Saxo Immobiliser

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dodgydino
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Saxo Immobiliser

Post by dodgydino »

98 Saxo with a 1 ltr engine, The car will suddenly cut out for no apparent reason, When trying to restart the car the key sign is lit on the dash indicating the immobiliser. Trying to restart has no joy but if left for an hour or so to cool down then it will start. I was told it might be the transponder aerial around the key so i put on a new one but this hasnt helped. Also when getting out of the car there used to be some audable beeps which i presumed was the immobilser setting it doesnt now do this. Ive spoken to an auto electrician who doesnt tend to think it will be an immobiliser problem because he says it only reads the key when first put in the ignition. Ive since put a crankshaft sensor on because someone suggested this but to no avail. When its cut out i checked to see if there was a spark at the plug which there wasnt and i also checked to see if any fuel was being pumped into the carb which there wasnt. Im told this points to the immobiliser, Does anyone know if the immobiliser could set itself this way and why when the engine is cold the immobiliser disarms itself with no problems also is there a quick fix or any suggestions on how to solve it.
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AndersDK
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Post by AndersDK »

The immobiliser has nothing to do with the engine management - except for one important role : it will not allow the engine management computer to start.

So please stop forking out any more money on engine sensors.

The most common problem is the key transponder "aerial" which is a simple transmitter/receiver coil. Since this has been replaced, its very unlikely the problem still lies here.

I'd say you should try get the fault codes read out, as they more than likely can give you pointers to the problem. There will be no messages like "connector a5b faulty" or such like. You'd always have to investigate the fault closer to find the cause, being it a loose wire, defective connector, corroded chassispoint, defective sensor etc. etc..
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wheeler
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Post by wheeler »

i am 99% sure this will have nothing at all to do with the imobiliser, this would not cause the car to cut out, just cause a starting problem.
From what you say i would be looking at the double injection relay located underneath the injection ECU. you will need an engine management system wiring diagram & check the feeds going in & out or the relay when the fault occurs.
dodgydino
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Post by dodgydino »

Just an update, At the weekend i decided to take off the immobiliser and since then i havent had any issues. I know its still early days but its the longest its run since i had the car.
Wheeler, I was thinking along the same lines with regards not being the immobiliser but the only thing that puzzled me was the fact that the immobiliser light was showing on the dash!!
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Post by wheeler »

how did you take off the imobiliser ?
the key symbol can illuminate if the ECU cant comunicate with the imobiliser control unit, this can happen if the ECU isnt being powered up.
dodgydino
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Post by dodgydino »

I took the imobiliser off by starting the car then removing the transponder around the keyhole, Then i removed the black box. Then turned off the car. Now i dont get a click noise from the ECU after about 10 seconds when the ignition has been turned off. I was told on various forums and by many people that it wasnt possible but ive removed mine. Its been a week now since its been removed and ive had no problems, The longest it had run before was 2 days. :lol:
I dont think it was soley an imobliser problem, Like ive said before on initial startup the car started fine and never failed to recognise the key but after being run for a while it would then show an imobilser problem by illuminating the key symbol on the dash. It seems like something gets warm then breaks down and the enables the imobiliser and doesnt switch off or recognise the key until the car cools down.
Anyway its still early days but so far so good.
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Post by CitroJim »

dodgydino wrote:I took the imobiliser off by starting the car then removing the transponder around the keyhole, Then i removed the black box. Then turned off the car.
That's rather interesting and useful to know :wink: That technique always worked with the old keypad immobiliser but that's the first time I've heard it will work with the key transponder type.

Thanks for that, as I say, jolly useful information!
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Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
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Post by wheeler »

You dont need to disconnect the reciver round the ign barrell as its only an aerial. it works on the same principal as the keypads, if the unit cant comunicate with the ECU then it cant lock. this method is only any use to the saxo, early dispatches & early berlingos as the imobiliser 'black box' is solely for the imobiliser. xantias & early xsaras the black box (CPH) also controls loads of other features. on later multiplexed cars the BSI takes the place of the CPH so obviously this cant be disconnected.
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Post by dodgydino »

Wheeler, My only concern is if the battery has to be disconnected. Will it just be a matter of connecting the transponder and the black box again to restart the car then going through my original procedure or will it some how confuse the ECU in some way and not allow me to start the car. Or will the ECU save its settings and remember how things were before the battery was disconnected. Dont know if youre still with me but if you are what do you think. :?
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