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MG TD TF 1500 - Security device

While waiting for the exhaust manifold to arrive, I've been working at other tasks; repainting the starter motor and putting the throttle spring bracket back in its rightful place (on a starter motor bolt, instead of a bolt on the exhaust manifold); wired in my 12v accessory sockets on the dash... last pointless product was wiring in my M-lock device.
To back up a little, years ago, I acquired a security device called an "M-lock" from a company called motogadget ( for a motorcycle I used to have (They kindly gave me the device free as a "sponsor" of my border-to-border biodiesel motorcycle ride, but that's a different story).
The mlock is an RFID device and it can be hidden anywhere, and it will control/disable anything you want (but it requires 12v negative earth, and RF suppression on your plugs).
It has a keyfob which if you wave it in front of the device, the RFID chip is read and the device activates. It's very simple, completely solid state, and unlike any key device, cannot be "picked"... you have to have the right key fob, or it will never work, period.
As I live in Tucson, AZ, the car theft capital of the US, I'd always wanted to add whatever deterrent I can to keep the car from being driven out of my carport.
In previous projects converted the car to negative earth, and while replacing the ignition wiring and plugs, I installed RF suppressing plugs, so that the car was now ready for the M-lock.
I have installed the device just under the dash. I've wired in an LED light which lights up when the m-lock is activated, so I know its working. And by installing the m-lock in series with a 40 amp relay, I've set it to control the entire vehicle electrical system.
In short, you can have the key to the car, but nothing will work unless you wave the special fob in front of the mlock, and no thief on earth is going to figure out this, period.
Of course, they can just winch the car up onto the flatbed truck, after cutting through the chain I've used to tie it to a massive rod passing through a brick wall; but you cannot stop a truly determined and expert car thief.
A friend had her 60's VW driven off from a parking lot while she was grocery shopping, and they found the car minus most of the parts three weeks later; the thieves had probably made a few thousand on ebay.
Anyone trying to do that with my car is going to assume that the car is just dead, or have to open the bonnet and start rewiring.
So now when I get in the car, I hold the fob in front of the hidden device, and the LED lamp lights up (it's on a panel between my turn signal switch and heater switch). Only then when I put the key in the lock will anything electrical work.
I know that many feel that our cars just can't be made secure, and that is perfectly true. But I feel good knowing that this will at least slow your weekend joyrider thief down for just a few minutes...

Geoffrey M Baker

Here's a brief demo:
Geoffrey M Baker

Surely if you can get to the coil terminals and the battery a single piece of wire will hot wire the engine. Removing the rotor arm will be better unless the robber has a spare in their pocket. One trick I read about some time ago is to put number stickers on the HT leads but not in the correct order. When you leave the car connect the wrong, but apparently correctly numbered, leads to the plugs. Unless the thief knows the firing order and can find TDC they will not be able to start the engine. I suspect the major risk though is having the car trailered away and the only way I can see protection for this is to fit one of the vibration sensor alarms which maplin sell.

Jan T

J Targosz

This device cost me nothing because I already had the equipment from a previous project.
My next step is slightly more ambitious: to use a "tartopper" battery cover, a Miata battery and a 150A/300A switch with the mlock, so that I can build a fake battery, and hide the real battery AND remote controlled switch inside. The thief will be unable to do anything even with full access to the coil and the wiring and the battery... without disassembling the fake battery... or bringing their own.
Geoffrey M Baker

I've always felt that if you're worried about theft (which isn't really a problem with these cars) then the best thing is a fuel pump cutoff. That way, the car will appear to start and run properly, but will stop running shortly thereafter. The thief will then assume it's broken down and more than likely will not want to raise the hood to troubleshoot it on the curb of a public street.
Steve S

Steve, quite true. Of course, my car cuts off the pump as well of the rest of the electrics; and they can't fix that by simply sitting in the car and rewiring the ignition switch. Won't work. They have to open the bonnet and run some wires to bypass the mlock and relay ... perhaps not much of a deterrent, but maybe enough to stop the guy thinking about stealing it when I've left it parked outside Target and will be back in five minutes... and that's all I'm looking to do. As I say, at home I keep her chained up (also not much of a deterrent)... but it does make me feel more secure. You say theft isn't much of a problem with these cars, which is true - I'm sure our Honda civic is much more targeted for theft - but as I said earlier, I know someone who had their 60's VW stolen (to be sold for parts)... in the twenty minutes that they were shopping in a grocery store. I'm hoping this is enough to deter that kind of possible thief, no more!
Geoffrey M Baker

It's certainly a deterrent that no thief would expect on a TD! For that reason alone, it's a really good one. They would probably spend more time trying to find the kill switch than it would take for you to finish your errand.

The only thieves that I ever worry about are joyriders. I doubt anyone would steal a T-Series MG to sell as parts. The community is too small and tightly knit for that.
Steve S

This thread was discussed between 17/05/2014 and 18/05/2014

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