**HOW TO: Making a "Secondary Key" Anti-Theft Device.

[talonXracer]

"FROTH" over on K20A.org posted this up awhile ago and I thought it would may be helpfull over here, so with his permission I copied it here.

***ATTENTION***
This is for people with above average electrical skills only!!!

**********************************************

Froth originally posted this on Honda-Tech a while back, Reposting here to help people out :)
- - - - - - - -
Inspired by a post about a successful theft foiling by using a system like this and with the massive post about "My car was stolen" I was inspired to make a nice HOW TO complete with pictures and Radioshack shopping list :silly:

"Secondary key? Wtf is that!?" - It's basically a plug that connects to splices in your Ignition/Fuel Pump/Starter wires, Without the other side of the plug you cannot start, hotwire or even Bumpstart the vehicle. In essence, it's a ghetto ravelco.

WHAT YOU NEED: (Radioshack list/part numbers)
- 2x "2761502" - Male 15pin D-sub connector
- 1x "2671501" - Female 15pin D-sub connector (I bought two, meh)
- 2x "2761508" - Metal housing for 9/15 pin D-Sub connectors
- 1x "2781215" - 100 Feet 22 gauge solid wire, Black

Total Cost: $19.63

TOOLS:
- Soldering Iron
- Solder
- Soldering Flux Paste (This makes it SO MUCH easier)
- Wire cutter/stripper (or razorblade)
- Heatshrink tubing
- Small Flathead Screwdriver

Okay, let's dive right into this!

First things first, how all good projects should start.


Now, My workspace... :P it's ghetto but it works.


However many splices you wish to do, cut about a foot of wire for each splice. Then you can add extra wire to wire into your cars harness.


Strip that wire you just cut. Repeat for all your wires


These are my connectors, 15 pin Male/Female.


I will mount the male unit somewhere in the car, and put the female unit on my keychain. They go together quite well.


This makes your work so much easier, FLUX. Dip your wire end into the FLUX and then plug into the back of the D-sub connector.


FLUX is a solder attractant, look at that clean little solder joint!


Attatch all your other wires, do a random selection...you're going to want it random.


Now, take the female connector and bend a small piece of wire, like this.


Insert it into the female connector so it "bridges the gap" of the wires from the male connector. Solder it, Do this for all connections.


Now when your female plug is done, insert it into the metal casing, screw together and you're set. I'd put this on a Quick Disconnect on your KEYCHAIN, ensures you always have it and it's easy to connect/disconnect if you so wish.


I'd put some hot glue over the wires so they wont short out(make sure it works first) then decide what wires you want to splice where on the vehicle, LABEL THEM on the Male side of the harness then take a picture of it and put it somewhere safe(incase it happens to get messed up) now simply install it into the car, wire the splices so they cannot be detected then remove the labels for the wires and you've made a killer theft stoping device. ALL of the wires will be black so it's a pain to trace back to the source, especially if you weave it back into the stock harness :P

**BE SURE TO SPLICE ATLEAST ONE GROUND WIRE, This will make sure that a thief cannot take ALL of you wires, twist them together and start the car.**

AGAIN...
***ATTENTION***
This is for people with above average electrical skills only!!!

[VegaS10]

I can only imagine the chaos and hell this write up has caused people trying to do it themselves.

You better have a DAMN good knowledge of wiring and soldering before soing something like this.

[talonXracer]

Oh most assuredly, this is not something for beginners to try.

In fact I need to add that to the original post, thnx for reminding me.

[socal_brandon2]

Freaking awesome write up man. Maybe I'll do this the next time someone breaks my damned window :)

[james04si]

if someone wants it they will still get it. wouldnt be too difficult to trace the wires to see which pair needs to be stripped and twisted together to make the contact. I personally woundnt hack into my factory harness just do do this and I do have the skills to do the soldering nessecary.

[talonXracer]

if someone wants it they will still get it. wouldnt be too difficult to trace the wires to see which pair needs to be stripped and twisted together to make the contact. I personally woundnt hack into my factory harness just do do this and I do have the skills to do the soldering nessecary.

This will defeat most any thief if he doesnt have a tow truck. You can do this with a OEM Honda connector and use Honda wire and unless they have hours to trace wires they wouldnt find it. I would use this as a last ditch anti theft tool, like when you have to park in a not so safe location for a bit. You dont have to put the connector/key in a obvious location. Embedded in the harness it wouldnt be found.

This would also thwart the thieves that have the Honda immobilizor algorythm, the same as removing the E-brake switch will.