Immobiliser Replacement

There are two types of TVR out there; those that have had the original immobiliser replaced already, and those that haven’t – yet.
We’re not talking “dodgy TVR electrics” here. These immobilisers were warrantied for 7 years- these cars are 20+ years old now. So actually, they’ve done quite well!

Warning signs your Immobiliser is faulty

The general consensus is, these original units don’t just suddenly die completely; they die a slow death, and as such there are warning signs. The symptoms mine was failing, was that the starter was not engaging. I would hear the fuel pump prime, but on pressing the start button.. nothing would happen. It would take a few attempts, and then it would suddenly come back to life. It only seemed to happen on a cold-start.
Hearing the fuel pump prime each time led me to misdiagnose this as a starter motor problem. I now have a new starter motor, plus a perfectly working spare. ?
So how do you know if it’s the immobiliser at fault?- it’s not easy. There are 3 separate systems controlled- ignition, fuel pump and starter motor. The starter motor is usually the first to go due to it having the highest load through it.

My advice: at the slightest sign of trouble, get it replaced- it’s just a matter of time anyway.

21st Century Immobiliser and Alarm

There aren’t that many people who specialise in replacing these immobilisers in TVRs, but I was lucky enough to catch Carl Baker while he was in the UK.
So what does the new one do?

  • It has a 50% reduction in parasitic battery drain – in other words you can go on holiday for 2 weeks, and not come back to a flat battery.
  • It has a proximity sensor, so that when you are in range of the car, the car is not immobilised- meaning you just press the start button- no faffing around disarming or rushing to beat the time limit before it arms again.
    It’s smart too- the proximity sensor will go to sleep if it hasn’t moved for a while- so if your keys resting place in the house happen to be in range of the car, all is good.
  • There is a button on the remote to open the boot.

It’s like a modern car!

Old on the left, new on the right. (Serial numbers etc obfuscated)
Side topic: what do you make of the scribble on the fibreglass panel?
These cave drawings & scribbles are quite common. Builders from the factory often signed their name, or sometimes left a cave-drawing. Someones initial maybe? or were they interrupted while drawing something else?

4 thoughts on “Immobiliser Replacement

  1. Peter Manewell

    Interesting report about immobiliser faults. My cerbera has similar symptoms which started recently. Today I could not open to door. My thinking was that the battery had failed but may be its the immobiliser. I would appreciate some advice on where to go to for a replacement.

    1. admin Post author

      The simplest/quickest possible solution is to replace the battery. If it hasn’t been replaced in a while, you can do no harm by replacing it.

      If that doesn’t solve it, maybe the door module in the boot is fried- they’re not easy to find a replacement- maybe a fellow local Cerbera owner will let you plug theirs in to see if it solves the problem.

      Lastly, yes maybe immobiliser- for this there’s little a DIY-er can do to work around that, but there are specialists out there than help you temporarily bypass it.

      If you need any contacts, let me know.
      Good luck!

  2. Peter Manewell

    Thought I’d sorted the car but today I backed the car out of the garage and turned it off for 20 minutes and now it will not fire. I can hear the fuel pump though so even more sure its the immobiliser that is u/s. Names / contact details of someone who can get this issue sorted or probably better still get me a new modern replacement would be appreciated.

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