Ideas for hidden kill switch?

[DriverX]

As I pour more blood, sweat, time, and money into the XJ, I been pondering the thought of a hidden disabling switch as a security measure.
Anyone done this effectively and easily? I'm pretty good with simple electrical projects, but I'm not all that familier with the OEM harness.

Any hints or advice appreciated.

thanks,
-mike

[railroadjeep]

I was thinking of doing just such a mod myself. I haven't looked into the harness yet, but my thought is there has to be o power supply wire to the ignition switch. Thus, if I put a toggle in that wire I would therby disable the ignition. Course my XJ is 10 years older then yours so I'd think there's going to be a bit of diffrence in our wiring! my other though is to put a kill switch for the fuel pump, since I know that wiring quite well. Yes, they will get it started perhaps, but they won't make it far!
Now as for where to put the switch? Under the drivers seat, or passanger's, bury it in amongnst my lighting control toggles, glovebox, center console? Mainly I think of a place not easy to bump it by accident and one that's hidden.
Just my .02 worth.

Chris O.

[XJJPR]

Funny you ask, I was cutting my latest project up a few weeks ago and found a cool place for a kill switch. In the back panel behind where the spare tire was is a ground wire attached to the inner fender support. That ground wire is for the rear half of the elect. system and also controlls the fuel pump. If a switch was installed on that ground wire and hidden in the back (or moved up front) it would make for a nice kill switch. No pump = no run.

mark
orgs mfg

[Beezil]

excellent info hinkley!

you'd better keep an eye on your keys in moab my man.......

[XJJPR]

Will we even need a key for your rig?

hinkley

[rockwerks]

Will we even need a key for your rig?

JUST A GOOD SWIFT KICK:D

[Eagle]

The neatest place for a kill switch I've heard of was a pushbutton switch that was mounted inside the cigar lighter receptacle. Know off the actual heater element and hollow out the lighter shell, and then plug the knob back in the hole.

[xjjunkie]

check this kill switch idea out.

The World's Best DIY Immobiliser

Build your own car immobiliser that is simple, cheap and very, very effective.


By Adrian Cuesta


If wiring up a couple of relays doesn't worry you and you can handle a soldering iron and a multimeter, this immobiliser is for you.

You only need a:


12 volt heavy duty car relay;


12 volt Double Pole Double Throw (DPDT) relay;


12 volt flashing LED;


reed switch that closes when a magnet is nearby;


pushbutton that opens when pushed;


broken remote from a car alarm;


and a magnet.

Most of these bits and pieces you can get from an electronics shop.

Like all immobilisers, this one shuts down the car's EFI or ignition system. But what's different about ours is that if the thief steals your keys (with the remote control attached), he still can't drive away with your car. That makes it just about unique!

So how does it work?

The guts of the remote transmitter case are removed and the magnet is placed inside. The circular magnet from a tiny speaker has been used here. When you enter the car, you casually swipe the transmitter case past a special place within the car's cabin. This place might be on the centre console, a part of the dashboard - pretty well anywhere. Hidden behind the area that you swipe is the reed switch - a switch that is sensitive to magnetic fields. The swiping triggers the reed switch that in turn switches off the immobiliser.

Because the reed switch is located behind the plastic of the dash or centre console, there's nothing to see. The swiping movement can be quite natural - part of your hand movement as you put on your seatbelt or settle yourself in the seat. That means that even if a potential thief is watching you closely, he doesn't get any clues.The remote (at right) triggers the reed switch (left) whenever it comes close. Only you know the location of the reed switch!

When you want to arm the immobiliser, you press the button. The pushbutton can be in complete view - the thief gains nothing by ripping it out and either disconnecting the wires or bridging them. When you press the button, the on-dash LED starts to flash, indicating the car is now immobilised. It also reminds you to switch off the system when you re-enter the car.

The Circuit

The diagram shows the circuit that is used.When this DPDT relay is not pulled-in (ie has no voltage applied to the coil), it connects the LED to 12 volts, causing it to flash. At the same time it also stops power flow to the heavy-duty automotive relay, in turn disabling a vital car starting circuit. The car won't start - the immobiliser is activated. Disconnecting the car battery switches off the flashing LED but makes no difference to the position of the DPDT relay. (Note that the LED is polarised and so must be connected the right way.)


You want to go somewhere, so you swipe past the open reed switch with your transmitter case. This momentarily closes the reed switch, allowing power to flow through the DPDT relay's coil. It pulls in, with the second coil power supply path through the top contact causing it to latch - that is, stay pulled in, even after the reed switch has opened. The bottom contact of the DPDT relay then feeds power to the heavy-duty relay, causing it to pull in and complete the car starting circuit.


