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I am desperately searching your help and advise:
I own my Turbo R ´91 RHD VIN SCBZR04A5MCH35051 since 8 years now, however, I only had a chance to drive it occasionally. Many times in the past, I had removed the battery and connected it to my Ctek charger. Never had problems reinstalling the battery.
This time, putting the battery back into the Bentley, an alarm sounded, which I even didn’t know I have. After going through many of the respective posts here, I confirm, that I have the Alarm ECU under the top roll. I have taken it out and confirmed, that the installed battery was dead. No leak, no damage to the board. So, I have replaced the battery with a new one, put it back to the car, connected the car’s battery – and: the alarm siren under the right hand front wing went on: beep beep beep …
The switch in the glove compartment is in ‚isolate‘ position
I don’t have (never had) the Remote Control ECU in the luggage compartment behind the right hand side panel. There is only a wire loom and two connectors connected to each other, very similar to these of the Alarm ECU under the top roll. Neither do I have any control key fobs.
Interior lights are on, I can switch on the head lights, I hear the fuel pump priming when I turn the ignition key, I can hear the gear actuator working when moving the lever, however, the starter doesn’t move, no noise of any relay, no nothing. I have the resistance of the key when tuning to star, but nothing happens.
I have checked and cleaned all fuses and relay contacs.
Next, I have bridged the two white / yellow cables of the Alarm ECU, hoping this would bridge the burglar immobilzer – obviously, it did not ?

My questions:
  • how do / can I disarm the factory installed burglar system without remote control key fob ?
    I could disconnect the siren wiring – this, however, would not solve the immobilation of the starter and bridging of the white / yellow wires going in and out of the Alarm ECU didn’t either.

  • why this alarm / immobilisation of the starter never happend in the past ?

  • which wire goeas from the Alarm ECU tot he siren – can I disable it ? So, I could continue trying whithout removing the siren from under the wing and without enoying the entire neighbourhood.

Your feedback would be greatly appreciated.
 

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Next, I have bridged the two white / yellow cables of the Alarm ECU, hoping this would bridge the burglar immobilzer – obviously, it did not ?

My questions:
  • how do / can I disarm the factory installed burglar system without remote control key fob ?
    I could disconnect the siren wiring – this, however, would not solve the immobilation of the starter and bridging of the white / yellow wires going in and out of the Alarm ECU didn’t either.

  • why this alarm / immobilisation of the starter never happend in the past ?

  • which wire goeas from the Alarm ECU tot he siren – can I disable it ? So, I could continue trying whithout removing the siren from under the wing and without enoying the entire neighbourhood.
You started in a good way. So, try to disconnect fully Alarm ECU and then bridge separately white-yellow pair and slate-pink pair at the connector (white-yellow wires are for starter circuit and slate-pink for central-lock). The burglar immobilizer will be fully omitted.

The siren is normally connected to black-yellow and brown-red wires. People at forum wrote, that siren has build-in its own ECU with battery. If it still beeps after disconnecting alarm ECU, maybe siren battery should unload itself... However I'm not sure if information about battery concerns 90-91 cars or newer (in later cars the alarm was completely another, more complicated in type).

In manual is stated that alarm can be disarmed only with remote control. On the diagram there are is only one "unknown" wire from RC ECU in the trunk to alarm ECU that potentially can do it (yellow-pink), however I'm not sure what signal should be there provided (just 12V??? continuously?? only impulse?? modulated?? a ground?!), but it is sure, that to disable alarm other conditions should be fulfilled like closed doors, trunk etc.

PS. With my car not only did I get fob, but even alarm ECU :D I did not fixed it, just switched to other, modern solutions by myself :geek:
 

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Discussion Starter #3
You started in a good way. So, try to disconnect fully Alarm ECU and then bridge separately white-yellow pair and slate-pink pair at the connector. The burglar immobilizer will be fully omitted.

The siren is normally connected to black-yellow and brown-red wires. People at forum wrote, that siren has build-in its own ECU with battery. If it still beeps after disconnecting alarm ECU, maybe siren battery should unload itself... However I'm not sure if information about battery concerns 90-91 cars or newer (in later cars the alarm was completely another, more complicated in type).

In manual is stated that alarm can be disarmed only with remote control. On the diagram there are only one "unknown" wire from RC ECU in the trunk to alarm ECU that potentially can do it (yellow-pink), however I'm not sure what signal should be there provided (just 12V??? continuously?? only impulse?? modulated??), but it is sure, that to disable alarm other conditions should be fulfilled like closed doors, trunk etc.

PS. With my car not only did I get fob, but even alarm ECU :D I did not fixed it, just switched to other, modern solutions by myself :geek:
I am so grateful for your fast and constructive reply. I will apply the recommended measures and report back.
Have a nice season holiday
 
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