Electronics - a primitive immobilizer?!

Hi everyone.

I'm new to this community and I already have a question for you.

First, regarding my car:
Volkswagen Golf 3 TDI, year 1994, 1Z engine.

Now that I've invested a lot of money and time in this car, it would be a shame if...
If someone were to steal it.
At the same time, I don't want to spend a lot of money on an alarm system or immobilizer.

So, I was thinking about whether it would be possible to simply create an electrical interruption (using a switch ) in a circuit that effectively prevents the car from starting, and then solder it in?
Of course, the switch will be well hidden.

Since I unfortunately wasn't able to participate in the development of the golf , for whatever reason , I have no idea where I should interrupt this circuit.

A wiring diagram for the ignition system would be great, but even with that, I would need to know where to find this cable in the car itself.

I am grateful for any answer.

PS: In your opinion, is this an effective anti-theft measure?
So, an alarm system in my area here only causes noise disturbances .

Hello,

What kind of neighborhood do you live in, that someone would steal a 1994 Golf?

Sincerely,
Christian.

Mirsad wrote:

So, I was thinking about whether it would be possible to simply solder a simple electrical interruption (using a switch ) onto a circuit that effectively prevents the car from starting?

"Take a look at 'Relais 109'. That device does exactly what you want." A simple WFS (Web Feature Service) can be implemented here with a targeted intervention and without much effort.

First of all, thank you for the quick responses. Relay 109 sounds good, and I think I even know where it is . I'll start looking for it right away.

@chris:

Why would someone steal a 1994 Volkswagen Golf?
Why was my basement cleared out, and almost everything in it seems useless?
Why is my 10-year-old bicycle missing?
Who is putting in the effort?
A beginner thief practicing their internship at Mafia GmbH? Hmm?
I have no idea, I just know that literally everything is being stolen, why not my Golf, which any 10-year-old could break into?

Do you not have partial casco insurance? "They pay out in cases of theft..."

Thieves apparently have the unpleasant habit of vandalizing cars when a theft attempt fails. As long as nothing is stolen, the comprehensive insurance will not pay out.

Before I let someone completely destroy my car and see no money for it, I'd rather have it stolen and hope that it's eventually found in somewhat decent condition, because the (mostly young) thieves will probably get bored and lose interest.

Just a suggestion...

Then I'd rather have an Aral gas station with a noise-making feature; maybe that would scare off thieves (possibly), unless the car is parked deep in the wilderness behind Wallachia.

I'm also considering getting an alarm system installed. I already have a standard immobilizer, but I don't have partial comprehensive insurance (who's going to pay for that????). For that price, in two years I'll be able to get a 'new' used G3.


But if such a hidden switch is to be installed, perhaps connecting it directly to the battery cable would be a good idea.


Otherwise, regarding the 8-pin connector on the fuel injection pump, the most important cable needs to be cut somewhere, then a relay is connected, and this relay is then activated by a switch. (This relay could also be activated wirelessly if you have retrofitted the keyless entry system in your G3, like I did ).

I would, like Bertil, also connect it to the 109 and place the switch in the control line leading to the engine control unit: that's where it will have to handle the least amount of current, and it will be located inside the car, where the switch is presumably going to be mounted.

If your 109 model still has the "normal" wiring configuration due to its production year (meaning it has 4 connections instead of a common 12V supply for the coil and load current), and both inputs are powered with a constant positive voltage (terminal 30), I would recommend using a self-holding circuit.

Connect the switch to the 12V power supply of the relay coil, and connect a short piece of wire from the load output of the 109 to its connection point, where the switch is now located.

Then, with the engine running, you can open the switch without the engine turning off – this provides an added safety feature in case, for example, there's a malfunction in the switch or accidental activation.

If the 12V for the winding of the 109 are supplied from the ignition system (terminal 15), a diode (1N400x or similar) must be placed either before or after the switch, with the diode oriented in the correct direction for current flow.
Otherwise, with the switch closed, the motor would no longer be able to be turned off because terminal 15 would be powered "backwards" from the output of the 109 device.

Implementing a self-holding function with a 3-pole 109 switch would unfortunately be somewhat more complicated, for example, using a switching transistor, a base resistor, possibly a diode in the base circuit, and a flyback diode on the relay to protect the transistor, etc.

