help disabling the immobiliser on my 1998 Synergie

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Mosser
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help disabling the immobiliser on my 1998 Synergie

Post by Mosser »

I've narrowed my fault down to definitly being and ecu problem, and what looks like an immobiliser fault, but the trouble is that i cannot find out any information on how the immobiliser works or how to disable it

I have tested all the external sensors and they all work ok, but my car wont provide power to the coil or power to the fuel pump and if i jump the ignition/fuel relay to get them running, the ECU then wont provide a timing signal to tell the coil to fire, so it still doesnt work !!

I have been all round the ECU with a logic probe and it basically seems to be active with ttl signals at various points except for the spark and fuel pump output signals, there doesnt appear to be anything wrong with the output transistors either and the coil checks out as good

Does anyone have any info on how the immobiliser works on the Magneti Marelli 8P ECU in my car ?, I assume its a chip in the key read by a coil around the ignition barrel ?, any tests i can do and what output i would expect ?, or is there any way i can bypass the immobiliser section of the ECU ?

I would understand that anyone with this knowledge wouldnt want to post it on a public forum and would appreciate any information however small either in reply to me here, or by email to me at ian (at) Mosser . co . uk

Thanks
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Post by AndersDK »

Mosser - I'm pretty sure you can not disable an immobiliser - for obvious reasons :!:

Your '98 Synergie immobilising setup has got to be the same system as found in Xantiae of same era. Its got nothing to do with the engine management ECU, but is a 'body' computer dealing with immobilising & alarm issues (and enabling/disabling the engine ECU).
I suspect that if you manage to get your engine ECU tested or replaced, you end up exactly in the same state as you are in now : dealing with an immobilised car.

Try a Xantia immobiliser search on the forum. There are lots of postings on this issue which should be food for brains to move you on. There is one thing in particular I suspect could give you problems : the ignition switch key reader coil. This has known to be defective on quite a few occasions.
http://www.citroen-pr.net/catalogues/il ... 24050A.gif
item 1 on the schematic
01 - 6160.48 - AERIAL ELECTRONIC ANTI-THEFT KEY

This 'aerial' is a HF coil initially charging the key chip, which then stores exactly the tiny amount of energy needed to reply with its code, in turn received by the coil.
All your knowledge on electronics fault tracing on this aerial and its cabling would apply !

Hope you've got at least 2 keys for your Synergie ? As it could be one of the key chips defunct. But both keys defunct is unlikely.
If you only have one key, your only other option is to let your main stealer read or test the key, and ask them for further details on a new key.

Hope some of our good brains here on forum can supply further info on the track I've depicted here for solving your problem.
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Post by CitroJim »

Yes, I have that problem. One key works and the other does not.

Mosser, you should have a light on your dash to tell you if your are immobilised. It (on the xantia) looks like a "U" on its side with an arrow thing going into it, a symbolic key in a lock. Also, if the immobiliser fails to read the key it will bleep several times.

The immobilier light will initially light up on ignition on and then go out as soon as the key is successfully read.

The ECU is normally mounted in the steering wheel cowl above the ignition switch. Check the aerial position and connections as Anders advises. Also, I believe that it works on a frequency of 13.56MHz. If you have a receiver capable of tuning to this frequency you should be able to hear it.

Another test of this ECU is that if you switch off and then open a door it will bleep at you to remind you to remove the key.

The only options for unlocking the ECU are thus: Go to your local Cit dealer and ask him for a new key and to program it. You'll need the transponder code for this which if you don't have it (on a plastic card with the handbooks etc but often lost) he can get it via the cars VIN Number, proof of ownership and sums of money. Or, get a specialist to unlock the ECU so that the transponder immobiliser in the car is no longer needed at all.
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Post by CitroJim »

Another possible way to resolve this is to go to a good scrapyard and get an ECU, Transponder and keys and transplant the lot. Trouble is, the scrappies know the value of this stuff and it may be much dearer than going to a Cit dealer and having new keys made and transponders programmed.

I believe that the ECU and Transponder are tied to each other and cannot be used in a mix and match way.

If you go this way, it is possible to remove the transponder chip from one key and transplant it into another key. A delicate job though and easier on an RF plip key than a normal key.
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Post by Mosser »

Thanks for the information, I didnt expect it to take me this long to fix a problem like this and i'm starting to loose the enthusiasm to keep going with this problem now,

and as my wife is nagging me to get it sorted, I may be part exchanging it for something a bit newer fairly soon, but i'm not sure if a dealer will take it as a non runner ?

Whichever way i look at it now, i cant override the immobiliser myself, and the dealer will probably change a few bits and charge me an arm and a leg for doing so, the engine still has the nasty noise comming from the bottom end, which turned out to be the main bearing shell scraping on the crank, I think some new shells and loosening of the massively overtightened cambelt would sort that, but as the central locking has failed too, and the left rear sliding door wont open any more from the inside or outside, I'm thinking that its probably time to call it a day on this car, Its a shame really, as its fully loaded with all the goodies including digital climate control, and it really nice to drive, but i dont think it would be economical to fix it unless i could do it myself :(
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Post by wheeler »

Im pretty sure that the transponder imobiliser does not stop the fuel pump operating, it just stops the injectors operating. if you use an unprogramed key or sheild the key & turn on the ignition you should still hear the fuel pump priming.
From what you say I suspect the injection ECU is at fault (provided that all the live feeds & earths are sound & there is good continuity and no shorts to earth on any comunication wires.)
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Post by Mosser »

The problem is that there is so little information about the immobiliser system available anywhere, quite understandable too i suppose !!, but i really dont know what it should be doing, and the cheapest price i can get the ECU fixed and unlocked is £195 +vat + delivery, I would think that my car is probably worth less than £1000 by now, so if i can get the wife to agree that it can stay a bit longer, i will carry on working on it, but its her that has to walk 2.1 miles to school twice a day to take our son to school, and its her that will probably decide whether i get more time on it or not !!

