Citroen C5 won't start. Can't use Lexia (easily) in economy mode.
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Thread: Citroen C5 won't start. Can't use Lexia (easily) in economy mode.

  1. #1
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    Default Citroen C5 won't start. Can't use Lexia (easily) in economy mode.

    I've got an '07 C5 2L petrol auto. The other day it started but then stalled as soon as I put it in reverse. I started it again, it stalled when I put it in reverse again, and ever since then it will not start at all. It turns over but it doesn't seem to fire. I suspect the ECU is cutting fuel flow because of an error code.

    So I plugged in my Lexia after having it on a battery charger all week, and the car is in economy mode, so I can't talk to most of the CANbus devices. I can only talk to the injection, suspension and gearbox ECUs. However when I select the injection computer, it asks me to manually select which type of ECU it is. I suspect that's because the BSI can't talk in economy mode to tell Lexia what injection ECU to expect. The top option for a 2.0L with Magnetti Marelli ECU won't connect, but all the others connect with a warning that the data might be invalid if I selected the wrong type of ECU. From any of the other options, I can identify the injection ECU as in this image below. If I look at the fault codes on any other injection ECU than the 2.0L one that won't connect, it shows faults that don't seem right, like the injectors and ignition coil triggers all being shorted to ground. I guess that means the other types of ECU have different pinouts so the one I need is the one that won't connect.
    Citroen C5 won't start. Can't use Lexia (easily) in economy mode.-c5-ecu.jpg

    Since the gearbox ECU only offered two options and I know it's an AL4, I could connect and read codes. It had only the code, "no torque signal input from injection ECU", which the trace XML file says was only logged during the scan. This would mean it had no gearbox codes before the scan, I think, which is odd because a gearbox warning had come up on the dashboard screen since it last had codes cleared.

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    So all in all it seems like Lexia is very difficult to get working with the car in economy mode, but is there any way I can exit economy mode without starting the engine?
    Last edited by Blufires; 22nd July 2018 at 02:29 PM.
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  2. #2
    1000+ Posts garyk's Avatar
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    I really can't offer any expertise, but my experience with the C5s has often been a fault in the relay box.
    Having the Lexia will hopefully assist you, but I've had my own cars, and a friend's, that all had starting problems (or cut out/limp mode) that originated there. "Some say" it is a bad earth there, etc.

    Repair is usually not an option but not too expensive to replace.
    My C5 had an electric intermittent, which stopped being problem (long story) after some special manoeuvres ...!
    Blufires likes this.
    Once upon a time:


    Many R4s (incl. fourgonnette), R5LS, R16TS.


    GS 1015, 1220, sedans and wagons.
    CX 2200, 2400.
    ID 1966, 1969, DS21H, DSpecial, DS23 Pallas.
    C5 2002, 2004 petrol and diesel.
    D Special 1974
    Xantia Activa 1998 (look out Gulargambone)
    GS 5 speed sedan (what a tale)
    1986 2CV6
    CX25GTi 1985 auto
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    And now:

    C5 2.2 HDI 2005 wagon
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  3. #3
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    Are you referring to the fuse box under the bonnet near the left hand side strut tower? I've already had the air conditioner fuse in that location have such a poor connection that it arced and melted the plastic head of the fuse down into the holder, without the fuse even blowing.
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    Computer economy mode disappears when the battery is fully charged. Why not put another battery in parallel, as in a jump start?

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    Seasink, I thought it was a 30 minute timer and then the car will stay in economy mode until it gets started? I can put it on a battery charger to bring it up to 14.5v since it's on my driveway. I already did that, but left it a few days before using Lexia, so I guess I'll put it back on charge now.

    In the Lexia software I was able to do actuator tests on the injection ECU such as turning on the cooling fans etc. When I did the actuator test for the fuel pump, I heard the relay click but not the pump priming from under the back seat. I assumed it was just not being powered because I was in economy mode, but now I'm thinking that might be it. Perhaps my problem is a burn out pin 11 from the engine bay fuse box, as David S had (and posted this picture). I'll have a look at it tomorrow, and I might run the tests on the injectors etc too just to make sure they all actuate as they should.
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    Quote Originally Posted by Blufires View Post
    Seasink, I thought it was a 30 minute timer and then the car will stay in economy mode until it gets started? I can put it on a battery charger to bring it up to 14.5v since it's on my driveway. I already did that, but left it a few days before using Lexia, so I guess I'll put it back on charge now.

