cutoff switch

[Tom239]

I'd like to install a hidden switch to disable my NSX, to make it harder to steal.
Could someone recommend a point in the electrical system for this?

In the old days, it was simple to break the circuit that fed the coil's primary,
but obviously there is no single coil primary wire in an NSX. I'm looking
for a circuit which, if broken, will allow the motor to crank but not fire.
If this could be done by disabling fuel injection rather than (or in addition to)
spark, all the better. If it could be done without triggering any warning
lights on the dash that would suggest something is amiss, better still.
If it's a point inside the interior (where 'interior' includes the electronics
behind the panels behind the seats), that would make installation easier.
The NSX in question is a 1995 US market model.

 

[DocL]

Have a switch installed that cuts power to the fuel pump. :wink:

 

[Tom239]

Fuel pump would do the trick; thanks for the suggestion.

I have the service manual and see that the fuel pump
relay is indeed behind the seats. I see how to disable
the fuel pump from the circuit.

Anyone know if there would be any downside to doing that?

 

[docjohn]

I don't have an answer but(if your car is say older than 15 yrs) I would suggest replacing your main relay since you will be there mucking around back there.

 

[Cozmo]

Fuel pump would do the trick; thanks for the suggestion.

I have the service manual and see that the fuel pump
relay is indeed behind the seats. I see how to disable
the fuel pump from the circuit.

Anyone know if there would be any downside to doing that?

The only thing that sticks out in my mind is make sure the switch and wiring you install can handle the load going through it. I don't know how much the fuel pump draws but you wouldn't want to melt the wires or starve the fuel pump for power.

 

[Tom239]

The only thing that sticks out in my mind is make sure the switch and wiring you install can handle the load going through it. I don't know how much the fuel pump draws but you wouldn't want to melt the wires or starve the fuel pump for power.

I wouldn't put the switch in the circuit that carries the current that the pump draws.
I'd interrupt current to the coil of the relay (part of the main relay) that controls it.

 

[pgilliam1]

Sounds easy to me. Just put a hooded toggle inside the console - easy wire from the main relay to there, and it's all hidden. Take a picture and let us see your install - unless you're afraid we'll steal it - ?

 

[Briank]

If someone really wants your car they will come with flat bed, winch it up and be gone. Just get actual value insurance and be happy.

 

[Doc308]

Ferraris have a ground disconnect switch located under the front hood. In that arrangement, the ground wire can be separated. Different models have different switch/disconnect thingies. I like the 308 set-up--it has a plastic slide connector wihch allows for a quick and efficient disconnect. You can probably rig up a similar set-up in the NSX. The only problem might be finding a solid ground location, since our cars are mostly aluminum

 

[RJPKRP]

When I raced stock cars we were required to have a fuel pump switch in the center of our "dash" (in the likely event of a wreck the safety crew could cut the fuel flow and knew where to find it on every car on the track) as well as an inertia fuel cutoff switch on the pump.

Anyway, I agree that cutting power to the fuel pump would work for you. Kits can be found at racing supply stores.

You can also put a switch on your battery, which might be better for your particular application. Those kits are a bit cheaper and can be found at places like JCWhitney. Then just find a place to mount the switch, maybe under the front hood in an inconspicuous location or behind the drivers seat, and turn it off when you get out of the car. Works well for storing the car over the winter too!

Just my $0.02

 

[Tom239]

Thanks to everyone who has replied.

Sounds easy to me. Just put a hooded toggle inside the console - easy wire from the main relay to there, and it's all hidden. Take a picture and let us see your install - unless you're afraid we'll steal it - ?

I'll post pics of where I splice into the electrical system. The switch won't be worth taking a pic of, it's just a switch :smile:

If someone really wants your car they will come with flat bed, winch it up and be gone.

True but the cutoff switch is so easy to do and will thwart some attempts. The only car I ever had stolen was taken by driving it away.

You can also put a switch on your battery, which might be better for your particular application. Those kits are a bit cheaper and can be found at places like JCWhitney. Then just find a place to mount the switch, maybe under the front hood in an inconspicuous location or behind the drivers seat, and turn it off when you get out of the car. Works well for storing the car over the winter too!

I'd prefer not to reset the clock every time I disable the car. (Winter: I don't store it, it's a mild winter where I live.)

the answer to your question lies in the cigarette lighter, i have converted this item on corvettes, ,hot rods, cobra kit cars ,t- birds and all sorts of other cars, breaking the circuit on the fuel pump will work but it is almost expected by any car thief ,they can get around it , this system is so simple it is often overlooked, :smile::smile:

When you say cigarette lighter, you're just saying that's a simple item to use for the cutoff switch, yes? (Just making sure I'm getting your point.)

 

[NA1VTEC]

What about putting a switch in place for the ECU? No ECU, no start.

 

[Tom239]

What about putting a switch in place for the ECU? No ECU, no start.