I will take the ECU apart myself i think now and have a poke about, the problem there is that if i do that and cant fix it, mose ECU repair companies will charge more, or even refuse to work on an ECU that someone has already opened and played about with, If i knew that the £200 spend would fix it, i would do it, but its not guaranteed that it will work after that which is why i am hesitant to send it off
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Post by Mosser »

Wohoo!!, fault found :)

I commenced testing on my ecu myself this morning as i got back replies from 2 companies including BBA-reman that both said they are unable to test and repair MM8P ecu's, so i thought i have nothing to loose by having a go at it myself, I have lent my oscilloscope to someone a while back and cant remember who borrowed it !!, so bought a £15 logic probe and went round the board to find the processor was dead, no clock signal and no active inputs or outputs, so i pressed down on it and it all sprang into life :) , unpon closer inspection, the solder joints on the motorola 6800 series 52 pin plcc processor had minute fractures in them, and pressing down remade them whilst my thumb was on it and it all worked !,

So, now i have the delicate task of resoldering a 52 pin plcc device with a pin spacing of only 0.5 mm :(

Here's hoping i am succesful !, i will know in about an hour or so
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Post by CitroJim »

That is excellent news Mosser!!!! :D :D :D :D

Very well done, quite brilliant 8)
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Post by AndersDK »

Astonishing founding really :!:
1 or 2, maybe a 'few' dry solder joints - but most of the pins on a chip :shock:

Mosser - being an old fart in electronics I'm so pleased to read about you finally have some luck with the Synergie :D
I really honestly believe that you earn yourself the spendings on a micro-tip soldering iron to finally solve the problem. Go mad on Maplin's on-line shop :lol:
(they are not that expensive after all !)

Well done 8)
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Post by Mosser »

Thanks to both of you !, I wouldnt have been able to sort it without your help

It wasnt just that chip that needed resoldering, after i had resoldered it, I connected it up to the car out of its case and it ran fine, so i reassembled it and connected it up again, and it was dead, no amount of pressing on it would get it to run, so out with the logic probe again, to find that there was another, bigger plcc 4 sided chip with exactly the same problem, but it had nearly 20 pins that i could see hairline fractures in under my 9x power eyeglass, so back out with my soldering iron and reflowed all pins on both chips this time, thats about 130 + pins resoldered, tested it out of the box, and it was fine, flexed the board whilst it was running and it was fine, put it back in the box and ran it, and it was fine !, so its all back together now, gave it a run round the block and it was driving like a new car !, the high idle, misfiring, internittent starting are all gone and it is running silky smooth again :) , I even took the wife and kids shopping in it tonight as i was confident it was fixed and it ran perfectly :)

as to me investing in a micro tip soldering iron, i already have a weller soldering station with a huge range of bits !!, I used to work for Harris semiconductors in the repair center so am well versed in reflow work and fault findng electronics :)

Thanks to everyone that helped me with this fix, it took way longer than i expected, but i'm glad i stuck with it and didnt give up :)
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Post by CitroJim »

Even more excellent Mosser :lol: :lol: What a result! I reckon you must be well pleased :P

The best I have ever done with SMD is to swap over a small transistor and they only have three legs :roll:

If your ECU ever fails again then you'll be well able to brew your own Megasquirt replacement with your skills. You may find this link interesting:

http://www.megasquirt.info/

This homebrew ECU is quite popular with the 205GTi lads and they have successfully used it with the XU10J2 Turbo engine. You have all the necessary sensors.
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Post by Mosser »

I am well pleased with the fix, its cost me nothing in the end to sort out !!

I have started to collect some megasquirt bits, i have a ford EDIS coil and some sensors, but never got around to buying the megasquirt itself as they always seem to have a better version in the pipeline that is due imminintly and i kept waiting for that one intead!

I am looking out for a renault 5 gt turbo cheap with a sound body, but engine problems that i can sort out myself and then convert to efi and put a megasquirt kit on it, It will be a nice project for the summer :)
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Post by lolingram »

I would just add my humble congrats Moser. I install SAT/TV in S France, and have on occasion mended double sided circuit boards, but what you have done is at least an order of magnitude higher... Chapeau!
I am well pleased with the fix, its cost me nothing in the end to sort out !!
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Re: help disabling the immobiliser on my 1998 Synergie

Post by Wearde quay1 »

I am looking for advice about an Alarm/immobiliser as well on a Peugeot 806 Eurovan.
Disconnecting and re-charging the battery seems to have re-set these. I had not been using the original ignition key and therefore the alarm was not routinely set.
(The model pre-dates the system where security is exclusively on the key. Instead, there was a numeric-pad and a separate, key set, alarm.
Starting the vehicle became a problem recently.
Symptoms indicated starter motor or battery, although the battery was not old.
Installing a new battery led to the alarm going off and the headlights flashing persistently (After re-fitting the older battery, the h/lights flashed about six times and then stayed off until a door was opened).
With the new battery, the original key does not now seem to stop headlights flashing and the interior alarm indicator switch (which the H/B says de-activates the alarm) is continuing to flash, suggesting alarm set.
Although I still have the handbook, which includes advice about tackling alarm issues, I would like to disable it.
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