You drive to your chosen location and want to disable the car. A single push of the normally closed pushbutton breaks the latching circuit of the DPDT relay, causing the relay to open. In turn, this stops the power feed to the automotive relay, and so it also opens, disabling the car. The LED starts to flash showing the immobiliser is set.

Installation
The system can be installed in three separate parts: the DPDT relay, the heavy duty automotive relay, and the reed and pushbutton switches. We mounted the DPDT relay in a 35mm film canister. The relay that we used fitted neatly into the canister, with the wiring passing through a hole drilled in the cap. The canister was mounted under the dash within the wiring loom.

The heavy-duty 12 volt relay should be mounted close to where you break the vital starting circuit. A number of different approaches can be used. In an older car, inserting the relay in the low tension ignition coil power feed will prevent the car starting, as will open-circuiting the ignition key starting signal to the starter motor solenoid. However, if you do the latter, the car can still be "jump started" - not what's wanted!. If there are high current fusible links used for different circuits, it's easy to keep pulling the links until the car is as dead as a doornail and then wire the relay to open this circuit.

Finally, if your car has an electric fuel pump, the immobiliser can disable this. However, note that both EFI and carby cars will still start and run for a short period even with the fuel pump stopped. This might be just enough time for the thief to drive to the middle of the nearest major road intersection before the car dies!

The 'arming' pushbutton can be mounted anywhere on the dash. Note that if this button is accidentally pressed while you are driving along, the engine will immediately stop. Thus you should mount it where accidental activation is impossible.

The location of the reed switch is very important. It should not be awkward to access when you are seated and should also not be so close to the ignition switch that the immobiliser is disabled by the thief without him realising it! Its location is best picked when you are seated in the car. Attach the reed switch to the inside of the plastic panel using a smear of Liquid Nails or similar adhesive.

The most complex part of the system is the wiring of the DPDT relay. We built the complete system on the bench so that we could easily check that everything worked. With the system mocked up, the flashing LED should work as soon as power is connected. Swiping the hand control past the reed switch should switch off the LED, causing the DPDT and heavy-duty relays to click. Pressing the button should cause the relays to again click and the LED to start flashing.

Once the system is operating on the bench, you can install it in the car


http://www.imagestation.com/picture/sraid76/pd232a84576cf206cecb14173cbb903bc/fb421f91.jpg

[vintagespeed]

That's a kickass idea. I've wired in relays into the main ignition harness many times on other peeps rides and ran to a remote location, but using a reed switch would be much nicer. Good info!

[Yucca-Man]

I wired a switch into the dash on my 87 Toy 4x4 years ago to kill the alarm. I didn't have a/c, but there is a button on the dash close to the keys; I could bump the button stealthily before starting the engine. I've looked for similar places on the XJ and the cig lighter sounds like a great place!

[ChuckD]

Like mark said, kill the fuel pump, or put a kill switch off the CPS. That sure would drive any theif crazy. :D

[Walt Stanley]

In my '98, I put a toggle switch next to the left side of the glove compartment box. If I open the door and look down the side for a spot that is hard to see and that's where I put the switch. I spliced into the wire from the park/neutral position switch and the engine starter motor relay. Open the glove compartment door, flip the switch and it's no start.

[upmudrat]

How about one of the old floor mounted headlight dimmer switches? Just mount it up higher than normal. Wire it to break the circut for the starter or fuel pump.

[xjblue]

I've done the fuel pump cutoff, it won't start if its been sitting for a while but you can get about 5 to 10 yards if there is still some fuel pressure built up.

I like that reed switch idea! stealth is the key to this issue followed by ease of engagement and habit formation. Anything out of the ordinary will be a giveaway, anything that looks normal on the dash can still be easily tested. I've asked family and friends to look for my switch to test how hidden it is, they would click all the gadgets on the dash after looking quickly in the nooks and crannies, for those who found the switch it took them a good while.

One Idea I heard for a good circut to disable is the neutral safety switch. If it can be done, I believe any unusual wiring would be easily hidden.

Theres always rigging your fuel tank to explode ala the road warrior!

[Speed_racer]

In mine, ive got all the plans, and will do it soon of a 3 switch setup, wired to need a "code" of up/down settings to get it...