Where on the ECU did you have in mind? It has over 100 terminals :smile:

There are so many options. It occurred to me I could disable drive-by-wire throttle, for example. Engine starts and idles, but gas pedal does nothing.

I don't want to kill power to the ECU altogether, as I don't want it reset every time I park the car somewhere. Someone please correct me if I'm wrong, but it's my understanding the ECU has a memory and re-learns after power cycling.

 

[Honcho]

Good point. You're probably better off using the fuel pump circuit. No gas no go.

 

[NA1VTEC]

Where on the ECU did you have in mind? It has over 100 terminals :smile:

There are so many options. It occurred to me I could disable drive-by-wire throttle, for example. Engine starts and idles, but gas pedal does nothing.

I don't want to kill power to the ECU altogether, as I don't want it reset every time I park the car somewhere. Someone please correct me if I'm wrong, but it's my understanding the ECU has a memory and re-learns after power cycling.

I was figuring the power wire or a switch inline to the fuse of the ECU, but you're right, the ECU would reset every time and that would suck.

 

[DocL]

People, I have a kill switch in my car that cuts power to the fuel pump and unless you are putting my car onto a flatbed, it ain't going anywhere. I've had numerous friends try to start my car and they've all given up after ten minutes of looking for the switch. Little do they know, I have multiple switches that have to be in the correct position in order for my car to start. Can it be over ridden, sure. However, it'll take time to rip apart my interior to find at least one of the switches. :wink:

 

[Honcho]

Listen to DocL. I have a similar setup in my car. :biggrin:

 

[schuey1010]

If someone really wants your car they will come with flat bed, winch it up and be gone. Just get actual value insurance and be happy.

To me all these extras dont seem like they will do the job in the long run. How many "thieves" are going to try and hotwire an NSX to steal it? It just seems like they just come and tow cars away these days.

A friend of mine had his integra stolen from his driveway. It had multiple kill switches, and it didnt have a steering wheel, or an ECU either. These scumbags just come and tow your car away and figure out everything in the comfort of their heated garage.

 

[Honcho]

The main theory of any car security system is deterrence, not defeat. Whether it is active deterrence through flashing lights and horns, or passive deterrence through hidden kill switches, the idea is to deter the thief by making it more difficult to steal the car. My police friends have often said that the best way to prevent car theft is to lock your doors. The vast majority of car thieves are like predators – they target the old and weak. In car terms, that means unlocked cars sitting in an area where they are not easily visible. Your average car thief wants to get in and out as fast as possible. He’s not going to waste time on your locked car when there are three other unlocked cars sitting next to it.

However, cars like our NSX’s are more vulnerable in the sense that they are exotic, which can act as inducement to a would-be thief to devote more effort to stealing it. Simply locking the doors won’t suffice. That means we have to devote more effort to making the theft a difficult and time-consuming process. Kill switches are a great solution here because if they are wired correctly and hidden well, it could take hours of searching, along with a electrical service manual schematic, to figure out the system. No good car thief is going to stick around for more than a few minutes. A good kill switch/alarm means that the worst you end up with is a broken window and possibly a boosted stereo.

As mentioned, if a thief REALLY wants your car, he can flat bed it out and disarm the security measures in the safety of a shop. There is really nothing you can do about this scenario, aside from possibly a GPS tracking system (but those can be jammed). However, these sorts of thefts are much rarer and more often targeted at up-market cars like Ferrari, Lambo, Bentley, etc. While there may be a “Gone in 60 Seconds” crew running out there and boosting exotic rides on flat beds, there’s probably a few cars higher on the list than my ‘91 NSX with 82,000 miles. :biggrin: Even so, if this does happen, make sure you have a Agreed Value insurance policy. That way, if the flat bed crew hits your ride, you get a big check so that you can replace it.

That being said, the vast majority of the car thefts directed at the NSX will be smash and grab joyriders, as the parts market is worthless compared to Civic/Accord/Camry and the car can’t be moved easily due to the rarity. Kill switches will stop joyriders every time. It’s worth the 10 bucks in parts from radio shack and a weekend tearing out your interior.

Just my 2 cents.

To me all these extras dont seem like they will do the job in the long run. How many "thieves" are going to try and hotwire an NSX to steal it? It just seems like they just come and tow cars away these days.

A friend of mine had his integra stolen from his driveway. It had multiple kill switches, and it didnt have a steering wheel, or an ECU either. These scumbags just come and tow your car away and figure out everything in the comfort of their heated garage.

 

[Tom239]

Alarms and kill switches and insurance all have their value, but not having your car broken into or stolen at all is nicer still. My living in a low-crime rural area works more to my advantage than a kill switch could. But I will install a switch anyway.

The "they can always flatbed your car" line, while true, does not strike me as a reason not to put a kill switch in. It's not going to take me much time, and I have all the parts lying around.