S Type security back up sounder and immobiliser

[plaviator]

I know that there is an old post about this but I have a similar problem. The difference in my case is that the main car battery is new and fully charged and also not only does this alarm sound but it actually does immobilise the car. the car is a 2005 S type 2.7D

So the situation is this: one hot day I heard the beeping noise from under the bonnet of the car. This was not the horn but a high pitched beeping which I had never heard before. Even though I unlocked the car with the fob, it still continued to beep and when I tried to start the engine, although it turned over, it would not start. I then disconnected the main battery and the alarm stopped. After 10 minutes I reconnected the battery but although the alarm did not sound, the engine still would not start.

I then connected my iCarsoft diagnostics and it came up with 7 faults on the engine, including crankshaft position sensor, MAF sensors, Turbo boost solenoid, No 6 cylinder injector and others. This was without the engine running and had previously run perfectly. I then cleared all faults and the engine started normally. When I then ran the diagnostics there were no DTC faults.

Now, if I leave the car locked overnight, the immobiliser has always activated in the morning. Whether the alarm sounded I don't know as I can't hear it from my bedroom. If I leave the car unlocked then it is fine in the morning.

Can anyone advise me as it appears that I cannot access the immobiliser with the iCarsoft LR V3.0

[JustBadly]

Only SDD/IDS can access immobiliser faults. Then you can remove the battery sounder and strike it off the dealer options. A fault signal from the battery sounder will trigger the main alarm. Diagnostics will tell you if a module is playing up, all in all recommended. Until then you are doing as much as you can.

[plaviator]

The situation has worsened now as if I try to start the car in the morning, it spins over like crazy but won't start. If I then cycle the ignition on and off about 10 times then it will start straight away.

My thinking was that perhaps the check valve in the tank fuel pump was leaking back but when I removed the delivery pipe from the pump, it was full and the fuel did not disappear from the outlet stub, indicating no leak-back. In any case, with the ignition on, the pump runs continuously so switching the ignition on/off shouldn't be the cure.

This only happened before if I locked the car but now it happens locked or unlocked and depending on the length of time that it has not run determines the number of ignition cycles I have to make. If it is off for an hour then probably only two.

I am still leaning towards a faulty immobiliser but would welcome any constructive comments.

Edited 1 hour ago by plaviator
additions