Along with a FAKE ONE wired under the steering wheel, and the other 3 in the glove box :D

[CheapXJ]

how about something stupid/simple like having to turn on a map light to allow it to start or something to that effect

[TOZOVR]

I have a kill switch on my '99...it's a hidden switch that merely cuts the power to the Starter Relay...this way I can just use a switch as there's little power being used AND, if the switch is in the off mode, you can't even hotwire the truck.

cost about $4 in parts and wire :)

[Colin W.]

I've been thinking about this for a while, and couldn't you wire up the window lock switch to activate the starter relay when it's in the locked position? Maybe it's been done a lot, but I've never heard of it. I certainly wouldn't look there if I were a thief.

[giranger]

I've got one on my 96 with overhead console. What I did was wire a switch inside the sunglass holder. When I close the "door" it shuts off power to the starter by itself. All I have to do to turn on the XJ is get my sunglasses out and "bump" the switch at the same time. Works great and no way to see it.

[2offroad]

not a kill switch, but do like Woody and have spiders weave webs in the holes where the windows were and when the thief trys to steal your XJ the spiders grab them and wrap them up for the cops or eat them.

[woody]

Had one try to kill me the other morning on the way to work.
It lept across in front of me, and spun a ray of it's damn web into my eye (the good eye) and we went a few rounds... A jolly old 50 mph backroad slapfest while trying to see and juggle a hot cuppa joe.

My junk doesn't lock, so I keep the interior pretty well unappealing to a thief... If I was really motivated to have it not start, I'd pull the coil wire and/or fuel pump relay. If I was mean I'd leave large venemous snakes loose in there.

JMHO, but if someone has time and access, they'll find a hidden switch.

[forgiven]

Some of you guys think WAY too much. I was gonna hide a switch wired to my ballast resistor for the fuel pump, duh.

[Amund2]

I've thought of this as well. The first a hotwiring thief is looking is under the dash. With a little lack of luck the thief will hotwire the car BEFORE your hidden switches and circuits... I've thought of cutting the line and installing a switch to the fuel pump under the car, maybe having a switch sticking up under or behind the driver's seat, the wire runs about under there if I remember correctly.

[WILDHORSE]

On a buddy of mines 85 Mustang we just cut into the fuel pump wiring and ran it to the unused fog light switch. No lights, no fuel, no run.

WILDHORSE

[Sarge]

Something else to think about. If a thief breaks in and tries to steal the XJ but it wont start and he flees, all the insurance company will usually pay is for vandalism. Which aint much usually. But if the thief gets the vehicle to start and move any amount before it shuts down then it is attempted theft and the insurance company pays more. Also the cops can hit him with theft charges. I think a company (Joacobs Electronics) makes just such a system.

Sarge

[TOZOVR]

Originally posted by Amund2
I've thought of this as well. The first a hotwiring thief is looking is under the dash. With a little lack of luck the thief will hotwire the car BEFORE your hidden switches and circuits... I've thought of cutting the line and installing a switch to the fuel pump under the car, maybe having a switch sticking up under or behind the driver's seat, the wire runs about under there if I remember correctly.

Not if none of the wiring is under the dash. mine comes in and is routed to the rear of the truck...play all you want under the dash, the starter relay has no power, and thus no starty.

[DriverX]

Thanks for all the input

I 'm thinking along the same lines as TOZOVR. I'd rather the rig be immobilized.
I haven't really looked into it yet but I'm going to interupt power to the starter relay somewhere hard to detect. The fun part will be hiding a really small switch. I'd say where, but that would defeat the purpose;) .

-mike

[johnnyc]

Originally posted by Eagle
The neatest place for a kill switch I've heard of was a pushbutton switch that was mounted inside the cigar lighter receptacle. Know off the actual heater element and hollow out the lighter shell, and then plug the knob back in the hole.
My buddy wired up the brake pedal interlock to the cigarette lighter. In order to shift out of park, the lighter has to be pushed in. For added security, you could remove the lighter and take it with you. Sure, a thief could bypass it, but it would take a while to figure it out.

[eMEDIA Designs]

I've got one on my 96 with overhead console. What I did was wire a switch inside the sunglass holder. When I close the "door" it shuts off power to the starter by itself. All I have to do to turn on the XJ is get my sunglasses out and "bump" the switch at the same time. Works great and no way to see it.

Ya but if ther jackin your ride why would they not jack you shades first and steel you rig looking cool????

something to think about

[ren]

My fuel pump relay is wired to the seat belt warning harness. no belt, no drive. How many thieves actually use the seatbelt BEFORE they try and start the truck, hmm?

[Menzenski]

Ya but if ther jackin your ride why would they not jack you shades first and steel you rig looking cool????

something to think about
Props for searching, but you're a little late.