    In the Lexia software I was able to do actuator tests on the injection ECU such as turning on the cooling fans etc. When I did the actuator test for the fuel pump, I heard the relay click but not the pump priming from under the back seat. I assumed it was just not being powered because I was in economy mode, but now I'm thinking that might be it. Perhaps my problem is a burn out pin 11 from the engine bay fuse box, as David S had (and posted this picture). I'll have a look at it tomorrow, and I might run the tests on the injectors etc too just to make sure they all actuate as they should.
    Hi
    Quick test on the fuel pump could be to crank the engine while(someone else) spraying a starting fluid(or petrol) into the air intake. If it kicks and attempts to go while spraying then probably lack of petrol. Caution required
    Check if the pump is actually pumping for several seconds when you switch on the ignition each time, as it should. The pump is under the rear seat, drivers side, large round hatch.
    good luck Jaahn

  7. #7
    1000+ Posts George 1/8th's Avatar
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    Hey Blufires, Lexia is a pig at the best of times. If Citroen didn't make such nice cars I would have deleted them from my driveway years ago. Lexia is the strangest old program, dos based I think, it's a true anachronism and a bastard to use. Good luck with the economy mode. The only way to get out of economy mode that I know of is to run the engine. I know that's no help when you can't start it. The basics still apply...if it won't run it's either no petrol or no spark. If your fuel is pumping it has to be no spark. If you have spark, then there's no petrol. If you can get the RACV to give it a jump start it will at least clear the economy mode.
    It is most likely just a dead battery. I had that happen. It was only a one year old battery. Sure you can recharge an old battery for as long as you like but if it's developed a fault, which you cannot see, it's going to continue to frustrate you. Ask yourself how old is the battery? Start by replacing it with a new one, the CORRECT one too. Even if it costs you over $200.00 it's worth it. Good luck. Cheers. George 1/8th.
    Series one C5 V6 auto.

  8. #8
    1000+ Posts cav91's Avatar
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    I think your on to it with fuel. Check for power at the pump. If not power more than likely the engine fuse box is the problem.

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    So now I've learned that disconnecting the battery will reset economy mode. In regular mode, Lexia can scan all the systems in the car.

    I've confirmed that the fuel pump is getting 12v when I use Lexia to enable it with an actuator test. I'm still not able to start it though. I even tried hooking up another battery directly to the pump and the car still won't start. I even went as far as to remove the pump and run it on a bench for a few seconds and it runs nice and smoothly. The filter was clean but had a tear in the stainless mesh.

    Lexia had this to say. Very odd that it has a fuel pump fault but the pump is getting power and the car won't start even with another battery powering the pump independently.
    Citroen C5 won't start. Can't use Lexia (easily) in economy mode.-fuel-pump-issue.png

    I'm wondering now if there's some kind of continuity check with the fuel pump that won't allow ignition if the pump looks disconnected. Anybody have any experience with this?
    --------------------------------------------------------------
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    Maybe the pump impeller or piston is damaged therefore not creating enough pressure.

    Try the 'start ya bastard' option in the intake like the previous poster suggested.

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    1000+ Posts dmccurtayne's Avatar
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    What faults are in the engine ecu

  12. #12
    1000+ Posts dmccurtayne's Avatar
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    If you have all the faults like injectors coils etc put power down the injection fuse if it starts replace the fuse box part number 6500ck maybe from memory

  13. #13
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    Also a c5 like your should have a rfj 2.0 mm6lpb

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    1000+ Posts Ken W's Avatar
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    What pressure is the Lexia detecting in the HDI fuel rail during cranking? ie Is the HP fuel pump working?

    Is the Lexia reading any faults detected by the Engine ECU? Are you getting electrical pulses at the injectors?

    Ken

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    1000+ Posts dmccurtayne's Avatar
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    Ken w petrol

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    The saga continues. I ordered a replacement 6500ck, but it turns out the replacement is a Delphi unit and the original is a Siemens VDO one. Anyone know if they're interchangeable? My C5 is the base model without HID headlights or headlight washers, so I wouldn't expect there to be missing fuse holders or relays. All the sockets are the same pin count and locations.


    The table showing all the different versions of the fuse box. The weird thing is my car is a 2007 and the replacement was pulled from a 2006 car. Maybe the Siemens unit was swapped in by the car's previous owner? That might explain why the A/C blower fuse (F11) holder melted down previously. Maybe the blower fan is stronger in later cars...
    Last edited by Blufires; 21st September 2018 at 05:34 PM.
    --------------------------------------------------------------
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    Citroen Berlingo 1.4 M
    - two person micro camper & work car.

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    Like you say the replacement unit has the additional features but your model wont have these so just plug in and see if you get spark....thats what I would do😃

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    The new part fits and all functions seem to work. Thanks for the advice everyone.
    dimistyle likes this.
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  19. #19
    Fellow Frogger! dimistyle's Avatar
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    Thats great news, so backward compatible between the 2 manufacturers.
    Easy swap over as well.

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