    Hey Don,
    just a thought. No matter how complex or computerised these cars are the basics are still the same. For the engine to run properly you need fuel and spark. If you have changed the plugs and coils and the problem is the same , you might have a fuel pressure problem, a fuel injector problem, or a leak in an air hose. Things you can check without the Lexia.
    BTW.. for the Lexia to work you have to make sure your computer USB recognises and connects with your connector device, and you might have to re-flash the connector as well. I find both of these have to be done every time. Good luck with it. Cheers.

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    Quote Originally Posted by George 1/8th View Post
    Hey Don,
    just a thought. No matter how complex or computerised these cars are the basics are still the same. For the engine to run properly you need fuel and spark. If you have changed the plugs and coils and the problem is the same , you might have a fuel pressure problem, a fuel injector problem, or a leak in an air hose. Things you can check without the Lexia.
    BTW.. for the Lexia to work you have to make sure your computer USB recognises and connects with your connector device, and you might have to re-flash the connector as well. I find both of these have to be done every time. Good luck with it. Cheers.
    I actually started with the fuel system - pressure was OK I put a new pump in about 18months ago and the garage said it was fine - I also had the injectors cleaned - I do not know if they were tested though. The plugs looked even, so we thought they were OK. If the injectors were bad, that I think would show up if I can get the diagnostic tool to work. There is one available in town for $500 that logicar are selling. It would have been worth it if I had bought it to begin with...I have had three computer savvy people have a go at the Lexia - I will pass on your post and see if they can have a go again.
    Don

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    Quote Originally Posted by jaahn View Post
    Hi,
    I do not think you will get far with a fully electronic car like the C5 guessing. If the computer lost a sensor reading then it would log a fault and put up a fault light. This light would not go out till the fault is cleared or goes away AND some number of starts are done. However the fault is still logged in memory.

    You can look at the real time diagnostic output even with a generic scanner. A lexia will tell all, even if it has to be interperated a bit. However only if the port is working correctly. If the power comes from the body computer maybe it is faulty because someone has shorted it or ???? If you supplied power to the pin and the scanner or lexia boots up then it should tell you if the body computer is OK.

    10-15 ks does not sound like it is after " just warming up" to me. That would be 2-3ks.
    Jaahn
    Hi Jaahn,
    I checked the fuses again - surely if it had shorted it would have blown the fuse? If I make it to town today I think I will have to bight the bullet and get a reader that works. If the bloody thing didnt drive so nice I would trade it - nothing available in Tassie at present though.

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    Hi,
    I have sent you a PM.
    Do you know there are more fuses in the engine compartment ! I do not think there is a problem there though as you would see things are not working !
    Jaahn

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