Strange immobiliser problem?

[wideboyno1]

Hi all,

For a couple of weeks now my C5 has occasionally on start-up given the odd fault message such as 'ESP/ASR not functioning' which would immediately go off never to appear again all day.Over the last few days this has been joined by 'Immobiliser Fault' (or something similar) and has at times been difficult to start.Yesterday it was worse than ever and took 10-12 cycles of locking/unlocking the doors with the fob etc before i finally got it going.Every time it wouldn't go i noticed that if you turned the igniton on you didn't hear the fuel pump whirring.I knew it was going to start when on the umpteenth time i heard it and lo and behold it went first time.
Immediately took it to local indy who suggested a new battery even though my old one (2 years old) was cranking fine.On other C5s i've seen what low voltage can do and some of the errors it chucks up so didn't have a problem changing it and got a brand new Exide.
However,this morning,same old story.Took 20 mins for the car to decide it wanted to set the fuel pump in motion and once it did that it started first time and should now be ok all day.The problem seems to arise when the car is left for any longish period of time and especially overnight.
Had my lexia on it and nothing unusal popping up apart from the regular egr message which has been there virtually since i got the car.I normally just clear it every few weeks when the service ligh comes on but apart from that nothing new.
Did wonder whether remote batteries were maybe low but tried spare and that is still the same.

At a bit of a loss........any ideas?

[wheeler]

If you cant hear the fuel pump priming Then i'd start there, see if there is 12v going to the pump, if there is then it will likley be a faulty fuel pump, if there isnt then probably a poor connection at the under bonnet fusebox.
The random warning messages are most likley to be due to low battery voltage with the continued cranking. The immobiliser on this car does not stop the fuel pump operating and the remote batteries dont have anything to do with the immobiliser either.
If it is a faulty in tank fuel pump then thumping the bottom of the fuel tank with your hand while someone tries to start it normally (temporarily) kicks the pump back into life.

[wideboyno1]

Hi wheeler,

Fuel pump failure was my first thought but my indy assures me that this is rare and that the immobiliser does stop it operating.
Will check all connections and see if i can find anything obvious.The main frustration is that after the first successful start the car will then start ok all day every time.It's only when left for a while that this problem comes back.....very strange.
As for the random messages i totally agree about the low voltage hence why i put a brand new battery on.
Cheers for the advice,

[wideboyno1]

Just back from another visit to my indy.Seems to think it is now one of 2 things...either fuel pump sticking or the transponder ariel needs replacing.
Been to main stealers and was amazed when they said the ariel was only about a fiver or so.None on shelf so has to be ordered in but still surprising for Citroen.Back to normal again though when they told me the price of pump..£193.62! Apparently GSF come in at around the £100 mark for the same thing but not been to have a nose yet.
Similar to what Wheeler suggested i've got to wait until tomorrow morning then if the pump doesn't prime move rear seats forward and take off black circular plastic cover and give the pump a couple of taps to see if it frees it up.Here's hoping it's not that and a fivers worth of ariel will sort it.

On an unrelated note i also need a replacement rd3 cd player as mine has a disc stuck and just constantly clicks.Obviously going to get one from a scrappy or ebay but Citroen kindly offered to order me one in for £271! If anyone has one just send me a pm and hopefully we can sort something out.

[wheeler]

Hi wheeler,

Fuel pump failure was my first thought but my indy assures me that this is rare and that the immobiliser does stop it operating.

The immobiliser doesn't inhibit the in tank fuel pump, it just stops the injectors firing. I wouldnt say pump failure on the C5 is majorly common but its certainly not rare.

[wideboyno1]

Well last night and again this morning it failed to start first time...no priming of the fuel pump so gave it a good whack from above and below which didn't magically spark it into life.
I then just tried turning the ignition of and on and after doing this for a while i heard the pump kick in and it started straight away.Am i right in thinking that this points to the transponder ariel needing replacement? At the price quoted yesterday it may just be worth doing anyway...i assume it's just a cowel off job and straight swap out?

Cheers,

[dnsey]

I would have thought that a problem with the transponder would have brought up something like 'immobiliser fault' on the display.

[Mandrake]

I agree, a transponder not working (or not matching the car) would bring up some kind of warning on the dashboard - on a Xantia the orange key symbol light which normally flicks on briefly would instead stay on, on a C5 it would probably be a textual warning, but there would be SOME warning.

wideboyno1: If you've already put a Lexia on the car and found no faults its not the transponder - a failure of the transponder during an attempt to start IS logged as a fault code in the BSI (or CPH in a Xantia) so if there are no such fault codes advising lack of communication with the transponder in the key it is definitely NOT a transponder antenna fault, and very likely not an immobilizer problem.

Another way to test this which is actually the Citroen recommended test method is to fashion a small metal shield the shape of a funnel with its stalk missing and a hole just big enough for the key to poke through, (a small oil funnel with the stalk cut off would be perfect) which slips over the key - the idea being that it allows you to insert the key and turn it, but the RF signal between the transponder antenna and the transponder in the key is blocked. If you do such a test it should deliberately provoke a transponder communication fault which will be logged by the BSI and prevent the engine starting with a warning on the dash.