Quote:

But if such a hidden switch is to be installed, perhaps the battery cable itself would be a good idea?

You can already tell by looking at the cross-sections near the battery that a significant amount of current is flowing. Consequently, a switch that would be suitable for such a high current draw would also have to be robust and expensive, otherwise it would likely burn out immediately.

The battery disconnect switch isn't a problem, it's just that you don't easily find it .

I personally prefer the 180dB horns inside the vehicle, or even better, two tear gas cartridges inside the interior (for a second attempt). However, you can't get that stuff out of the upholstery .

Sure, here is the translation of the text from German to English:

'Cu Gremlin'

You could also install a device that uses a triggering gas... but if that thing accidentally goes off on you...

Well, I'm all done now.

and a VW engineer suggested that I simply cut the blue/black cable with the number 15, not the thick red one, which is connected to the ignition.

This blue/black cable actually goes to the fuse box, and it already has a connector attached from the factory, which is just bridged over.

I assume that the original VW immobilizer is supposed to be plugged in here, but I don't have it .

Okay, I did the same thing, but in a different location where the thief would first need to remove disguises for 2 hours (I took 3 hours myself, but I assume the thief is more skilled ).

I won't tell you where the switch is.

If the 12V for the winding of the 109 are supplied from the ignition system (terminal 15), a diode (1N400x or similar) must be installed in the forward direction, either before or after the switch.
Otherwise, with the switch closed, the motor would no longer be able to be turned off because terminal 15 would be powered 'backwards' from the output of the 109 device.



I hadn't thought of that, but does it work without a diode?

I switch the switch, and I can drive, and then turn it off again.

With the switch open, the indicator lights do not work, and the engine cannot be started (it then sounds as if the battery is dead ).

It's definitely terminal 15 that's coming from the ignition system.

Mirsad wrote:

I switch the switch, and I can drive, and then I can turn it off again

.
...and the engine keeps running?? Or does it turn off when the switch is opened?

Quote:

With the switch open, the indicator lights do not work, and the engine cannot be started (it then sounds as if the battery is dead )

.
Then the switch is likely located before the split where terminal 15 connects to the EDC (Electronic Diesel Control) and the instrument cluster.
If a not-entirely-stupid thief sees that the indicator lights on an organ remain dark, they know that a hidden switch is likely involved.
Many people know where they need to look, and they will find it faster than you might like.

If the lights are on when playing the organ, then he must be quite clever to distinguish between a hidden switch (-> it might be worth investigating) and starting problems (-> investigation is futile).
Therefore, I would place the switch – if it must be in wire 15 – in a location where only the "ignition on" signal is transmitted to the engine control unit.

Hey guys,

How about we keep the system running, but only in emergency mode? Simply connect the switch to a wire that is used for controlling the turbocharger pressure or something similar.
If the car doesn't run properly, he won't enjoy it and he'll leave it (or, ideally, it will even come to the attention of the police).
How about having the hazard lights blink continuously until the switch is turned off again?
There are probably many things that can make a vehicle unappealing.

I've also considered using a spark coil to apply a pulsating voltage to the vehicle when the alarm system is triggered. This could be achieved by simply connecting the spark coil in parallel with or instead of the alarm system's horn, and grounding the high-voltage output of the coil via an insulated static discharge rod mounted underneath the car. Then the person who caused the damage will at least get a proper beating if they touch the car...

Greetings.

Eike.

Well, the most effective anti-theft device was still the one from James Bond's Lotus .

CU Gremlin.

Well, the most effective system was still the immobilizer from James Bond's Lotus .

CU Gremlin

What would that be? I don't quite remember the movie.

... and the engine keeps running?? Or does it turn off when the switch is opened?

The engine is stalling .

Well, if I ever feel like soldering again, I'll try the other version with the self-holding mechanism, since my relay is a 'standard' one with 4 pins.

Currently, I'll leave it like this; it should be sufficient for a 1994 Golf 3 TDI.

Thank you for the tip!

PS: What do you think about it? http://www.kfz-diebstahlsicherung.de/autotypen.html
'However, it's too expensive for my car (around 370 euros without installation), but if I had a really valuable car, I would definitely buy it.'