Kill switch brainstorm

[gstuartw]

I'm hoping to install a kill switch in my '88 B2, something that is discrete and not where a thief would typically look.

The first decision is kill the fuel or the electric?

While I like the idea of one that kills the fuel I'd rather not put a valve into my fuel line for the reason that it will be harder to put in an easy to reach place that's not in the engine compartment. (Seems like the engine compartment would be the first place to look after inside the cabin). Killing the fuel is preferable because the would-be-thief will likely assume there's a mechanical issue since it will crank but not start.

The other option is electrical.

Do I kill the power to the fuel pump and gain the same deception as a valve in the fuel line or go with something killing the ignition?

Which ever the electrical component I kill I want to be easy to access yet totally hidden. Hidden in plain sight if you will.

My first brainstorm result is to somehow convert the cigarette lighter into a kill switch. Maybe the switch is activated if the lighter is completely removed? On a 35 year old vehicle it would not be unusual for that to be missing. Even better would be to make it so if the lighter was partially pulled out? I don't care if I have to do mods to either the lighter or the socket, I have replacements if I ever want to return it to stock should I want to sell it.

Does anyone have input on this? Momentary contact switch placed in the bottom of the socket?

Thanks

Stuart

 

[Uncle Gump]

Just use the cigarette lighter to complete the switched ground to the fuel pump relay.

When the lighter element is pushed in... path to relay complete.

With lighter element pulled completely out or in its normally open position... path to relay open.

 

[Roert42]

You would have to hold the light in while you drive?


I would wire it up to kill power to the fuel pump, probably the easiest way.


I think Gump's light idea would work if you wired it the starter. That way the starter only will run when the light is pushed in, then by the time it pops out the engine is already running.


I've seen jeeps with lockable console boxes, and the switch is in there.

 

[Uncle Gump]

The lighter element would not heat up and pop out if it never had 12 volts to heat it up.

It would be just a simple on off switch. Wire the relay control circuit from the ECM to one side of the lighter... the other side back to the relay control circuit.

This does assume that the lighter assembly is mounted in plastic or isolated from ground.

 

[RonD]

In a 1988 pin 22 on the PCM(engine computer) is the Ground for the Fuel Pump Relay, 1986 thru 1994

This wire runs from PCM to the OBD1 connector in engine bay, and then to the fuel pump relay base, the green one on passenger side inner fender

If you intercept/cut this wire then fuel pump(s) will be disabled
This is probably the easiest way to disable fuel pump(s)
Its also only a 1/2 amp draw so smaller wires work fine


As for the switch
Cigar lighter doesn't have an on/off trigger, you would need to add a AMP draw sensor on it's 12v wire, which is not cheap, and then a momentary relay, also the 12v power is not shut off with key off so to reset the "trigger" you may need to rewire 12v cigar lighter to a key on wire

You could use a magnetic switch, reed switch, used for home/business door and window alarms, need "normally open" model
Not many thieves carry magnets around, lol

 

[Uncle Gump]

The lighter when pushed in... is ON

the lighter is off when it's not pushed in.

You don't need 12 volts at the lighter... we aren't using it for it's intended purpose.

Is the fuel pump relay control circuit not ground side switched?

 

[Curious Hound]

The lighter when pushed in... is ON

the lighter is off when it's not pushed in.

You don't need 12 volts at the lighter... we aren't using it for it's intended purpose.

Is the fuel pump relay control circuit not ground side switched?

I'm not crazy about this idea. It still introduces the resistance of the lighter element when pushed in. It might work. But you are heating the lighter all the time it is pushed in because it is part of the circuit and current is flowing through it. Doesn't matter which end of the circuit it's on. It's in series. It will most likely still come up to temperature and pop. Then you lose your fuel pump relay. Interesting time delay .

 

[Uncle Gump]

I'm not crazy about this idea. It still introduces the resistance of the lighter element when pushed in. It might work. But you are heating the lighter all the time it is pushed in because it is part of the circuit and current is flowing through it. Doesn't matter which end of the circuit it's on. It's in series. It will most likely still come up to temperature and pop. Then you lose your fuel pump relay. Interesting time delay .

That's what I was missing... the heater element in series. I suppose you could alter the element a bit by soldering in a bus bar.

 

[gstuartw]

I'm loving this discussion. I know nothing about automotive electronics so I'm a bit lost but I'm encouraged. Would disabling the heating element help? Though I've never really investigated it my assumption has always been that the plunger with the coil releases upon heating due to expansion of some metal component. Maybe that plunger if altered could be the bridge between two contacts at the bottom of the contact? Seems the shaft of the socket would need to be either insulated with a non conductive sleeve or trimmed to prevent conductivity where it is not wanted.

 

[alwaysFlOoReD]

If I was a thief the cigarette lighter would be the first place I would look.

 

[RonD]

If I was a thief I would pass on a 1988 BII, in 2023 it's its own "kill switch"

But kids will be kids, and that's who might attempt a theft

My own favourite kill switch is a fuel pump delay switch
Thief starts engine drives off, in 5 minutes, or whatever you want, fuel pump dies
Now the thief is out on a public road and engine won't restart, is he going to look around for a kill switch...............or get the heck out of Dodge, I am thinking the later

 

[RobbieD]

If I was a thief the cigarette lighter would be the first place I would look.

If I was a thief, the cigarette lighter would be the first thing I'd steal.

 

[ryan]

I have a 12 volt guy kit that puts a switch between vehicle power and the starter. very simple and has a keyed switch

 

[ryan]

https://www.amazon.com/Volt-Battery-Disconnect-Kill-Switch/dp/B007O0BBFM?tag=959media-20

 

[James Morse]

which is just like what race cars use... so you could mount it interior, or exterior with a jagged electric symbol next to it.
of course if they have that switch key they can turn it on...
in the old days if we were really worried we pulled the center distributor wire that'll stop it
not convenient though