This may have been covered previously but I can’t find the answer. I would like to install a battery isolating switch on my 2013 Plus 4. The battery is located near the rear axle and the switch will go on the rear bulkhead between the seats. The reason for the installation is partly for a crude security measure against theft and mostly to isolate the battery when working on the car.

My question concerns the lack of power to the alarm and to the ECU when the battery is isolated. Clearly the alarm wouldn’t work and the ECU may lose its “learnt” mode. Is it therefore sensible to bypass the switch with a flyer wire with a fuse of small capacity to retain some power to the alarm and ECU but any attempt to start the car would blow the fuse?

Any advise would be much appreciated.
Bob.

My T16 +4 had exactly that plus power for the clock

I believe battery isolation switches were primarily fitted to rapidly isolate the battery in the event of fire on a competition car, and hence have a universal key?
If I were a professional sports car thief, its the one item I would carry in my pocket!

If theft is the main concern, I would look to installing a simple isolating switch which is wired to prevent the fuel pump from operating. Simple access to intercept the white/pink wire to the inertia switch that is mounted on the near side bulkhead adjacent to the coolant tank, would be a very simple and easy job to do. You could position the switch wherever you like, say under the dash with just a short run of wires.

I like Deejay’s fuel pump switch but not so sure about the small fuse with the isolator!

If the car is a Duratec and unless you have fitted one yourself I don’t think it will have an alarm so you would only be powering the immobiliser and keeping the ecu memory alive. IMO the learnt data is not worth much. It’s mainly only the fuel trims and they are soon relearnt. I don’t think you would notice much difference. I swop ecu’s in and out quite often and don’t really notice anything. As for keeping the immobiliser powered on I don’t think that adds much value from a security perspective as it would activate as soon as the car was powered anyway. Regarding isolation when working on the car a small fuse may help prevent a fire but wouldn’t necessarily prevent damage from say an accidental reverse polarity mishap.

Good luck!

Bob,
I fitted such a switch on my Pembleton (they count as an immobiliser for the MSVA test) however it failed after less than 3 years (easily by-passed).
Instead I have fitted a commercial vehicle battery terminal where the cable is attached with a large wing nut - nothing to go wrong!
Hopefully Doug's professional car thief does not also carry a wing nut of the correct size!

I have an isolator switch connected to my battery terminal, but my battery is under the bonnet so easily accessible. Not needed really from a security perspective as that's what the immobiliser is for. As others have said, the ecu relearn pretty quickly, and I haven't noticed a difference when mine has been switched off. I don't have a clock to be concerned about and not fussed about retuning radio stations in, as I just press the search button and up pops radio 2 straight away.

You could install a remote controlled isolation device which also monitors the battery condition and automatically disconnects draw if the voltage is dropping as well as offering some anti-theft protection: https://www.antigravitybatteries-uk.co.uk/battery-protection/powerlock-battery-protector.html

There may be other similar things available online at less cost - I just recall seeing this one at a show a while back.

. Some of us bought a Battery Brain - it does just that and is a doddle to fit.

+1

In my 1993 T16 +4 the key is located behind the driver seat.

In the old days we simply took of the distributor cap and removed the rotor arm.