If this test does just that, you can be absolutely certain that your current issue is NOT a transponder issue, and see for yourself the exact symptoms of lack of transponder communication.

By the way, I believe your indy is wrong about the immobilizer stopping the fuel pump. The following is lifted directly from C5 Mk1 documentation regarding the immobilizer:

1. Presentation
The second generation engine immobiliser (ADC2) immobilises the vehicle by electronically locking the engine management ECU :
The injection and ignition systems do not operate (petrol engines)
The injection and injection advance systems do not operate (diesel engines)

No mention of fuel pump. I suppose you could argue that the fuel pump is part of the "injection system" however I interpret the above to mean the injector firing (and ignition firing on a petrol engine) only.

I really don't think you're looking at an immobilizer problem, I would be going back to basics and measuring the voltage to the fuel pump AT the pump when the symptoms are present. If there is 12v present but the pump is not running you've found a faulty pump. (Although check the connectors aren't corroded etc first)

Remember the pump won't run continuously when the engine is stopped to prevent draining the battery (they use about 10 amps) it will come on for 3-4 seconds when you first turn the key on after the car has stood for a long time, however it will then not come on again until you crank the engine, so you'll need to measure the voltage while someone cranks the engine.

If you have no voltage trace the wiring back to the fuel pump relay and check the inputs and outputs of that relay and maybe try cleaning the contacts on the relay if you haven't yet...

[wideboyno1]

Wow,thanks for that detailed reply Mandrake.
Before I changed the battery I did have an immobiliser fault message come up on the display but since I swapped it for a new one it hasn't appeared again although I do still occasionally get the error beeps but no message.
Definitely worth looking into what you suggest but I may just swap out the transponder aerial anyway..for the sake of a few quid it seems daft not to.If that doesn't do the trick then i'm inclined to agree that the pump really does have to be at fault.
One curious thing that did happen last night was that I was driving along and all of a sudden 'esp/asr not functioning' came up on display along with the usual beeps and then the car just cut out.Tried to restart and got 'anti pollution fault' thrown in for good measure to but it did fire up and has been ok since.Went to it this morning and it fired 1st time and drove flawlessly for 50 miles.I did wonder to myself if somehow the immobiliser had cut in whilst driving and that's why it stopped but my knowledge ends at oil and filter changes really so probably best for me not to dwell on these things!

[wheeler]

The immobiliser cant activate when the engine is running, It can only prevent initial starting. If you unplug the transponder aerial when the engine is running & break the head of the key off to remove the transponder chip the engine will still stay running, it just wont start again the next time you switch it off.
Yes, if the key is not recognised & the immobiliser was preventing it starting you would get a warning light/message every time it failed to start.
Just to reiterate the transponder immobiliser on this car does not prevent the fuel pump in the tank operating.

[Mandrake]

Given that the fuel pump is known not to run sometimes preventing starting (whether its the pump or the voltage supply as yet unknown) the car cutting out while driving and then reporting "anti pollution fault" afterwards does sound like the fuel pump stopped working during driving causing the engine to splutter to a halt a few seconds later... as wheeler says the immobilizer can't stop the engine once its already running. All it does is "unlock" the ECU when you start the engine. It stays unlocked until the ignition has been turned off for 10 seconds at which time it locks again.

It's either the pump failing or the voltage to the pump failing...hopefully the latter as a relay or wiring repair is cheap and easy to fix once found while a pump is expensive!

[wheeler]

It's either the pump failing or the voltage to the pump failing...hopefully the latter as a relay or wiring repair is cheap and easy to fix once found while a pump is expensive!

Unfortunately the fuel pump relay is an integral part of the under bonnet fusebox & not a seperate component so not such a cheap fix.
If the pump is loosing its power supply the usual cause of this on the C5 is a burnt out connection on the grey connector of the under bonnet fusebox.

[wideboyno1]

Thanks guys,it would seem then that as usual it's not going to be a simple,cheap fix.Years of owning Xantias and C5s should have really already told me that!

I fear that wheeler might be correct.Had a look at the fuse box (hopefully then right one!) and pulled the grey connector off.All the connections look ok apart from number 11.Does this look like it could be the problem and if so what is the next step?

As for the transponder ariel i've ordered it anyway and should get it tomorrow.Had a game getting the bottom cowel off but then could see how easy it was to just unclip but isn't the end where it plugs in bloody difficult to unclip.Found myself twisting in all sorts of shapes to get a small flat screwdriver in to free it.Anyway,all back together now and got it to fire eventually but tomorrows another day.It really does look like the wiring to or the actual pump sadly.

Thanks again in advance for the help.

[Ben82]

Looking at the wiring diagram (note: using my very very basic knowledge).. it looks like pins 11 and 12 are linked with Fuse F2, which is the "Fuel Gauge Pump". That does look nasty, does the other part (i.e the actual pin) look in tact?

[wheeler]

Thats exactly what your problem is, pin 11 is the output to the fuel pump. You can get replacement terminals (Citroen part number 6542TV) Not expensive but you may need to buy a bag of 20. You can remove the terminal from the block, cut the old terminal off & fit a new terminal with a new piece of wire so the original is not streched. Also clean the pin in the fusebox with a small file.