Back over in the C5 General forum there's a thread going about disabling the car so that scumbags can't get the car started.

A few ideas have surfaced like hidden switches, headlamp flashers and cigarette lighters (all needing to be operated before car will start).

Seeing as this is the Electronics forum, let's get down to specifics.

Anyone got any good creative imobilizer ideas?

A simple idea seems to be some form of switch to break the starter solenoid circuit. Then all other circuits would be operable but the starter won't crank.

Would it be best just to use a switch in series with the starter solenoid? How about using a switch to energize a "normally open" auxillary solenoid that would make the circuit to the starter solenoid?

**Yes I'm aware any imobilzer can be overcome and a flatbed could be used to steal a Vette that doesn't even have an engine, so let's leave this out of the conversation.

 

Related, but a little different, is what I did with my old convertible and the alarm system I put in it.

One thing car thieves will do if they are flatbedding a vehicle is to reach underneath or pry the hood and cut the battery line to kill all power.

So what I did is added a small 4 amp/hour battery as backup to run the alarm. It was charged by the vehicle, but was isolated in the reverse. I had the contacts of a normally energized relay as one of the alarm inputs. The other was on the interior lights because they came on as soon as you pulled the door handle. So, the relay is normally energized by the vehicle battery/system and if the main battery was disconnected/cut, the relay would open and trigger the alarm which ran off the smaller hidden battery.

And bingo, you instantly know if someone is jacking your car or as an added bonus if your battery dies while parked (because there's no more voltage to hold the relay energized). Keep in mind though, with this option, the horn & lights won't go off, only the alarm siren, of which I had two hooked up, one inside and one under the hood.

 

Actually if your worried about a flat bed you can turn your frnot wheels as hard as they can go to the left or right. Which would help prevent it being towed from the rear. Put your Ebrake on as well. Buy a steering wheel lock so it cant be moved. Lock nuts on the wheels. Viper alarm system with a visable led light. Theres no way to absoloutly prevent it though but these would make it more difficult. I'd be more worried about vandalism than it being stolen. Goodluck on your security.

 

Vandalism is why I had the door handles rigged (armed with button 1 press). I also had a proximity sensor for the interior for when the top was down (armed with button 2 press).

It never helped though - they slashed the roof*, reached in, unlocked it, and the alarm went off when they tried to open the door.





* not my vette, my old car

 

But back to the original question, I would think something that cut off the fuel line/pump would be the most effective. A switch or relay or something, but I would think nothing easily accessible.

 

You can do a lot to a C5 to make it not work. Ask anyone that has had a problem with the Column Lock Bypass.

I see no reason why you couldn't tap into that circuit and open it. The computer will allow the engine to start, but you try and move it and the engine dies.

You might also look into removing the hood release and installing a big solenoid to keep people from popping your hood without the remote. Better have a way to open it in the event of a dead battery, though. (Maybe a separate power feed to the alarm in a hidden location?)

Mark

 

The easiest thing to do is to tap into the starter disable. The relay ground wire is easy to get to and all you have to do is run a toggle in line with the ground. This will not let the car start, even with the key. Starter wire is purple relay is in passenger footwell, just trace to find the ground.

 

how about rfid? or electronic combonation lock triggered by a sequence.. maybe a double click of the key fob unlock then flicking your highbeams?

 

Wouldn't that relay's coil serve to drain the main battery much faster than otherwise? I'm sure it would be fine for a day or three, but even a small relay's coil current will eventually drain a car battery.

 

One of the first mods I made to my C5 was a hidden kill switch. I had a 6-speed, so I simply cut the wire that tells the computer that the clutch is depressed and installed a toggle switch. Auto tranny cars can do the same thing with the 'park position' wire. Even if you hand someone the keys, they'll never get the car started without flipping the switch. Check out this pic to see where I put the switch under the dash.

As a temporary solution for long term parking (airports, etc...) you can just pull the fuel pump fuse.

 

Actually, I got a week easy. And since it was my only vehicle and driven almost every day, it was never a problem.