So yeah. I finally finally finished the keyless entry mod for my car. I had been meaning to do it for quite sometime. I haven't done any mods in a while so I was hesitant. My arm was pretty badly disabled in an incident that landed me in the hospital for a month. I had to go through several MRI scans, which some people claim will fry your chip. Check my previous post for proof that this isn't the case. My tag was an EM4102 12mm x 2mm that I got from Trossen Robotics (see previous posts for info on my implant).
0.5-Amp SPST Reed Relay at 12VDC - Radioshack Model: 275-233 - $3.99 (got 2)
Rectifier Diodes (25-Pack) - Radioshack Model: 276-1653 - $3.49
Dual Mini Board with 213 Holes - Radioshack Model: 276-148 - $2.49
Black and Red medium gauge wire - don't know the gauge or cost but got it at Radioshack
Extra remote access keyfob for the car - Prices vary where you go to get them. I had an extra
RadioShack® Lead-Free Solder (SnCu) 0.032" - Radioshack Model: SnCu 0.032 - $7.99
xEM Access Controller from Dangerous Things - Buy at Dangerousthings.com - $15.00 (friend discount!)
Wiring nuts from Ace Hardware - $3.99
Total cost: 40.94 + Taxes. Depending on your setup, you might pay more or less.
Next up i need to put the reed relay, diodes, and some wires together to tap into the keyfob for my car. I chose a mini project boards since the size seemed right. Made some clever bead lines and soldered wires to them.This is the pinout for the reed relay.
I took a project board and lined up the pins for the relay and then soldered them in place. I then ran some beads to various parts of the board to accommodate wires for the RFID reader and the coil pins that go to the keyless remote.
I needed to make sure I threw a protection diode in there somewhere to take the backlash of the current that was generated when the relay closed. So I decided to wire it in line with one of the lines from the coil to the keyfob. This was the only picture I was able to grab since i was busy testing and soldering. So I put one a diode in line to the keyfob from one of the coil pins... KEEP IN MIND. This was a test. The banded end of the diode actually has to go the other away around, facing the line to the remote. Do not wire this with the banded end pointed to the coil pin or it will block all current coming from that way!
Now, on to the keyfob itself. It looks like this:
After ripping it apart, i identified the two bottom pins of the unlock button to be the ones that the coil lines needed to be soldered to. Here are a few pictures of what i ended up doing to modify the case, rubber protective covering, and the board itself.
|The picture above shows the area i started to take off of the remote. I went all the way across and just cut the entire bottom out in case i needed to snake other wires in there later.|
|The photo below shows the cuts I had to make to allow the wires to travel through without any hindrance. The button I cut out is for the trunk release.|
Proving a good fit. I used hot glue to hold my wires in place.
Onward to actually installing this thing! We removed the lower dash panel to get at the area under the steering column because it had a lot of open space. The next pic is a little wibbly wobbly, but we were too busy trying to get the thing zip tied down to something that would keep it in place. We ended using the frame for the hood release. It was in a perfect position. To power the reader, I tapped the +12v line and ground line from the battery to my stereo to give it constant power. Get a +12v line wherever you find it easiest.
|All snug in its new home zip tied down.|
|The wiring for the antenna. This photo is just left of the one above it. The next picture will show how we ran the wires up to the windshield|
|Running the wire for the antenna up to the windshield. We spliced in an extra foot and a half or so of cord I stole from an old AC adapter (Ghetto!) It seems like a foot and a half didn't degrade the signal. But I am not sure how far you can take it. We got weaker results using a cord about 4 foot long.|