Yeah, I know...
I've had my car for 4 years and have never had keyless entry.
The best thing for the rest of you to do is to buy an OEM transmitter and have the dealer code the car, but I've put it off for 4 years because it wasn't worth the $300-$400 that the whole repair would cost. That, and you all know how I love to tinker, so...
I bought this unit off of eBay for $12. It is simply a series of relays that are controlled by the transmitter/receiver.
Set Kit Universal Car Remote Central Entry Lock Locking Safety | eBay
Below is the wiring diagram for the door lock mechanism. As noted in the photo, when you turn the key in the door lock, you are simply grounding either the lock or unlock wire, telling the immobilizer to arm/disarm.
Brown = ground.
Brown with White stripe = lock.
Brown with Red stripe = unlock.
What we want to do is tap into the lock and unlock wires so that we can remotely ground them, locking or unlocking the car. Tracing the wires back, they are easily accessible from the entry point right above the fuse box (remove fuse box cover by removing the 4 Philips screws).
The 3rd party unit uses remotely controlled relays to perform this same function (the cars system is safe since the 3rd party receiver is isolated and the relays just act like switches - same as the door lock).
This picture is a mess, but shows how simple the unit is. Basically, I just fed ground to both relays (by shorting them to ground) and when they are activated by the receiver, they switch the ground to the either of the 2 outputs.
The unit also has outputs for a flashing light to indicate when the car is successfully locked or unlocked (side marker lights?). I have not hooked these up yet, but fuses A3 and A4 (for the side markers) are right there, so will soon.
Lastly, it has relay outputs for a trunk actuator (both + and - ...I think ours is negative actuated, just like the door lock microswitches).
So, that's it!
4 wires; lock signal, unlock signal, 12V+ and ground (will add the trunk actuator and side marker flash later).
After finding the right wires, it took 20 minutes to install and now I have remote arming capability. Works just like OEM
Like I said, the best route is to go OEM, but I have time and am bored. This works great, though. Have not tested range, but works from at least 25 feet away so far. Also, the shape of the fob is just right to fit a crest on, so it will replace my leather keychain soon.
You guys can field the new guys that don't get my insanity
Video...
https://www.youtube.com/watch?v=Ghsv5X1UW4U&feature=youtu.be