i can't afford to install an alarm/immobiliser in my car but would like to do something to safeguard my pride and joy. i was thinking of installing a switch hidden in the cabin, to something important in the engine bay..... perhaps the fuel pump or something. but i have no idea if the fuel pump is electrically or mechanically driven etc. in fact i don't even know where it is.... so has anyone got any good suggestions as to what might be my best and easiest DIY immobiliser? thanks in advance as always.

Hi there,
Your options depend greatly on whether you have a gasoline or diesel engine. If you do have a gasoline engine the switch on the fuel pump relay is a good option, as long as it's well hidden. If you have a diesel engine, the easiest place to put a switch is in the starter solenoid circuit. Here in the Washington/Ore area I feel pretty safe with my Mercedes because the keys are a little different than most rigs.
Good luck with it!

Richard Wooldridge
'82 300D/4.3L V6
Etc...

Although I have not done this myself, I have seen it done very well. A friend of mine installed a simple rocker switch inside his glovebox. The switch was inline with the ignition wire from the key switch. When he felt the car may be threatened, he flipped the switch and opened the circuit.

If I were you, I would use something like "the club" or a similar visible device. As my friend eventually found out, your car still being there is little consolation when your window, dash, and ignition switch are destroyed. Unless you have a really unique and high end car that would be stolen specifically because it is what it is (and in which case you'd also have the $$ for an alarm), a visible device is the best option. All unorganized car theft is a crime of opportunity; they'll pass you over. I heard yesterday that 1/3 of the 800 cars that were stolen in Charleston last year had the keys in them!

__________________
1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

1) One major danger in theftproffing a vehicle is causing such a frustration that the perp will do major damage in a foiled attempt.
2) If they really want your car they can flatbed it, even out of your garage. Nothing you can do to stop a determined thief.
3) The club is NOT a deterent or even a slowdown. The brake pedal tool is. Sorry, can't remember it's name.
4) Get agreed value insurance if the loss is a worry for you. It guarantees the value in case of a total loss.
5) I drive a Ferrari and believe me, I'd rather let them have their ride and perhaps have to collect insurance (4) than have it sustain even the damage of a broken window. So I leave it unlocked much of the time.
6) Just purchased a MB for my wife and was told be my insurance agent that it has signs of being broken into...a new passenger door handle and window.
7) Do you really want someone in your car with hacksaw and other ugly tools getting frustrated because the engine cranks but won't fire. Not me.

Your circumstances may be totally different than mine. Perhaps a paint job of purple and yellow polka-dots might cause them to choose a different car.

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1993 MB190e 104k

Paul:
I have to differ with you. I believe things like the club are very effective anti-theft devices, not because it will actually prevent your car from being stolen, but because it will deter the vast majority of people from trying. These items are supported by local law enforcement agencies throughout the country for this reason. I've seen the shows where people disable them in a matter of seconds, but as you said, those people will get the cars they want regardless of the device used and they are the extreme minority. Think about deadbolt locks. Have you ever locked yourself out of your house and watched a locksmith open your deadbolt with two picks in 3 seconds? You can get these picks and instructions anywhere, yet most property is protected with deadbolts. They work the same way. I agree that a club-like device would not work on your Ferrari as I said in my original post, however I believe it would be very effective in an older or more average and less desirable vehicle (to thieves!). That said, I, like you, wouldn't use one either. I never lock my jeep doors, console, glove box, etc. as people would just cut in through the back or tear stuff up trying to see why it's locked. Although no Ferrari (which model do you have anyway) the damage would be more frustrating than the loss to me, too.

In my opinion one of the best deterrents, although expensive, is a removable steering wheel. But even then...

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1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

thanks for the thoughts,

actually, i don't think anyone in their right mind would steal my car right now, it's a W123 200T ! trouble is, these days not everyone is in their right mind. the 200T is a barge, but i love it.

i am not so worried about it now as i haven't started work on it, but i fully intend to gently restore it to it's former glory and keep it as the ultimate low-cost classic utility vehicle.

my friend keeps his aston vantage unlocked for the same reason you mentioned, frustrated vandalism, but where i live, once the joyride is over it's bonfire time. so i'll take a smashed dash everytime. i'll check out your wiring suggestions and go for one of them.

in the meantime i've put in a 12v flashing diode so it looks like it's got an alarm. apparently most alarm/immobilsers are so good nowadays that thieves spend most of their time trying to steal your keys first. sometimes even putting fishing rods through letter boxes to hook them out of your hall.

long term, i guess i'll have to put an alarm in

thanks once again.

I've often thought a simple time delay fuel pump switch would be a good marketable device...
It basically lets the car get stolen, but runs out of gas half way down the block. They split and you get your car back.
Nice for car jackers too...You get out, they get in... and you watch them run out of gas as you call the cops.
Never saw one on the market, but wouldn't take much to throw one together.. could plug into pump fuse receptical for circuitry.

that is a first class idea, i'll have a think about something like that. it would be fun just making it work, let alone it's effectiveness. thanks

Basically, your options are switching the:
1) Starter
2) Ignition
3) Fuel pump

If you are really paranoid, you can do all 3...

As an aside: I once saw a device that was basically a one-way check valve on the braking system that you could enable. Once hydraulic pressure built up, it would not release, so the braking system would essentially anchor the car in place.
I would have to wonder where your car would be abandoned with these types of 'latent' devices, however...

Best of luck.

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1986 300E 5-Speed 240k mi.